matrixnv

REVIEWFlaviviruses,anexpandingthreatinpublichealth:focusondengue,WestNile,andJapaneseencephalitisvirusCarloAmorinDaep&JorgeL.
Muoz-Jordán&EliseoAlbertoEugeninReceived:11June2014/Revised:1August2014/Accepted:26August2014/Publishedonline:7October2014#JournalofNeuroVirology,Inc.
2014AbstractTheflavivirusesdengue,WestNile,andJapaneseencephalitisrepresentthreemajormosquito-bornevirusesworldwide.
Thesepathogensimpactthelivesofmillionsofindividualsandpotentiallycouldaffectnon-endemicareasalreadycolonizedbymosquitovectors.
Unintentionaltransportofinfectedvectors(AedesandCulexspp.
),travelingwithinendemicareas,rapidadaptationoftheinsectsintonewgeographiclocations,climatechange,andlackofmedicalsurveil-lancehavegreatlycontributedtotheincreaseinflaviviralinfectionsworldwide.
Themechanismsbywhichflavivirusesaltertheimmuneandthecentralnervoussystemhaveonlyrecentlybeenexaminedde-spitethealarmingnumberofinfections,relateddeaths,andincreasingglobaldistribution.
Inthisreview,wewilldiscusstheexpansionofthegeographicareasaf-fectedbyflaviviruses,thepotentialthreatstopreviouslyunaffectedcountries,themechanismsofpathogenesis,andthepotentialtherapeuticinterventionstolimitthedevastatingconsequencesoftheseviruses.
KeywordsVaccines.
Mosquito.
Fever.
Bioterrorism.
BrainIntroductionThegenusFlavivirusiscomposedofapproximately73arthropod-borneviruses,orarboviruses,thatinfectrodents,pigs,birds,non-humanprimates,humans,andothermamma-lianhosts.
Severalmembersofthisvirusfamilywhichincludethedenguevirus(DENV),Japaneseencephalitisvirus(JEV),WestNilevirus(WNV),St.
Louisencephalitisvirus,andyellowfevervirusareassociatedwithimportanthumandis-easeswhicharetransmittedbyarthropodvectors.
HepatitisCvirusisanotableexceptionaswhileitisrelatedtotheothermediallyimportantflaviviruses,itisoneofthefewmembersofthisviralfamilythatisnotvector-borne.
Mostofthesevirusescancauseawidevarietyofclinicalmanifestationsandcomplicationssuchasundifferentiatedfever,capillaryleak-age–hemorrhagicdisease,andencephalitiswhichcanpoten-tiallyleadtodeath.
Mostflavivirusesarezoonoticanddependuponnon-humananimalvectorsfortheirsurvival,replication,anddispersalwiththeexceptionofDENVwhichpropagatesmainlyinhumans.
Whiletheevolutionaryeventthatledtotheincreasedspreadofthevirusesisstillunknown,populationmovements,rapidurbanization,andwidespreaddeforestationhavecontributedtotheexpansionofthepathogensintopre-viouslynon-endemicareas(Bhattetal.
2013;PetersenandMarfin2005).
Inaddition,burgeoningtraveltoendemicareasandtheslowincreaseinglobaltemperaturesduetoclimatechangeshaveallowedtheexpansionofDENV,WNVandJEVintonewterritories(Beattyetal.
2005;Caminadeetal.
2012;Hansen2006;Rahmstorfetal.
2007).
Despitetheadaptation,wildreservoirsofDENVarestillmaintainedinsubtropicalandtropicalareasthatsupportamosquito–monkey–mosquitotransmissioncycle(Gubler2002).
Whilemostflavivirusesareendemicintropicalareas,thedistributionofseveralmembersoftheviralfamilysuchasWNVhasextendedtotemperateareasincludingtheUSAwithinthepastdecade(Caminadeetal.
2012).
C.
A.
Daep:E.
A.
EugeninPublicHealthResearchInstitute(PHRI),Newark,NJ,USAC.
A.
Daep:E.
A.
Eugenin(*)DepartmentofMicrobiologyandMolecularGenetics,RutgersNewJerseyMedicalSchool,RutgerstheStateUniversityofNewJersey,Newark,NJ,USAe-mail:eliseo.
eugenin@rutgers.
eduJ.
L.
Muoz-JordánCentersforDiseaseControlandPreventionDengueBranch,1324CaadaStreet,SanJuan00971,PuertoRicoJ.
Neurovirol.
(2014)20:539–560DOI10.
1007/s13365-014-0285-zFlavivirusepidemiologyandglobaldispersalFlavivirusesareimportanthumanpathogensthathaveplaguedmankind,accountingformillionsofmortalityworld-wide(Table1).
Thefirstrecordedepidemicofdengue-likediseasewasreportedbetween1779and1780whenoutbreaksoccurredinAsia,Africa,andNorthAmerica(Gubler1998,2002).
Sinceitsemergence,fourDENVcloselyrelatedbutgeneticallydistinctserotypeshavebeenidentified(Zanottoetal.
1996).
Eachserotypeisbelievedtohaveemergedfromacommonancestorandevolvedseparately(Kawaguchietal.
2003)despitepossessingdifferentantigenicityandcausingdifferentdegreesofillnessseveritiesincludingdenguehem-orrhagicfever(DHF;currentlybeingchangedtosevereden-gueasindicatedbyWHO).
Variationswithineachserotypehavebeengeneticallydetected,thoughnotlimitedto,withintheenvelopeprotein(E)andnon-structuralprotein,NS5,withintheviralgenome.
WNVisbeingtransmittedwithintheUSpopulationsincethefirstreportedcasein1999(seeTable1fordetails).
Sincethen,thetotalnumberofWestNilevirusinfectioncaseshasbeenincreasingannuallywithintheUSA(http://www.
cdc.
gov/westnile/resources/pdfs/cummulative/99_2013_cummulativeHumanCases.
pdf).
Currently,DENVisendemicinatleast100countriesthroughoutAsia,thePacific,theAmericas,Africa,andtheCaribbean(Fig.
1).
Approximatelyonemillioninfectedindividualssufferfromeitherdenguefeverordenguehemorrhagicfeverannuallywithdengue-relateddeathsesti-matedtooccurbetween1and5%ofthoseinfectedasreportedbyWHO(http://whqlibdoc.
who.
int/publications/2009/9789241547871_eng.
pdf)(seeTable1).
DENVinfectionsareoftenself-limitingandrangefromasymptomat-ictorelativelymild,undifferentiatedillness,withthepatienteventuallymakingfullrecovery.
However,approximately5%ofsymptomaticcasesprogresstoamoreseverediseasewhosemanifestationsincludefever,myalgia,vomiting,andacuteabdominalpain.
Thesymptomsthenprogressfurthertohy-potension,tachycardia,decreasedperipheralperfusion,perisoreositis,andmyocarditis(Krishnamurtietal.
2001;Malavigeetal.
2004).
Inadditiontothesesymptoms,hemor-rhagedevelopsapproximately7dayspost-infectionwithnoobservedcirculatorycollapse(Krishnamurtietal.
2001).
Factorsinfluencingdiseaseseverityarenotwellunderstood.
Apredispositiontosevereillnessinsecondaryinfectionsduetoantibody-dependentenhancementofinfectionisoftencited(Kliksetal.
1989).
IntheUSAanditsterritories,DENVtransmissionprimar-ilyoccursintropicalandsubtropicalareassuchasPuertoRico,theUSVirginIslands,AmericanSamoa,andtheUSA-affiliatedPacificIslands(Imrieetal.
2006;Mohammedetal.
2010a;Rigau-Perezetal.
2001;Tomasheketal.
2009),wheredengueisendemic.
DenguehasbeenfoundtobethemostfrequentcauseoffebrileillnessamongUSTable1Flavivirusepidemiology,infection,andcomplicationsVirusAtriskindividualsAnnuallyreportednewinfectioncasesSymptomsNeurologicdiseaseMortalityrateJapaneseencephalitisvirus(JEV)Children–youngadult(0–15yearsold)35,000–50,000newcases(inJEV-endemiccountries)Pyrexia,cephalalgia,vomiting,neurologicdysfunction,muscleweakness,seizures,lossofmotorfunctionParkinsonismFlaccidparalysisComaAcuteencephalitis~25–30%Dengue(DENV)NoagedistinctionOnemillioncases(globally)Pyrexia,myalgia,vomiting,cephalalgia,abdominalpain,bleeding,lowbloodpressure,tachycardia,seizuresEncephalitis~1–5%WestNilevirus(WNV)Adultsandimmunocompromisedpersons(≥50yearsoldatgreaterriskofdevelopingmoreseverediseaseandcomplications)Rangingfrom20to5,674casesannuallybetween1999and2012intheUSA;reportsofWNVinfectionandmortalityratesreportedinCanadaandMexicoFever,cephalalgia,nausea,vomiting,myalgia,muscleweakness,lowerbackpain,lossofmotorfunctionEncephalitisMeningitis~3–15%DatacollectedfromtheCentersforDiseaseControl(www.
cdc.
gov)andreviewbyMalavigeetal.
,Post-GraduateMedicalJournal80(948):588–601,http://www.
cdc.
gov/westnile/resources/pdfs/cummulative/99_2012_CasesAndDeathsClinicalPresentationHumanCases.
pdf,andhttp://www.
cdc.
gov/westnile/resources/pdfs/cummulative/99_2012_cummulativeHumanCases.
pdf540J.
Neurovirol.
(2014)20:539–560travelersreturningfromAsia,LatinAmerica,andtheCaribbean(Freedmanetal.
2006;Mohammedetal.
2010b;Sharpetal.
2012).
Inaddition,outbreaksofdengueoccursporadicallyinnon-endemicareaswherethemosquitovectorsexist(Brunkardetal.
2007;Grahametal.
2011;Radkeetal.
2012;Ramosetal.
2008),Hawaii(Effleretal.
2005),andFlorida(Radkeetal.
2012).
Meanwhile,WNVinfectionshavebeenreportedthroughoutthecontinentalUSA.
WhiletheriskofWNVinfectionwithinvariousagegroupsremainsthesame,thepotentialfordevelopingneurologiccomplicationsduetoWNVinfectionincreaseswithage.
Inthepast10years,approximately40,000individualshavebecomeinfectedwithWNVintheUSA(http://www.
cdc.
gov/westnile/resources/pdfs/cummulative/99_2013_cummulativeHumanCases.
pdf),ofwhich~20%developedneuroinvasivediseases(i.
e.
,encephalitisandmeningitis)with12%fatalityrate(Lindseyetal.
2010).
Interestingly,~80%ofWNV-infectedindividualsareasymptomatic.
WithindaysfollowinginfectionwithJEV,thehostbeginstoexhibitclinicalmanifestationsofthediseasebeginningwithcephalalgia,vomiting,andpyrexiawhichlastapproximately1week(Sarkarietal.
2012b),afterwhichneurologicdisordersensue,hallmarkedbyParkinsonism,flaccidparalysis,andcoma.
Uptoonethirdofinfectedpatientsacquireacuteenceph-alitis,whichcanoftenleadtocomplicationsandpatientfatality(Leeetal.
2012;Sarkarietal.
2012a,b).
Indeedupto50%ofpatientswhocontractthevirusoftendieduetocomplications.
Interestingly,patientswhoenterconvalescenceremainseropos-itiveagainstJEVdespitepersistentviremia(Ravietal.
1993).
Currently,therearenoreportedJEVcaseswithintheUSA.
DistributionofviralvectorsDENVistransmittedtohumansbythemosquitovectorsAedesaegyptiandAedesalbopictus.
Similarly,theglobaldisseminationofWNV(Fig.
2)andJEV(Fig.
3)reliesontheCulexspeciesofmosquitoesfortheirdispersal,inpartic-ularCulexquinquefasciatus.
UnlikeWNV,JEViscurrentlylocalizedinpartsofAsiaandsurroundingislandsandthenorthernregionofQueensland,Australia.
Thesemosquitoes,inparticularA.
aegypti,havebecomewidelydistributedacrosstropicalandsubtropicalareas,includingvastareasoftheUSA(Figs.
1and2).
ThespreadoftheDENVintheUSAFig.
1GlobaldistributionofDENVinrelationtoitsarthropodvectors.
DENVisendemicinpartsofAsia,Australia,Africa,andLatinAmerica(areabetweenthesolidlines)andslowlyexpandingtootherpartsoftheglobe.
Currently,DENVislocatedwithinthedistributionrangeofA.
aegyptiandA.
albopictus(dottedline).
Thepresenceofthesemosquitovectorsinnon-DENVendemicareassuggeststhepotentialfortheexpansionofthevirusintonewregionsifoptimalconditionsarepresent.
CountrieshighlightedinredrepresentareasthatareendemictoWNVorhavereportedcasesofthevirus.
SimilartoDENV,theexpansionofWNVisduetonumerousreasonswhichincludeincreasedtraveltoWNVendemicareasandtheintroductionofsuitablearthropodwithintheseregionsJ.
Neurovirol.
(2014)20:539–560541isexacerbatedbytheexpandedrangeofA.
albopictusinrecentyears,reachingasfarasNewEngland(Fig.
2)(Moussonetal.
2005).
Inaddition,mosquitospeciescapableoftransmittingWNVhavealsobeendiscoveredtobeasfarnorthasCanada(www.
hc-sc.
gc.
ca).
ThespreadofWNVaswellasDENVisfacilitatedbythedispersalofsuitablearthropodvectorswhichhasbeenacceleratedbyrapidurbanization,increasedtravelintoendemiccountries,andadaptationtoclimatechanges.
Togethertheseeventsareexpectedtocontributetoincreasesinthenumberofindividualsaffectedbythesepathogens(Andersetal.
2011;PetersenandMarfin2005).
Typically,flaviviraltransmissionintohumansoccurswithin2weeksofviremiafollowingtheinitialfeedingfromaninfectedhost.
Afterenteringanavemosquitointhebloodmeal,theviruswillrequireanadditional8–12daysofincubationbeforeitcanbere-transmittedtoanotherhuman.
Onceinfectedwiththevirus,themosquitoremainsinfectiousfortheremainderofitslife.
Symptomsamonginfectedhumanhoststypicallydevelopwithin7daysafterthemosquitobiteandlastsbetween3and14days.
Whilesomeindividualsdonotdevelopanysignificantsymptoms,theycanstillsuccessfullytransmitthesevirusestoothersviamosquitoes.
DENVisuniqueamongotherflavivirusesastheyaretheonlyviruswithinthefamilywhichutilizeshumansasitsamplifyinghost.
AmongWNVandJEV,viralamplificationhasbeendocumentedtooccurwithinvariousmammalianhostsincludinghorses,sheep,pigs,andgoats;inthecaseofJEV,thevirushasalsobeenreportedinbatsasdetectedbyqPCR(Liuetal.
2013;Olaleyeetal.
1990;Pauvolid-Correaetal.
2011;Peirisetal.
1992).
TheexpansionofWNVandJEVacrossdifferentgeographicalregionsisbelievedtobemediatedbytheseasonalmigrationofbirds(Reedetal.
2003).
Dengueisendemictomanypartsofthetropicsandsub-tropics,withoutbreakscloselycorrelatedwiththecompletionoftheannualmonsoonseasonasreportedbytheWHO.
Duringthistime,anincreaseintheAedessp.
mosquitopop-ulationisalsotypicallyobserved.
Furthermore,theriskofcontractingDHFalsoincreasesasmorehumansbecomeFig.
2DistributionofWNVandDENVinfectionshavebeenreportedintheUSA.
Todate,WNVinfections(green)havebeendocumentedthroughouttheUSAwiththeexceptionofAlaska(gray).
Texas,Florida,andNewYorkarecurrentlytheonlystatesinwhichbothWNVandlocallyacquiredDENV(red)havebeenreported.
WhilesomecasesofDFhavebeenreportedinNewYork(yellow),DENVinfectionshavebeenruledoutastravel-associatedcases.
ThedottedlinedesignatesthenorthernmostdistributionoftheWNVmosquitovector,Culexsp.
,whilethedashedlineillustratesthenorthernmostterritoryoftheDENVmos-quitovector,Aedessp.
,intheUSA542J.
Neurovirol.
(2014)20:539–560infectedwiththevirusduringthisshorttimeperiod.
Acom-binationofoptimalenvironmentalconditionsthatfacilitateanincreaseininfectedarthropodvectors,greaterpresenceofindividualswithnoimmunitytooneofthefourvirustypes(DENV-1–4),andanopportunityforinfectedvector–hostcontactarerequiredfortheonsetofDENVandotherflavivi-rusepidemics.
Interestingly,despitetheinductionoflifelongprotectiveimmunityagainstoneDENVserotype,protectionagainstthevirusispartialandtransientagainstotherserotypes(Chenetal.
2004).
SecondaryinfectionbyadifferentDENVserotypeoftenleadstoincreasedseverityandcarriesahigherriskofsusceptibilitytoDHFandpatientmortality.
DHFisalife-threateningillnesscharacterizedbyinternalbleeding,seri-ousbraincompromise,organfailure,andeventuallydeath.
Insomecases,dengueshocksyndromeisobservedamongDFandDHFpatients.
WhileitisgenerallyacceptedthattertiaryandquartenaryDENVinfectionsareasymptomatic,thelackofclinicaldatathataccuratelydeterminemultipleDENVinfec-tionsamongaffectedindividualsandtheimportanceofADEmakethesurveillanceofthevirusanditstreatmentimportant.
Therearecurrentlynoapprovedvaccinesortherapiesforthedisease.
Treatmentofinfectedpatientsismostlypalliative,withanadministrationoffluidsandanoccasionalbloodtrans-fusionintheeventofseverehemorrhage.
ThelackoftreatmentforDENVandrelatedflaviviruses(i.
e.
,WNVandJEV)makesthesediseasesdebilitatinganddeadly.
Inthepast,DHFcasesintheUSAwereonlyobservedamongtravelerswhohavereturnedfromvisitstodengue-endemicareas.
However,datafromtheCentersforDiseaseControl(CDC,http://www.
cdc.
gov/dengue/)andtheNationalResourcesDefenseCouncil(NRDC,http://www.
nrdc.
org/health/dengue/)indicatethatlocalizedcasesofDENVinfectionhavealreadybeendetectedinHawaii,Texas,Florida,andNewYorkalongwiththemosquitoesthatareresponsibleforharboringthevirus(Fig.
2).
WhiletheUSpopulationcurrentlyhasnoimmunitytothevirusduetoinfrequentinteractionsbetweeninfectedindividualsandviralvectorswhicharenecessaryforsuccessfuldisseminationofDENV,thepresenceofDENVwithintheUSAsuggeststheimminentriskofinfectionamongmillionsofAmericans.
Furthermore,therapidspreadoftheWNVthroughouttheUSAsuggeststhepossibilityforDENVtobecomeprevalentwithintheUSgiventheproperexistingconditions.
FlavivirusgeneticsandlifecycleFlavivirusesarecomposedofasingle-strandedpositive-senseRNAgenome(~11kilobases)packagedintoa40–60-nmvirioncomprisingofasphericalnucleocapsidcorecoatedinanicosahedralenvelope(Harrisetal.
2006;Rodenhuis-Zybertetal.
2010).
TheentireflaviviralgenomeconsistsoftengenesJ.
Neurovirol.
(2014)20:539–560543Fig.
3DistributionofJEV.
JEViscurrentlyendemicwithinsouth,east,andsoutheastAsia(highlightedinblue)anditssurroundingislands,indicatedbytheredborder.
Todate,therearenoreportedcasesofJEVoutsideofthisregion;however,theexpansionofitsmosquitovector,Culexsp.
,toothercountriesworldwidemakesspreadingofthisdangerouspathogenasignificantthreatencodingalargepolyproteinthatispost-translationallycleavedbyhostandviralproteasestoproducethreestructural(proteincapsid,C;prM/Mprotein,andenvelopeprotein,E)andsevennon-structuralproteins(NS1,NS2A,NS2B,NS3,NS4A,NS4B,andNS5)(Fig.
4)(Leyssenetal.
2000).
TheNSregionencodesforvariousimportantproteases,inpartic-ularNS3andNS2B,whichareimportantintheauto-processingofthevirus,mediationofviralgenomereplication,andviruspackaging(ClydeandHarris2006).
Thetranscrip-tionofthesegenesiscontrolledbythe5′-and3′-untranslatedregions(UTR)flankingtheviralgenome(AppaiahgariandVrati2012b;Leyssenetal.
2000;Lindenbachetal.
2007).
Themechanismsofflaviviralinfectionofthehostcellanditslifecyclearenotfullyunderstood.
Thecurrentconsensusisthatendocytosisoftheviralparticleisimportantinthesuc-cessfulinfectionofthecellandtheproductionofprogenyviruses(Fig.
5).
AttachmentoftheDENVandotherflavivirusestocellsutilizesmultiplepotentialreceptorsthatfacilitatetheattachmentandinternalizationofthevirus(i.
e.
,CD14,R80,heparinsulfate,C-typelectinreceptors,DC-SIGN,andmannosereceptors)(Rodenhuis-Zybertetal.
2010);however,theexactmechanismbywhichDENVandotherflavivirusesusethesemoleculesforcellularinternaliza-tionisstillunderinvestigation.
Theattachedvirusisinternal-izedintoanendosomalcompartmentwhichacidifiestofacil-itatethefusionoftheviralenvelopewiththeendosomalcompartment(Fig.
5).
Thisfusionoftheviralenvelopeisduetotherearrangementofthecapsidproteins,resultinginthereleaseofthevirusintothehostcell(vanderSchaaretal.
2008).
TheviralRNAisreleasedintothehostcytoplasmandtransportedtotheendoplasmicreticulum(ER)whereitun-dergoestwodifferentfates:first,thepositivesenseRNAistranslatedtoproduceapolyproteinthatispost-translationallycleavedintostructuralandnon-structuralproteins(listedear-lier)or,second,thegeneticmaterialisconvertedintoaneg-ativesenseRNAbyviralNS5RNA-dependentRNApoly-merases(RdRp)andusedtoproducepositive-strandedRNAcopies(Fig.
5).
TheviralgenomeisthenpackagedwithinthecytoplasmbytheactionofproteinCtoformthenucleocapsid,whiletheprMandEproteinsheterodimerizewithinthelumenoftheERandinitiateviralbudding(Kuhnetal.
2002;Zhangetal.
2004).
NascentvirionparticlesformedwithintheERtravelthroughthesecretorypathwayandintotheGolgiappa-ratus.
ChangesinpHwithinthetrans-GolginetworktriggerthedissociationoftheprM/Eheterodimersactivatingthecellularendo-proteasefurin.
ActivationofthisproteaseleadstocleavageoftheprMproteintogenerateproteinM(mem-braneassociated)andthepeptidepr(Rauscheretal.
1997;Yuetal.
2008;Zybertetal.
2008).
Thecleavageofthisproteincomplexresultsinamature,fullyinfectiousvirion.
ImmunopathogenesisandcentralnervoussystempathogenesisStudiesofDENVimmunopathogenesisarehighlylimitedduetothenatureofthediseaseandlackofanimalmodelsthatrecapitulatethedisease.
However,resultsobtainedfromhu-manizedmiceshowsomesimilaritiesinthedevelopmentandprogressionofthediseasewhichistypicallyobservedinhumans.
Thus,thesemodelswillplayanimportantroleinelucidatingflaviviralpathogenesisnowandinthefuture(MotaandRico-Hesse2011).
Epidemiologicalstudieshaveidentifiedsomeoftheriskfactorsimportantfordiseasedevel-opmentandseverityfollowingflaviviralinfection.
Thesefactorsincludeage(youngerpeoplearemostsusceptibletoDENVandJEVinfection,whileolderorimmunocompromisedindividualsareaffectedbyWNV),highbodymassindex,viralstrain,gender,geneticvariationofthemajorhistocompatibilitycom-plex(MHC)-classI-relatedsequenceB,dendriticcell-specificintercellularadhesionmolecule-3-grabbingnon-integrin(DC-SIGN),tumornecrosisfactor-α(TNF-α)andphospholi-paseCepsilon1genes,environmentalconditionssuchasmos-quitospreadandtemperature,andsecondaryinfectionwithadifferentviralstrain(inthecaseofdengue)(Andersetal.
2011;Khoretal.
2011;Nguyenetal.
2005;Simmonsetal.
2012).
InDENVinfection,theserotype-specificlifeimmunityacquiredfollowingtheinitialinfectionbythevirusdoesnotprovidecompleteprotectiontootherinfectingserotypes.
Infact,subsequentDENVinfectionsincreasethedevelopmentFig.
4Flavivirusgenome.
Theflavivirusgenomeconsistsofasingle-strandedpositive-senseRNAencodingapolyproteinpost-translationallycleavedbyhostproteases(sitesdesignatedbythebluearrows)andviralproteases(sitesdesignatedbygreenarrows).
Thesitedesignatedbytheredarrowiscleavedbyayettobeidentifiedprotease.
Processingofthepolyproteinproducesthreestructural(whiteboxes)andsevennon-structuralgenes(grayboxes).
TheprMproteinisthenlatercleavedwithintheGolgitoreleasetheMproteinimportantforthematurationofthevirus.
TranslationofviralRNAiscontrolledbytheuntranslatedregions(UTR)locatedatthe5′-and3′-endsoftheRNA544J.
Neurovirol.
(2014)20:539–560ofmoreseveredengueillnessessuchDHF(Halsteadetal.
2002;Kliksetal.
1988).
TheincreaseddiseaseseverityduringsecondaryDENVinfectionsispotentiallyduetotheroleofmemorycellsandantibodies.
Thisistheconceptforantibody-dependentenhancement(ADE)ofsecondarydengueinfec-tions(HalsteadandO'Rourke1977).
DuringADE,antibodiesgeneratedaftertheinitialinfectionrecognizedifferentDENVserotypesduringsecondaryinfectionsandfacilitateincreasedbindingandinternalizationofthevirusviatheFcreceptorsonleukocytesandblood–brainbarrier(BBB)cells.
Theadher-enceandinfectionoftheBBBbyDENVleadstoinflamma-torycytokineandchemokineproduction(i.
e.
,TNF-α,MCP-1/CCL2,IL-2,IL-6,IL-8,IL-10,andIL-12)aswellasotherinflammatoryfactorsthatleadtoBBBcompromiseandCNSdysfunction(Andersonetal.
2011;Chaturvedietal.
2000;Chen2012;Gubler1998;Malavigeetal.
2004;Priyadarshinietal.
2010;Restrepoetal.
2008a,b).
ThisprovidespotentialtargetsfortherapeuticinterventionagainstsucceedingDENVinfections.
Amongleukocytepopulations,dendriticandnaturalkiller(NK)cellsarethefirstonestobecomeinfected.
Theinfectionofthesecellsoccursthroughpathogen-recognizingreceptors,suchastoll-likereceptorsandDC-SIGN,andelicitsinflamma-torysignalsthatleadtoaTh2immuneresponseandeventualvascularbarrierdysfunction(Chaturvedietal.
2000).
Monocyte/macrophagesandlymphoidcells(TandBcells)havealsobeendescribedasmajorpreferentialtargetsforflavivirusesduetothepresenceofviralRNAorproteinsininfectedcellswhichhavebeencollectedfromlymphoidtissues(Durbinetal.
2008;Jessieetal.
2004;Kingetal.
1999;Linetal.
2002;MentorandKurane1997;Srikiatkhachornetal.
2012).
Thehighviraltiterswithinthegerminalcentersofthesetissuesalsosuggestthatthesesitescanharborviralparticlesthatcandisseminateandinfectothersiteswithinthehost.
Interestingly,flaviviruseshavedevelopedstrategiestocircumventthehostimmuneresponselimitingclearanceeitherbyinhibitingIFNsecretion(Munoz-Jordanetal.
2003;Umareddyetal.
2008)orbyreducingantigenpresentationthroughthelimitationofMHCandco-stimulatorymoleculeexpression(Palmeretal.
2005).
ThelossofthesemoleculeswillleadtoanimpairmentofCD4+TlymphocyteactivationandCD8+Tlymphocyteresponseandthusleadingtothelossofanimmuneresponseagainstthevirusesanddiseasedevelopment(Aleyasetal.
2009,2010;Chaseetal.
2011).
TheinvivocellulartargetsofDENVandotherflavivirusesintheCNSremaintobefullycharacterized;however,ourlaboratoryandothershaveobservedthatprimaryhumanastro-cytesandbrainmicrovascularendothelialcellscanbeinfectedbyDENV(Daep,Munoz-JordanandEugenin,unpublishedFig.
5Flaviviruslifecycle.
Followingattachmenttothehostextracel-lularsurface(1),thevirusisendocytosed(2)andencapsulatedinsideanendosomalvacuole.
AcidificationoftheendosomalcompartmentalterstheEprotein,causingthefusionoftheviruswiththeendosome(3),facilitatingvirionreleaseintotheintracellularcompartmentwhereitisunpackaged(4).
Thereleasedviralgenomeundergoestwodifferentfates:theviralgenomeiseithertransportedtotheendoplasmicreticulumwhereitistranslatedintoapolyprotein(5a)orconvertedintoanegative-senseRNAtomakepositive-senseRNAcopies(5b).
Thelargepolyproteinispost-translationallyprocessed(6),producingstructuralandnon-structuralcomponentsimportantforvirusassemblyandmaturation.
TheviralgenomeispackagedintoacapsidandtransportedtotheGolgiwhereitiscoatedbytheE/Mproteincomplex(7)toproduceamaturevirion(8)J.
Neurovirol.
(2014)20:539–560545data).
GiventhepotentialimportanceofastrocytesasHIVreservoirswithinthecentralnervoussystem(CNS)(EugeninandBerman2007;Eugeninetal.
2011),thesecellsmayalsofunctiontomaintainDENVreservoirswithinthebrain.
Todate,thefullmechanismofflavivirusinfectionoftheCNSremainspoorlyunderstoodduetoearlystudieswhichdidnotdetectpathologicalsignsofviralinvasionwithintheCNS(Burke1968;NathansonandCole1970).
DeeperexaminationofCNSpathologyfollowingDENVinfection,however,willpro-videgroundbreakinginformationthatwillelucidatetheroleoftheblood–brainbarrier,leukocytes,andCNSinflammationfollowingflaviviralinfectioninthedevelopmentofdenguefever(DF)andDHF.
OldermanuscriptsindicatethatDENVantigenscanbefoundinseveraltissuesincludingneuronsinthecerebrum,Purkinje'sandgranularcellsinthecerebellum,astrocyte,mi-croglia,andcellsofthechoroidplexus(Bhoopatetal.
1996a).
However,earlierreportsdescribingDHFpathologyindicatesnobraincompromiseandclearlystatedthatminimaldamagewasobserved(Burke1968;NathansonandCole1970)despitethedevastationoftheCNSfollowinginfectionbyDENVandotherflaviviruses.
Inaddition,positivedetectionofflaviviralantigenswithoutviralRNA(Jessieetal.
2004)indicatedviraluptakebyendocytosisand/orphagocytosisandnotbyproduc-tiveinfectionthatresultinprogenyvirions.
Recentimprove-mentsinresearchtechniquescouldprovidedetectionassayswithincreasedsensitivityandimprovedaccuracy.
Inagree-ment,recentpublicationshavedemonstratedthepresenceofdengueantigensintheCNSduetothedetectionofviralproteins,immunoglobulin,andRNA(Araujoetal.
2011;Limaetal.
2011;Miagostovichetal.
1997a,b).
ViralinfiltrationandsubsequentinfectionoftheCNShavebeenlinkeddirectlytoCNSviralreplication.
Thus,themechanismofinvasionoftheCNSrequiresreexaminationandfurtherstudies.
Laterinthisreview,wewilldiscussallthesemechanisms.
RoleofleukocytesinCNSdiseaseAlthoughthereisageneralconsensusthatflavivirusescaninfectmononuclearcellsinvivo,onlyfewcelltypeshavebeenidentifiedtobetargetedforinfectioninvitro.
IndeedautopsystudiesclearlyindicatedthatpresenceofflaviviruseswithintheLangerhan'scellslocatedintheskin(Clydeetal.
2006).
However,theparticipationoftheseorothercelltypesinflaviviralpathogenesishasyettobefullyexplored.
Subsequently,wewilldiscusstheevidenceofleukocytein-fectionsbyflaviviruses.
DendriticcellsFollowingabitefromaninfectedmosquito,flavivirusesin-cludingDENV,WNV,andJEVareinoculatedintothehumanbodyandimmediatelyinteractwithresidentdendriticcells(DC)foundintheepidermisanddermislayersoftheskin.
ThesecellsoriginatefromthebonemarrowasCD34+pro-genitorsandlaterdifferentiateintolymphoid/plasmacytoid(pDC;IL-3-andCD40ligand-dependentmaturation)ormy-eloidlineage(mDC;GM-CSF-dependentmaturation).
FollowingentryofDENVintoDC,ithasbeenobservedthatthetotalnumberofcirculatingDCsdecreasesandunrespon-sivetherebyalteringthehostimmuneresponse.
Furthermore,invitroexperimentsutilizingmaturePBMC-derivedDCsshowedanalteredprofileofinflammatoryproduction(Hoberetal.
1996a,b).
However,infiltrationofinfectedDCsintothelymphnodesactivatesCD4+andCD8+Tlym-phocytesandelicitsanadaptiveimmuneresponseagainstthevirus.
Thus,flavivirusesuseDCsasgatewaycellstoinfiltrateandsuccessfullyinfecttheirhumanhost.
Monocyte/macrophagesMonocytesareoneofthenaturalhostsofDENV(Durbinetal.
2008)andareimplicatedinthepathogenesisofDFandDHF(Halstead1988;Kliksetal.
1989).
Interestingly,depletionofmonocytesfrommurinemodelsresultedinatenfoldincreaseinviralload,suggestingthatmonocytesarealsoimportantincontrollingviralinfection(Finketal.
2009).
DENVinfectionalsoacceleratesthedifferentiationofmonocytesintomacro-phageandfacilitatescellulartransmigrationintotheCNSwhereinflammatorycytokines,chemokines,viralproteins,andotherinflammatoryfactorsareproduced.
InflammationwithintheCNSleadstocompromiseandlossofendothelialfunctionandpotentiallyBBBdysfunction.
IndeedDENV-infectedCD16+monocytesproduceIL-1β,TNFα,CCL2,CCL3,andCCL4(Azeredoetal.
2010).
ThesecytokinesandchemokineshavebeenshowntobetightlyinvolvedinthelossofBBBintegrityandthedevelopmentofCNSdiseaseinthecontextofHIVCNSinfection(Robertsetal.
2012a).
Theseobservationsarealsoconsistentwithotherviraldis-easesthatcompromisetheCNS;forinstance,ithasbeenreportedthatHIV-infectedpatientshaveanelevatedCD14+CD16+monocytepopulationwhichcantransmigrateintotheCNSinresponsetoCCL2andproduceinflammatoryfactorsthatdisrupttheBBB(Eugeninetal.
2006b;Williamsetal.
2012).
However,todate,thereareveryfewstudiesdescribingtheneuropathogenesisofflavivirusesinthiscelllinage.
LymphocytesTheroleoflymphocytesindiseasedevelopmentfollowingflaviviralinfectionhasnotyetbeenfullycharacterizedduetovariousobservedconundrumswithinthediseasepathogenesis.
InvitrostudieshaveshownthatDENVcaninfectaswellasactivatebothCD4+andCD8+Tcells(MentorandKurane1997;546J.
Neurovirol.
(2014)20:539–560Pangetal.
2007).
IndeedDENV-specificCD4+andCD8+TcellshavebeenidentifiedamongpatientswithDF(Gagnonetal.
1996),withthelatterlymphocytepopulationimportantforcontrollingviralspreadandreplicationwithinthehost.
However,studieshaveshownthatCD8+cytotoxiclymphocytesalsocontributetoDFpathogenesisandthusnegativelyimpactingthehealthoftheinfectedindividual.
ThearrivalofCD8+Tcellsattheinfectionsitesinitiatesthedestructionofinfectedcells,facilitatingfurtherproductionofinflammatoryfactorsthatleadtoCNSdamageandvascularendothelialdys-function,resultinginBBBpermeability(Mongkolsapayaetal.
2003;Rothman2009;ScreatonandMongkolsapaya2006).
Byinducingtheproductionofinflammatorycytokines,chemokines,andotherimmunefactors(e.
g.
,IFN-γTNF-α,IL-1β,IL-2,IL-4,Il-6,IL-7,IL-8,IL-18,CCL2,interferons,andseveralsolubleproteinssuchasCD4,sTNFR,andCD8)duringprimaryandsecondaryinfections,theseverityofthediseaseescalatesandleadstothevascularpermeabilityob-servedduringDHF(Azeredoetal.
2010;Davisetal.
2008a;Hoberetal.
1993;Kuraneetal.
1991a,b).
ThissupportstheideathatTcell-producedinflammatorymoleculesarekeyfactorsthatfacilitatediseasedevelopmentfollowingflavivirusinfection,withsomepromotingvascularpermeability.
ThisresultsincompromisedBBBintegrityandCNSdysfunction.
Interestingly,despiteJEV,WNV,andDENVbelongingintheflaviviralfamilyandcausingsimilaroutcomes,thevirusesdifferintheireffectsonthehostimmunesystem.
IndeedithaspreviouslybeenshownthatIFN-γactivityisinhibitedbyDENVbytargetingSTAT2degradation,whereasJEVandWNVdothisbyinhibitingSTAT1(Ashouretal.
2009;Laurent-Rolleetal.
2010;Linetal.
2006;Mazzonetal.
2009).
BlymphocytesinfectedbyDENVhavebeendetectedinboththespleenandbonemarrow(Durbinetal.
2008;Kingetal.
1999;Linetal.
2002),withactiveviralreplicationverifiedbyPCRandWesternblotanalyses(Linetal.
2002).
SimilartoTlymphocytes,theexposureofBcellstoDENVinvitroinducedtheproductionofinflammatorycytokineandDENV-specificimmunoglobulins,bothofwhichhavebeenshowntobeimportantinDENVpathogenesisandDFdevel-opment.
Sinceantibodyproductionisessentialinamplifyinginfectionandinflammation,thissuggeststhatthedysregula-tionofBcellsiscriticalbecausetheynormallyproduceimmunityagainsttheserotype-specificEproteinantigen(Mathewetal.
2011).
Duringsecondaryinfection,Blympho-cyteresponseispredominatelycross-reactivetoothersero-types,withtheproducedheterologousantibodieshavinggreateravidityforthevirusthanhomologousantibodies.
ThisincreasedavidityforthepathogenisimportantduringADEofviralinfectionasobservedinDENVpathogenesis(Linetal.
2002).
DuringADEofvirusinfection,DENVutilizesmemoryantibodiesgeneratedfrompreviousDENVinfectiontobindtoFcreceptorslocatedontheextracellularsurface,facilitatingtheirentryintothehostcell.
Interestingly,vaccinationagainstanyDENVserotypesresultsinfullcytotoxicactivity,cellproliferation,andcontrolledsecretionofregulatorycytokines(Dharakuletal.
1994;Kuraneetal.
1989;Malavigeetal.
2004).
Whilevaccinationwiththerightserotypecanevokeaneffectiveimmuneresponse,someBcellsproduceauto-antibodiesthatundermineimmunityandcontributetoDENVpathogenesis(Malavigeetal.
2004).
Thus,BcellsaretargetedforDENVinfectionandcontributetodiseasedevelopment.
SimilartoDENV,JEVinfectionelevatesthelevelsofinflammatorymoleculesandchemokines(e.
g.
,IFN-α,IFN-γ,IL-6,IL-8,IL-10,CXCL19,CXCL10,CXCL11,TNF-α,MIF,VEGF,sCD4,sCD8,TNFR,sIL-2,IL-1RA,andTGF-β)withinthehost.
Inaddition,thesecretionofmatrixmetalloproteinase-9(MMP-9)atsitesofinfection(Tungetal.
2010),especiallywithintheCNS,hasbeenshowntobeimportantinfacilitatingthebreakdownoftheendothe-lium,leadingtoplasmaleakageandBBBdestruction.
Similarly,theactivationoflymphocytesandincreasednumberofCD14+cellsfollowingJEVinfectionhasbeencorrelatedwiththeseverityofthedisease(PaesslerandWalker2013;Rothman2009).
Identifyingmechanismsbehindthesechang-esisessentialintargetinganddesigningtherapeuticinterven-tionsthatlimitthedevastatingconsequencesofflavivirusinfection.
Blood–brainbarrierdysfunctionandCNScompromiseTheblood–brainbarrierisaphysicalandhighlyspecializedbarrierseparatingtheperipheralcirculationfromtheCNS.
Thisbarrieriscomposedofmultiplecelltypes,includingbrainmicrovascularendothelialcells(BMVEC),astrocyticendfeet,pericytes,andperivascularmacrophages,allofwhichareinclosecontacttoneurons,glialcells,andmicroglia(SpindlerandHsu2012b).
Duetothehighexpressionoftightjunctionproteins,theBBBisnormallyimpermeabletomostperipheralmoleculesandcellsandrestrictsthediffusionofionsandsmallmolecules.
SeveralvirusesaltertheBBBintegrityandfunction,in-cludingHIV-1,humanTlymphotropicviruse1(HTLV-1),lymphocyticchoriomeningitis(LCMV),WNV,andsimianimmunodeficiencyvirus(SIV).
ThemechanismofBBBcom-promiseinvolvestransmigrationofleukocytesandthesevi-rusesintotheCNSparenchyma,leadingtoBBBdisruption,inflammation,andleukocytetransmigrationintotheCNS(Buckneretal.
2006;EugeninandBerman2003;Eugeninetal.
2006b;SpindlerandHsu2012a;Williamsetal.
2012).
HIVtransmigrationandBBBdisruptionarethebestexaminedcasesofCNSviralinvasion.
OurlaboratoryandothershavedemonstratedthatHIVinfectionaltersBBBfunctionbythreedifferentmechanisms:(1)alterationofthemigratorypropertiesJ.
Neurovirol.
(2014)20:539–560547ofleukocytes,(2)changesinBBBpermeability,and(3)secre-tionoffactorsthatcompromiseleukocytemigrationandBBBintegrity.
WeandothershavealsoshownthatHIVinfectionofleukocytesalterstheexpressionofseveraladhesionmoleculesinvolvedinleukocytetransmigrationandincreasesthelevelsofimportantchemokinereceptorssuchasCCR2,whichin-creasesthesensitivitytoCCL2,akeychemokineinvolvedinthepathogenesisofHIVCNSdisease(Eugeninetal.
2006b;Robertsetal.
2012b).
Inaddition,wedemonstratedthatBBBpermeabilityamongneuroAIDSpatientsiscompromisedattwostages:first,duringproductiveHIVinfectionofleukocytesand,second,followingincreasedexpressionofCCL2intheCNS.
ThiscombinationresultsinBBBdisruptionpotentiallyduetoenhancedsecretionofMMPsandotherfactorsthathighlycompromisetheexpressionandfunctionofkeybarriertightjunctionproteinssuchasoccludin,claudin-1,andZO-1(Robertsetal.
2012a,b).
SomefactorsinvolvedinHIVneuropathogenesisincludecleavedformsofadhesionmole-cules,suchasPrPcandPECAM-1,withthelattercompetingwiththePECAM-1–PECAM-1orPrPC–PrPCinteractionsbe-tweenendothelialcells.
Thisdirectcompetitionleadstodesta-bilizationoftheendothelium,compromisingBBBintegrity,therebyfacilitatingleukocytemigrationintotheCNS(Eugeninetal.
2006a;Robertsetal.
2012a).
However,ourexperimentsusingprimaryBMVECsindicatethatCCL2bindingtoitscorrespondingreceptoralonehasprofoundeffectsontightjunctionproteinexpressionandlocalization,resultinginBBBcompromisebyalteringβ-catenindistributionandinter-actionwithadherencejunctionsandPECAM-1(Robertsetal.
2012a,b).
Thus,HIVCNSinvasionisahighlyregulatedprocessandinvolvesseveralhostandviralcomponents,butwhetherthesemechanismsaresimilarinflavivirusesistotallyunknown.
AmongthebestdescribedcasesofCNSinfectioninvolvesWNV.
DuetothecloserelationofWNVwithDENVandJEV,weexpectedthemechanismofneuropathogenesisofthesevirusestobesimilar(Fig.
6).
WNVattacksthebrain,causingneurotropiceffectsthatincludeencephalitisandfever.
Inmousemodels,WNV-associatedneurologicdiseaseischarac-terizedbyBBBdisruption,increasedleukocyteinfiltration,inflammation,andneuronalloss(Glassetal.
2005;SamuelandDiamond2006).
Someoftheseeffectshavebeenassoci-atedwiththelossofBBBfunctionduetodegradationofjunctionalproteinssuchasZO-1,claudin-1,occludin,JAM-A,β-catenin,VE-cadherinbysecretedmetalloproteinases(MMP)including-1,-3,and-9(Roeetal.
2012a,b).
Inaddition,WNVinfectshumanBMVECs,whichcouldleadtoacompromisedBBBbyinflammatorymechanismsde-scribedpreviously(Vermaetal.
2009).
ExperimentsusingWNV-infectedendothelialcellsindicateanup-regulationofMHC–IandII,ICAM-1,VCAM-1,andE-andP-selectin(Kingetal.
2003),whichcancontributetoleukocyteadhesiontotheBBBandleukocyteinfiltrationintotheCNS.
DuringWNVinfection,CD19+B220-BST-2+leukocyteshavebeendescribedasamajorleukocytepopulationthattransmigratesintotheCNSandcontributestothedevelopmentofenceph-alitis(Brehinetal.
2008).
However,themechanismsbywhichthesecellstransmigrateintotheCNSremainunknown.
FlavivirusinfectionoftheCNS,especiallywithDENV,hasbeenreportedbyafewstudies,withcontradictoryresults.
ViralRNAhasbeendetectedinthecerebrospinalfluidob-tainedfromencephaliticindividuals(Kumaretal.
2008;Fig.
6InfectionofCNSbyflaviviruses.
1InfectionoftheCNSoccurseitherthroughtheadherenceofthevirustomoleculespresentonthesurfaceofbrainmicrovascularendothelialcellsorinfiltrationofinfectedmonocytesacrosstheBBB.
ViralinfiltrationthenleadstoinfectionoftheBBBandCNScellpopulations.
2Infectionofhumanastrocytesleadstochemokineproduction,facilitatingfurtherrecruitmentofmonocytesandmacrophages.
3Neuronsinfectedbyflavivirusesundergoapoptosisandactivatestheresidentmicrogliapopulationwhichproducesaninflammatoryresponse.
Productionofinflammatorycytokines(e.
g.
,TNF-α,IL1β,INF-γ,andIL-4),chemokines(e.
g.
,CCL2,CCL5,CXCL9,CXCL10),inflammatoryenzymes(COX2),andmatrix-metalloproteinases(MMPs)leadstodegradationoftheendothelialbarrierandreleaseofinflammatoryfactors(5)recruitingCD4+andCD8+TlymphocytesintotheCNSparen-chyma.
InfiltrationofCD4+/CD8+Tlymphocytesleadstofurtherinflam-mationandeventuallyCNSdamage548J.
Neurovirol.
(2014)20:539–560Miagostovichetal.
1997b).
Inaddition,DENVantigenshavebeendetectedinneurons,astrocytes,andmicroglia(Bhoopatetal.
1996b;Ramosetal.
1998).
Whileinsituhybridizationforviralparticlesinneurons,BMVECs,andglialcellswerenegative(Jessieetal.
2004),perivascularmacrophageswerepositiveforflaviviralNS3protein.
FurtherstudiesoftheseandotherCNScellsarerequiredtoclarifytheirroleintheneuropathogenesisofDENVandotherflaviviruses.
Thus,itisunclearwhetherproteinsorRNAisaproductofreplication,viraluptake,orboth.
MechanismsofneuronalcompromiseForalongtime,theneurologicinvolvementofflavivirusinfec-tionwasnotconsideredandwasonlyassociatedwithperipheralinfection,suchaslossandextravasationoffluid,hyponatremia,andsystemicfailure.
However,somereportsindicatingtheunequivocalpresenceofviralproteinsandgeneticviralmaterialinthebrainandCSFofinfectedindividualssuggestotherwise(Araujoetal.
2012;Soaresetal.
2006;Solomonetal.
2000).
Thus,thenatureandmechanismsofCNSinjuryinducedbythesevirusesmustbeexamined.
Severalmembersoftheflavi-virusfamilyalsoinducedneuronalapoptosisinassociationwithpost-mitoticneuronalapoptosisthatcannotberegeneratedbyneuronalstemcells(Ogataetal.
1991;Pekoszetal.
1996).
ExperimentsincelllinesindicatethatDENVcandirectlyinfectneurons(Despresetal.
1998),resultinginpermanentdamage.
Despitetheproblemswithanimalmodelsforflavivirusinfections,DENVhasbeeneasilyadaptedtoinvadetheCNSofrodents.
Normally,newbornmiceareinsensitivetonon-neuroadaptedmouseDENVstrains.
Bypassagingtheviruswithinamurinehost,thevirusisneuroadaptedtothemurinehostwithhighlyneurovirulentstrainsofthevirusselectedandamplified(Despresetal.
1998;Sabin1952).
Thisselectionprocessproducesvirusesthatarecapableofinducingneuronalapoptosisininfectedmice,especiallyinthehippocampusandcerebralcortexwhereviralCNSreplicationhasbeenobserved(Despresetal.
1998).
Inaddition,severalDENVinfectionanimalmodelsdisplayinterestingeffectsonneuroinflammationcharacterizedbyup-regulationofimportantchemokines(e.
g.
,CCL2,CCL5,CXCL1,andCXCL2)andinflammatorycyto-kines(e.
g.
,TNF-αandIFN-γ)thatfacilitateleukocyteinfiltra-tionintotheCNS(Amaraletal.
2011a,b).
MiceinfectedintracerebrallywithDENV-3showprogres-sivemeningo-encephalitischaracterizedbyCNSinfiltrationofneutrophilsandmononuclearcellsbyamechanismthatcorre-lateswithachemokine-dependentmechanismthatincludesCCL2andCXCL12(Amaraletal.
2011a,b).
TheseresultsshowtheimportanceofthesecelltypesinthedevelopmentofCNSdiseaseduringDENVinfection.
Interestingly,similarmechanismsofCNSdamagehavebeenobservedinmousemodelsofhepatitisvirus(JHMV),whichresultedinanimalmortality(Zhouetal.
2003).
NeutrophilshaveabiphasicroleduringWNVinfection:first,servingasareservoirforviralreplicationand,second,aidinginviralclearance(Baietal.
2007).
However,theseconflictingrolesofneutrophilsduringWNVpathogenesishavenotbeenexaminedfurther.
IthasbeenobservedthatWNVcauseslimbicseizuresbyamechanisminvolvingN-methyl-D-asparticacidreceptoracti-vation.
Blockingthisreceptoractivationcouldthereforeabro-gatelimbicseizuresandprolonganimalsurvival(Gettsetal.
2007).
InadditiontotheneuronaldamageinducedbyWNVinfection,infiltrationofleukocytes(e.
g.
,neutrophilsandmononuclearcells)wasdetectedintheCNSparenchyma,similartowhatwasseenduringDENV-3infectionoftheCNS.
WNV-mediatedrecruitmentofmicroglialprecursors(i.
e.
,Ly6c+inflammatorymonocytes)indicatesthattheviruscanpassthroughtheBBBbyinfectedleukocytetransmigra-tionintotheCNSandinducelocalinflammation(Gettsetal.
2008).
OnceintheCNS,theviruscaninfectandreplicatewithinneuronsandastrocytes,butnotmicroglia(Cheeranetal.
2005;Dinizetal.
2006;Hussmannetal.
2013)despitedataillustratingmicroglialactivationandsecretionofcyto-kinesandchemokinesthatleadtoCNSdysfunction.
Meanwhile,infectionofCNScellswithJEV,especiallyneurons,resultsinmassiveCNScompromise,encephalitis,anddeath(Chenetal.
2004;Germanetal.
2006;Ghoshaletal.
2007).
ApoptosisinducedbyJEVhasbeenlinkedtothreerelatedmechanisms:(1)directinfectionofneuronsbythevirus,(2)infectionofotherCNScellssuchasmicrogliaandastrocytes,and(3)generalinflammation(Chenetal.
2004;DasandBasu2008;Dasetal.
2008;Raungetal.
2005,2007;Swarupetal.
2008).
Ithasbeenshownthatinflammatorycellsplayanimportantroleintheonset,progression,andseverityofJEV-mediatedencephalitis(Khannaetal.
1991;Mathuretal.
1988;Singhetal.
2000).
Furthermore,reportsindicatethatthelevelsofinflammationcanbeapredictorofpatientoutcomefollowinginfection(Ravietal.
1997).
However,comparedtootherflaviviruses,theextentofglialinfectionduringJEVisunclear.
ItisknownthatJEVtriggersneuronalapoptosisbyinducingendoplasmicreticulum(ER)stressthroughp38mitogen-activatedproteinkinase(MAPK)-dependentanddeath-relatedtranscriptionfactorCHOP(C/EBPhomologousprotein)-mediatedpathways(Suetal.
2002).
Thisisinagree-mentwithWNVwhichalsousesCHOPandmitochondrialpathwaystoinduceapoptosis(ChuandNg2003;Medigeshietal.
2007).
Additionally,phosphatidylinositol3-kinase(PI3K),AKT,superoxide,arachidonicacid,caspases,andal-terationsinbcl-2/Baxalsoparticipateinapoptosis(Courageotetal.
2003;Janetal.
2000;Leeetal.
2005;Linetal.
1997;Parquetetal.
2001).
OurworkinHIV,aclearneurotropicvirus,indicatesthatdespitethelownumbersofHIV-infectedastro-cyteswhichsupportminimaltoundetectedreplication,thebystandermechanismofcelldeathamplificationcanbeusedbythevirustoinduceapoptosisandinflammationusingelec-tricalandchemicalsynapses(EugeninandBerman2007;J.
Neurovirol.
(2014)20:539–560549Eugeninetal.
2011).
Therefore,thenumberofvirus-infectedcellsorthelevelsofviralreplicationarenotgoodindicatorsofcellulardamage.
CytochromeCisamitochondrialproteinthathasbeenshowntoplayanimportantroleincellularrespiration.
Inaddition,cytochromeCparticipatesincellularapoptosisfol-lowingcelldamageorinfection.
DENVinfectiontriggersneuronalapoptosisbyactivationofphospholipaseA2(PLA2),superoxideaniongeneration,cytochromeCreleasefromthemitochondria,caspase-3activation,andNF-kBtranslocation(Janetal.
2000).
ThisissimilartoourresultswhichshowthatHIVinfectionofglialcellsdysregulatescytochromeC.
Despitethehighamountsofcytotoxicintra-cellularcytochromeC,HIV-infectedcellsareprotectedfromapoptosis(EugeninandBerman2013).
Thus,futurestudiesarerequiredtoidentifytheroleofthesefactorsinapoptosis,thegenerationofviralreservoirs,andthedetectionofflaviviruses.
TherapeuticapproachestoflaviviralinfectionsCurrentmanagementofflavivirusinfectionsTherearenoeffectiveantiviraltreatmentsorvaccinesagainstDENVandWNVwithonlyonevaccineavailableagainstJEV.
Thus,infectedpatientscanonlyprovidewithpalliativecarefollowingdiagnosis.
DHFpatientsexhibitinghemor-rhageasdeterminedbyloweredhematocritlevelsareprovid-edbloodtransfusionstoimproveclinicaloutcome.
Furthermore,therearenotreatmentsavailablethatprevent,abolish,orreversethedevastatingCNSconsequencesofflavivirusinfection.
Thus,elucidatingthemechanismsutilizedbyflavivirusestocompromisetheCNSwillleadtobetterdesignofsuccessfultherapeuticsagainstthesepathogens.
Todate,viruscontrolhaslargelyinvolvedeithertheadministra-tionofprophylacticmeasures(e.
g.
,vaccines)orthecontrolofflaviviralarthropodvectors,namely,theCulexandAedesmosquitospecies.
Indeedgiventherapidglobalspreadofthesearthropods,thelatteristheprimaryapproachindicatedbytheCDCandWHOtocontainthespreadofDENV,WNV,andJEV.
IntroductionandspreadofDENVandWNV,aswellasthepresenceofsuitableJEVvectorsinnon-endemicareas,willgreatlyincreasethenumberofindividualswhoarethreat-enedbythesepathogens.
VaccinedevelopmentDuetothelackofeffectivetherapyagainstmostflaviviruses,thefocusondevelopingpotentialvaccineshasescalated.
ConsideringtheincreasingprevalenceofWNVintheUSA,aswellastheglobalizationofDENV,developmentofsuc-cessfulvaccinesisimperativeforeffectivelypreventingflaviviral-associateddiseases(Chaoetal.
2012;Ehrenfeldetal.
2009;Sutteretal.
2000).
However,anysuchsuccessrequiresfurtherknowledgeofflaviviraldiseasepathogen-esis.
Identifyingviralandhostcomponentsimportantfordiseasedevelopmentmayleadtonewtargetsforvaccinesandtherapeuticagentsagainsttheviruses(HeinzandStiasny2012).
Theflavivirusgenomeencodesforapolyproteinthatispost-translationallycleavedintotenstructuralandnon-structuralcomponents(seedetailsinFig.
5).
Sinceallareimportantinthelifecycleandpathogenesisofthevirus,theyhavethecapacitytobeutilizedforvaccinedevelopment.
VaccinesforthethreestructuralproteinsC,prM,andEarealreadybeingdeveloped,withthemostemphasisonmultiva-lentvaccines,whichcontainmultipleimmunostimulatoryan-tigenicepitopesthatsimultaneouslygenerateprotectionagainstmultiplevirusesandserotypes(Brewooetal.
2012;Durbinetal.
2006;Ishikawaetal.
2011;Johnsonetal.
2002,2004).
Numerousstudieshavesuccessfullyproducedchime-ricvaccinescontainingtheviralenvelopeincludingtheprM/Eportionofthestructuralproteinaswellasregionsencompassingimportantnon-structuralcomponents(e.
g.
,NS1andNS5).
TheADEmechanismfacilitatingsecondaryandothersubsequentDENVinfectionsisstillachallengethatmustbeaddressedinthesevaccines.
Indeedthelimitedhet-erotypicprotectionagainstotherDENVserotypeshasslowedDENVvaccinedevelopment.
Productionofmultivalentvac-cineselicitingsimultaneousimmunogenicresponsesagainstallDENVserotypesmayleadtosuccessfulpreventionofDFandDHF.
Therehasbeenmodestsuccessindevelopinglive-attenuated,intertypicDENVchimerascontainingreplace-mentsoftheC,prM,E,and/orNS1regionsofDENV-4withthecorrespondingregionswithintheDENV-1orDENV-2genome(BrayandLai1991).
Monkeyssinglyormixinocu-latedwiththesechimerassuccessfullyshowedsimultaneousseroprotectionagainstDENV-1and-2whileatthesametimeproducingDENV-4-specificneutralizingantibodies(Brayetal.
1996).
Todate,however,therearenovaccinesinusethatcansimultaneouslytargetallfourDENVserotypes.
Therefore,creatingchimeric,tetravalentvaccinesprotectingagainstallfourDENVserotypescouldleadtopromisingprophylactictherapiesagainstthisemergingvirusandpreventthemoreseveredisease,DHF.
SanofiPasteurhasshownexcitingandgroundbreakingresultsinthedevelopmentofatetravalentvaccineagainstallfourDENVserotypes.
Currently,thevaccineisinphaseIIIclinicalstudywhichisbeingconductedinDENVendemicandnon-endemiccoun-tries(www.
dengue.
info).
SuccessfullyproducingtetravalentvaccineswillalleviatethedrawbackofADEassociatedwithDENVinfectionandprotectindividualsfromheterotypicinfectionwithotherDENVserotypes.
IMOJEV,meanwhile,isachimericJEVvaccinethatinte-gratedtheprMandEgenesofSA14-14-2(Liuetal.
2011)intotheyellowfevervaccinevector,YFV17D(Polandetal.
1981).
550J.
Neurovirol.
(2014)20:539–560Remarkably,thevaccinecarriesa100%seroconversionratewithgreaterthan85%seroprotection6monthspost-vaccina-tion,withcontinuedprotectionagainstheterologousserotypesupto5yearspost-inoculation(AppaiahgariandVrati2012a,b)aswellastheabilitytoprovidecontinuousprotectionafteronlyasingleimmunizationdose.
Moreinterestingisthere-portedcross-protectionofIMOJEVagainsttheJEV-relatedflavivirusessuchasMurrayValleyencephalitisvirusandWNV–Kunjinstrain;however,themechanismforthiscross-protectionhasnotyetbeenidentified(Lobigsetal.
2009).
Finally,animportantfeatureofIMOJEVistheincorporatedhigh-fidelityRNApolymerasewithintheYF17Dgenomewhichdecreasesthelikelihoodthattheviruswillundergogeneticmutationsandrevertbackintoitsvirulentstate(Pugachevetal.
2004).
TogetherthesepositiveattributesmakeIMOJEVahighlypromisingprophylaxisagainstJEVand,withfurtherdevelopment,againstotherrelatedflaviviruses.
ThepromisingresultsobservedduringthedevelopmentofmultivalentDENVvaccineshaveledtothedesignofotherviralchimerasintegratinggenomicmarkersfromJEV,WNV,orDENVwithinthepreviouslysuccessfulyellowfevervirusvaccinebackbone(Arroyoetal.
2004;Chambersetal.
1999,2003;Guirakhooetal.
1999,2000;Monathetal.
1999;Querecetal.
2006).
UnlikeWNVandDENV,therehasbeensignificantprogressinJEVvaccinedevelopmentsincetheinitialobservationofacquiredprotectionagainstJEVamongaccidentallyexposedlaboratoryworkers(HammonandSather1973;Pulmanausahakuletal.
2011).
Sincethen,thereisnowonevaccinecurrentlylicensedforuseintheUSA(IXIARO)alongwiththreevaccinesinJEVendemiccountries(e.
g.
,IMOJEV,SA14-14-2live-attenuatedvaccine,andthenowdiscontinuedJE-VAX).
FollowingthediscontinuationofJE-VAXduetosomereportedadversereactionstothevac-cine,IXIARO,acellculture-basedinactivatedvirusderivedfromtheSA-14-14-2strain,istheonlyinactivatedvaccinebeingproducedandadministeredtoday.
StilltherelativelylimitedeffectivenessofIXIAROcomparedwithlive-attenuatedvaccines(~80-90%)(HalsteadandThomas2011),reportedreactionstotheinactivatedvaccine(Nazarethetal.
1994;Ohtakietal.
1995;Plesner2003;PlesnerandRonne1997),andtherequirementofmultipledosesforcompleteprotection(Pugachevetal.
2003)haveledtosearchesformoreimmunogenicvaccineswithlessadverseeffects.
Productionoflive-attenuatedSA14-14-2vaccinein1988providedaseroconversionof80%afterasingledosewithsubsequentimmunizationsproducingefficacyratesof95-99%(Haseetal.
1993;Hennessyetal.
1996;Willsetal.
1992;Xinetal.
1988).
WhilenotaseffectiveasIMOJEV,furtherdevelopmentofSA14-14-2couldleadtoamoreeffectivelive-attenuatedvaccine.
SA14-14-2isanattenuatedstrainofJEV-SA14producedthroughserialpassagingoftheviruswithinhamsterkidneycells.
Duetothelowcostofitsproduction,aswellasminimalsideeffects,live-attenuatedSA14-14-2isbeingadministeredmoreprevalentlythaninactivatedvaccines(Schioleretal.
2007).
Indeedsinceitsapprovalforpublicuse,over200millionchildrenlivinginJEV-endemicareashavebeenimmunizedwiththelive-attenuatedvaccineandaccountsforover80%ofthetotalnumberofJEVvaccinations(AppaiahgariandVrati2012b;Liuetal.
2011).
WhiletherehavebeennoreportsregardingSA-14-14-2mutationalreversiontoitsvirulentstate,suchariskremainsapotentialdrawbackforthisandotherlive-attenuatedviruses.
Thereversionoflive-attenuatedvirusestotheiroriginalpathogenicstateandthesideeffects,includinghypersensitiv-ityagainstcomponentswithininactivatedvaccines,suggestthatthereisaneedfornewprophylactictreatmentsagainstJEVandotherflaviviruses.
Sincetheinitialconceptofusingplasmidsasimmunogenstwodecadesago,thedevelopmentofDNAvaccineshasadvanceddramatically,leadingtotheproductionofimmunogenicagentswhichareinvariousphasesofclinicaltrials(Ferraroetal.
2011).
Forinstance,DNAvaccineshavestartedtobedevelopedasprophylactictherapiesagainstavarietyofhumanpathogensincludingHIV(Ramirezetal.
2013),Plasmodiumfalciparum(Chuangetal.
2013),andMycobacteriumtuberculosis(Okadaetal.
2012)withpromisingresults.
InoculationsofthehostwithengineeredviralproteinexpressionplasmidsaresufficienttoelicitarobustcytotoxicCD8+andhelperCD4+Tlymphocyteresponseaswellastheproductionofprotectiveantibodiesagainsttheexpressedimmunogens(Alarconetal.
1999).
Thisexcitingtechnologyhassomeimportantimplicationsespecial-lyinthedevelopmentofDENVvaccinesasitcouldprovideconcurrentprotectionagainstallDENVserotypes,therebylimitingtheadverseeffectsofADE,ofwhichcurrentvaccineshavebeenunabletocircumvent.
Thisnovelapproachisbeingappliedtodevelopnewflavivirusvaccinesthattargetthesurface-exposedEandprMandNS1proteinswhichwerepreviouslyshowntobehighlyimmunogenicandelicitafavorableimmuneresponse(AhsanandGore2011;Azevedoetal.
2013;Costaetal.
2006a,b,2007;Davisetal.
2008b;Kulkarnietal.
2012;Luetal.
2013;Schneeweissetal.
2011).
ADNAvaccinetargetingDENV(designatedD1ME100)andWNVpreviouslyenteredinphase1ofclin-icaltrialsproducedfavorableresults(Beckettetal.
2011).
BothD1ME100andWNVvaccineselicitedstrong,long-lastingimmuneresponseinalltestsubjectsasquantifiedbyvirus-specificIgGandIgMproduction.
Evenmoreinterest-ing,despiteonlybeingimmunizedagainstDENV1,wasthattheD1ME100-vaccinatedsubjectsshowedsignificantIFNγresponsefollowinginoculationwithEproteinsderivedfromallfourDENVserotypes(Beckettetal.
2011).
TogetherthesedatashowgreatpromiseforDNAvaccinesinthepreventionofflavivirusinfectionsaswellasinfectionsbyanypathogenlackingavailabletreatmentsorvaccines.
J.
Neurovirol.
(2014)20:539–560551ViralinhibitorsInordertosuccessfullyinfectasuitablehost,avirusmustattachtothehost'sextracellularsurfaceandpenetrateintothecytosol.
There,theviralgenomeisunpackaged,transcribed,andtranslated.
Progenyvirusesarethenprocessedandpack-agedbyhostandviralmachineriestoproducemature,infec-tiousvirions.
Whilevaccineshavebeenhighlysuccessfulinpreventingimportanthumaninfectionssuchaspolioandsmallpox,researchforantiviraltherapeuticagents(i.
e.
,smallmoleculeinhibitors)isstillbeingpursuedforonemajorrea-son:identifyinghomologoustargetsacrossrelatedpathogenscanleadtothedesignofpharmaceuticaldrugsthatwillhelperadicatenumerousrelatedhumandiseases.
Closedepen-denceoftheflavivirallifecycleforhostcellularprocessesallowedresearcherstoutilizethesehostfunctionsintheirdesignofantiviralagents.
Indeednumerouscellularcompo-nentshavebeentargeted,includingviraladherencetothehostextracellularsurface(DeBurghgraeveetal.
2012;Schmidtetal.
2012),nucleicacidandproteinsynthesis(Noisakranetal.
2008;Ohetal.
2006;ParanjapeandHarris2007;Qingetal.
2009),intracellulartraffickingandsignaling(Hirschetal.
2005;Hongetal.
2013),andthehostimmuneresponse(Dikeakosetal.
2010;Mishraetal.
2009;Proudfootetal.
1999).
TheADEofDENVinfection,whichhashinderedtheproductionofsuccess-fulDENVvaccines,hasalsobeentheprimaryreasonforthedesignofmoreeffectiveviralinhibitors.
Onlyafewinhibitorsarecurrentlyavailablethatpreventflaviviralattachmentandentry.
DuetotheimportanceofEproteininflaviviralentryanditsnumerousbindingtargetsonhostcellmembranes,ithasbeenthefocusforviralentryinhibitors(Liaoetal.
2010;Schmidtetal.
2012).
Schmidtetal.
(2012)hasshownthataDENVEproteininhibitor,designated1662G07,anditsanalogscouldsuccessfullypre-ventDENV-2fusionwithhostendosomesatmicromolartosub-micromolarconcentrations(IC90=0.
75–2μM)whentest-edinvitro(Schmidtetal.
2012).
Inaddition,theinhibitorhasbeenshowntobeeffectiveagainstDENV-1and-2serotypes.
LCTA-949,areplicationinhibitorofhepatitisC(Obeidetal.
2011),isanothercompoundbeingdevelopedagainstflaviviralinfections,inparticularDENV(DeBurghgraeveetal.
2012).
TreatmentwithLCTA-949(12.
5μM)wasob-servedtopreventDENVentryintohostcellsbylimitingviralattachmenttothecellmembrane;however,thisinhibitoryactivityoccursonlywhenaddedconcurrentlywiththevirusinvitro.
Thissuggeststhatthebindingaffinityofthevirusforthehostcellmembranemaybegreaterthanviraladherencetotheinhibitor.
EvenmoreinterestingistheabilityofLCTA-949tocompetitivelyinhibittheattachmentofantibody-opsonizedDENVonthehostcellsurface.
Thissuggeststhecompound'spotentialinhibitoryactivityagainstADEofDENVinfection.
Duetoitsincapacitytoreversepre-existingDENVinfections,LCTA-949mustbedevelopedfurtherinorderforittobecomeclinicallyrelevant.
Inhibitionofotherflaviviralpathogens(i.
e.
,hepatitisCandyellowfeverviruses)andinterferencewithADE-DENVinfectionsmaymakethisnovelcompoundaviabletherapeuticagentagainstflaviviralinfectionsinthefuture.
Similartovirusattachmentandentry,post-translationalprocessingofthetranslatedviralgenomeisimportantforasuccessfulvirallifecycleandproductionofmature,infectiousvirions.
Indeedhostsignalasesandviralproteases(NS2bandNS3)havebeenshowntoberequiredforcleavageoftheflaviviralpolyproteinintobiologicallyactivecomponents(AppaiahgariandVrati2012b;Leyssenetal.
2000).
Inhibitingtheseproteaseshasbeenproposedtoabatevirusformationandmaturation(Filocamoetal.
1999).
Theimpor-tanceofviralproteasesduringflaviviruspathogenesis,aswellasinotherviralinfections,makesthemattractivetargetsfortherapeuticintervention.
Forinstance,oneanti-HIVtherapyinvolvestheuseofaproteaseinhibitor,Duranvir(Prezista;JanssenTherapeutics),whichtargetstheHIV-1PRproteaseimportantfortheprocessingoftheGag/Gag-polyprotein(PhungandYeni2011).
ThissameapproachisbeingappliedtowardsflavivirusesbytargetingtheNS3protease(Chappelletal.
2008;Lescaretal.
2008;Leyssenetal.
2000).
Infact,aproteaseinhibitor(Boceprevir;Merck)targetingtheNS3pro-teaseofHCVhasyieldedimpressiveresultsinclinicaltrials(Mannsetal.
2011).
Duringthestudy,HCVloadsamongtreatedpatientsweredrasticallyreducedascomparedwithnavesubjects.
TheactivityofBoceprevirhasnotyetbeentestedagainstotherrelatedflaviviruses.
Currentresults,how-ever,suggestthatBoceprevirandotherNS3-targetingprote-aseinhibitorsareexcellentcandidatesfortreatmentagainstDENV,WNV,andJEVinfections.
Anotherpotentialenzymetargetedforflavivirustherapyisguanylyltransferase(GTase)encodedwithintheNS5regionsoftheflavivirusgenome.
IthaspreviouslybeenshownthatGTases,inconcertwithviralRNAtriphosphatase,methytransferase,andnucleoside2′-O-methyltransferase,reg-ulateflavivirusgenometranslationandpreserveviralRNAintegritybymethylatingthe5′-endUTRoftheflavivirusgenome.
(Issuretal.
2009).
This,togetherwithitsconserva-tionamongrelatedflaviviruses,suggeststhatGTasescouldbetargetedfortherapeuticinterventionagainstmembersofthisvirusfamily(Bollatietal.
2010;Egloffetal.
2002;Geissetal.
2009).
IndeedinhibitionofGTaseactivityusingthecom-pound(E)-[3-[5-[4-tert-butylbenzylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl]propanoicacid(BG-323)preventedDENVandWNVreplication(Stahla-Beeketal.
2012).
Furthermore,thissamestudyshowedthatBG-323mayalsohaveanti-viralactivityagainsttheyellowfevervirus.
Itispossibletospeculatethatgivenitsbroadactivityagainstflaviviruses,BG-323couldbefurtherdevelopedintoasuc-cessfultherapyagainstflavivirusinfections,thatis,againsttheseverediseasesDFandDHF.
552J.
Neurovirol.
(2014)20:539–560Vectorcontrol:apotentialeffectivewaytoprotectthepopulationThespreadofmosquitovectorsisacriticaleventinthetransmissioncycleofDENV,WNV,andJEV.
Thus,preventingorreducingviraltransmissiondependsuponeitherthecontroloftheseinsectvectorsorinterruptionofthehu-man–vectorinteraction.
Someofthesemeasuresareincludedinthefollowinglistwhichprovidesacomprehensiveap-proachindesigningbetterpoliciesandprogramstodetect,eliminate,andattackthecriticalstagesofvectordevelopmentandviraltransmission:–Eliminationofpotentialhabitatsbycontrollinglocalen-vironmentsfacilitatingthesuccessfulreproductionofthemosquitoes—Theserecommendationsinvolvesimplestepstargetingtheearlystagesofvectordevelopmentsuchasbettermanagementofnaturalandman-madestagnantwatersourcesaswellaschemicalandbiologicalcontrolmethodsofmosquitopopulations(e.
g.
,insecticides,repellants,mosquitofish,andBacillusthuringiensis).
Thesesimplestepswillhelpreducethepresenceoflarvaeandadultmosquitopopulations,therebylimitingthepoten-tialcontactbetweeninfectedarthropodvectorsandhumans.
–Politicsandsocialadvocaciesareessentialfactorswhichallowtheimplementationofpolicieseducatingindivid-ualsabouttheglobalthreatofflaviviraldispersion.
Designingbetterpolicieswillprovidethegeneralpopu-lationandhealthcareworkersimportantmedicaltrainingandpreparationtofacetheseimportantviralthreats.
ThisisevenmoreimportantinareaspreviouslynotendemictoDENV,WNV,orJEVashealthworkersarenottypicallytrainedtoidentifytheseinfectiousdiseasesandthuspo-tentiallyconfusetheinfectionswithotherflu-likemala-dies.
Giventheincreasingglobalspreadofthesevirusesanditsmosquitovectors,dispersalofmedicalinformationaswellaspoliciesaimedatpreventingthefurtherspreadofthepathogensisnecessary.
–Abettercommunicationbetweenhealthorganizationsandthepopulationisessentialinpreventingdiseasespread.
ThespreadofWNV,DENV,andJEVmaybeinfluencedbythelackofinformationaboutviraltrans-mission,diseaseidentification,diseasetreatment,andinfectionstatistics.
Theseproblemsareexacerbatedamongresource-poorcountrieswhereflavivirusesaretypicallyfound.
Lackofresourcesandhealthservicescouldimpedethepublicdiffusionofeducationalinfor-mationimportantincontrollingeitherthevirusesoritsinsectvectors.
Propereducationwouldhelpalleviatethisproblemasitwillleadtoproductivediscussionsregardingthecontrolofthesepathogens,subsequentlypreventingviraltransmissionandthediseasesassociatedwiththeinfection.
ConcludingremarksandfuturedirectionsTheemergenceofWNVintheUSA,theworldwideexpan-sionofDENV,thecontinuousthreatsofJEV,andtherapiddispersalofsuitablemosquitovectorsmakeresearchinvolv-ingthesepathogensimperative.
Itisclearthatdrasticglobalchangesareaffectingthespreadofflavivirusesandtheirvectors.
Further,withtherapidlyexpandinghumanpopula-tionandtheencroachmentofthesevirusesinpreviouslynon-endemicareas,aglobalhealthprobleminvolvingthesevirus-esisimminent.
Thus,understandinghowthesevirusescausehumandiseasessuchasDHFisimperative.
Inaddition,theeverincreasingthreatsofnewinfectionsmakethedevelop-mentofnovel,effectivevaccinesandtherapeuticagentsvital.
Thesparse,conflictinginformationavailableregardingthepathogenesisofthesevirusesandthecelltypes,tissues,andorganstheyinfect,however,makeitdifficulttoproducesuc-cessfuldrugsagainstanyofthesepathogens.
Thus,untilsuc-cessfultreatmentsandmoreeffectivevaccinesareavailable,thebestmethodofeliminatingnewinfectionsinpublicandmedicalinstitutionsistostopviralvectorspreadandpreventbecomingbittenbymosquitoesthroughthecopioususeofrepellents.
ThemechanismsofCNSdysfunctioninducedbyflavivirusinfectionarepoorlyexploredorignored.
Thecelltargetsofflavivirusesandthereplicationpatternusedbythesevirusesarestillamatterofdebateandrequirefurtherinvestigation.
Identifyinghowflavivirusesalterhostcellphysiologywillprovidethebasisforunderstandingtheirpathogenesisandwillsubsequentlyleadtothedesignofmoreeffectivethera-peuticagentsagainsttheviruseswithintheCNS.
RecentadvancementsinresearchtechniquesandanimalmodelsandourdatausingprimaryhumanastrocytesandBMVECspro-videdcriticalevidence,suggestingthatflavivirusesareindeedneurotropic.
Further,identifyinghowthesevirusesregulateleukocyteactivationandCNStransmigrationaswellasdys-regulationofBBBfunctionleadingtoCNScompromiseandhumandiseaseiscriticallyimportant.
AcknowledgmentsThisworkwassupportedbyfundsfromthePublicHealthResearchInstitute(PHRI)andNationalInstitutesofMentalHealthgrantMH096625.
WethankthePHRIsharedfacilitiesatRutgersUni-versity,Newark,NJ,USA(http://phri.
org/facilities/facil_imaging.
asp).
WealsothankJonathanGuitoforcriticallyreadingandproof-readingthismanuscript.
ConflictofInterestTheauthorsdeclarethattheyhavenoconflictofinterest.
ReferencesAhsanMF,GoreMM(2011)ComparisonofimmuneresponsegeneratedagainstJapaneseencephalitisvirusenvelopeproteinexpressedbyDNAvaccinesundermacrophageassociatedversusubiquitousex-pressionpromoters.
VirolJ8:382J.
Neurovirol.
(2014)20:539–560553AlarconJB,WaineGW,McManusDP(1999)DNAvaccines:technologyandapplicationasanti-parasiteandanti-microbialagents.
AdvParasitol42:343–410AleyasAG,GeorgeJA,HanYW,RahmanMM,KimSJ,HanSB,KimBS,KimK,EoSK(2009)FunctionalmodulationofdendriticcellsandmacrophagesbyJapaneseencephalitisvirusthroughMyD88adaptormolecule-dependentand-independentpathways.
JImmunol183:2462–2474AleyasAG,HanYW,GeorgeJA,KimB,KimK,LeeCK,EoSK(2010)MultifrontassaultonantigenpresentationbyJapaneseencephalitisvirussubvertsCD8+Tcellresponses.
JImmunol185:1429–1441AmaralDC,RachidMA,VilelaMC,CamposRD,FerreiraGP,RodriguesDH,Lacerda-QueirozN,MirandaAS,CostaVV,CamposMA,KroonEG,TeixeiraMM,TeixeiraAL(2011a)Intracerebralinfectionwithdengue-3virusinducesmeningoenceph-alitisandbehavioralchangesthatprecedelethalityinmice.
JNeuroinflammation8:23AmaralDC,RachidMA,VilelaMC,CamposRD,FerreiraGP,RodriguesDH,Lacerda-QueirozN,MirandaAS,CostaVV,CamposMA,KroonEG,TeixeiraMM,TeixeiraAL(2011b)Intracerebralinfectionwithdengue-3virusinducesmeningoenceph-alitisandbehavioralchangesthatprecedelethalityinmice.
JNeuroinflammation8:23AndersKL,NguyetNM,ChauNV,HungNT,ThuyTT,leLienB,FarrarJ,WillsB,HienTT,SimmonsCP(2011)Epidemiologicalfactorsassociatedwithdengueshocksyndromeandmortalityinhospital-izeddenguepatientsinHoChiMinhCity,Vietnam.
AmJTropMedHyg84:127–134AndersonKB,GibbonsRV,ThomasSJ,RothmanAL,NisalakA,BerkelmanRL,LibratyDH,EndyTP(2011)PreexistingJapaneseencephalitisvirusneutralizingantibodiesandincreasedsymptomat-icdengueillnessinaschool-basedcohortinThailand.
PLoSNeglTropDis5:e1311AppaiahgariMB,VratiS(2012a)ClinicaldevelopmentofIMOJEV(R)—arecombinantJapaneseencephalitischimericvaccine(JE-CV).
ExpertOpinBiolTher12:1251–1263AppaiahgariMB,VratiS(2012b)ClinicaldevelopmentofIMOJEV(R)—arecombinantJapaneseencephalitischimericvaccine(JE-CV).
ExpertOpinBiolTher12:1251–1263AraujoFM,BrilhanteRS,CavalcantiLP,RochaMF,CordeiroRA,PerdigaoAC,MirallesIS,AraujoLC,AraujoRM,LimaEG,SidrimJJ(2011)Detectionofthedenguenon-structural1antigenincerebralspinalfluidsamplesusingacommerciallyavailableenzyme-linkedimmunosorbentassay.
JVirolMethods177:128–131AraujoF,NogueiraR,AraujoMdeS,PerdigaoA,CavalcantiL,BrilhanteR,RochaM,VilarDF,HolandaSS,BragaDdeM,SidrimJ(2012)Dengueinpatientswithcentralnervoussystemmanifestations,Brazil.
EmergInfectDis18:677–679ArroyoJ,MillerC,CatalanJ,MyersGA,RatterreeMS,TrentDW,MonathTP(2004)ChimeriVax-WestNileviruslive-attenuatedvaccine:preclinicalevaluationofsafety,immunogenicity,andeffi-cacy.
JVirol78:12497–12507AshourJ,Laurent-RolleM,ShiPY,Garcia-SastreA(2009)NS5ofdenguevirusmediatesSTAT2bindinganddegradation.
JVirol83:5408–5418AzeredoEL,Neves-SouzaPC,AlvarengaAR,ReisSR,Torrentes-CarvalhoA,ZagneSM,NogueiraRM,Oliveira-PintoLM,KubelkaCF(2010)Differentialregulationoftoll-likereceptor-2,toll-likereceptor-4,CD16andhumanleucocyteantigen-DRonperipheralbloodmonocytesduringmildandseveredenguefever.
Immunology130:202–216AzevedoAS,GoncalvesAJ,ArcherM,FreireMS,GallerR,AlvesAM(2013)ThesynergisticeffectofcombinedimmunizationwithaDNAvaccineandchimericyellowfever/denguevirusleadstostrongprotectionagainstdengue.
PLoSOne8:e58357BaiF,TownT,PradhanD,CoxJ,AshishLM,AndersonJF,FlavellRA,KruegerJK,KoskiRA,FikrigE(2007)AntiviralpeptidestargetingtheWestNilevirusenvelopeprotein.
JVirol81:2047–2055BeattyME,VorndamV,HunspergerEA,MunozJL,ClarkGG(2005)Travel-associateddengueinfections—UnitedStates,2001–2004.
MorbMortalWklyRep54:556–558BeckettCG,TjadenJ,BurgessT,DankoJR,TammingaC,SimmonsM,WuSJ,SunP,KochelT,RaviprakashK,HayesCG,PorterKR(2011)Evaluationofaprototypedengue-1DNAvaccineinaphase1clinicaltrial.
Vaccine29:960–968BhattS,GethingPW,BradyOJ,MessinaJP,FarlowAW,MoyesCL,DrakeJM,BrownsteinJS,HoenAG,SankohO,MyersMF,GeorgeDB,JaenischT,WintGR,SimmonsCP,ScottTW,FarrarJJ,HaySI(2013)Theglobaldistributionandburdenofdengue.
Nature496:504–507BhoopatL,BhamarapravatiN,AttasiriC,YoksarnS,ChaiwunB,KhunamornpongS,SirisanthanaV(1996a)Immunohistochemicalcharacterizationofanewmonoclonalantibodyreactivewithdenguevirus-infectedcellsinfrozentissueusingimmunoperoxidasetech-nique.
AsianPacJAllergyImmunollaunchedAllergyImmunolSocThail14:107–113BhoopatL,BhamarapravatiN,AttasiriC,YoksarnS,ChaiwunB,KhunamornpongS,SirisanthanaV(1996b)Immunohistochemicalcharacterizationofanewmonoclonalantibodyreactivewithdenguevirus-infectedcellsinfrozentissueusingimmunoperoxidasetech-nique.
AsianPacJAllergyImmunol14:107–113BollatiM,AlvarezK,AssenbergR,BarontiC,CanardB,CookS,CoutardB,DecrolyE,deLamballerieX,GouldEA,GrardG,GrimesJM,HilgenfeldR,JanssonAM,MaletH,ManciniEJ,MastrangeloE,MatteviA,MilaniM,MoureauG,NeytsJ,OwensRJ,RenJ,SeliskoB,SperoniS,SteuberH,StuartDI,UngeT,BolognesiM(2010)StructureandfunctionalityinflavivirusNS-proteins:perspectivesfordrugdesign.
AntiviralRes87:125–148BrayM,LaiCJ(1991)Constructionofintertypicchimericdenguevirusesbysubstitutionofstructuralproteingenes.
ProcNatlAcadSciUSA88:10342–10346BrayM,MenR,LaiCJ(1996)Monkeysimmunizedwithintertypicchimericdenguevirusesareprotectedagainstwild-typeviruschal-lenge.
JVirol70:4162–4166BrehinAC,MouriesJ,FrenkielMP,DadaglioG,DespresP,LafonM,CoudercT(2008)DynamicsofimmunecellrecruitmentduringWestNileencephalitisandidentificationofanewCD19+B220-BST-2+leukocytepopulation.
JImmunol180:6760–6767BrewooJN,KinneyRM,PowellTD,ArguelloJJ,SilengoSJ,PartidosCD,HuangCY,StinchcombDT,OsorioJE(2012)Immunogenicityandefficacyofchimericdenguevaccine(DENVax)formulationsininterferon-deficientAG129mice.
Vaccine30:1513–1520BrunkardJM,RoblesLopezJL,RamirezJ,CifuentesE,RothenbergSJ,HunspergerEA,MooreCG,BrussoloRM,VillarrealNA,HaddadBM(2007)Denguefeverseroprevalenceandriskfac-tors,Texas–Mexicoborder,2004.
EmergInfectDis13:1477–1483BucknerCM,LuersAJ,CalderonTM,EugeninEA,BermanJW(2006)Neuroimmunityandtheblood–brainbarrier:molecularregulationofleukocytetransmigrationandviralentryintothenervoussystemwithafocusonneuroAIDS.
JNeuroimmunePharm1:160–181BurkeT(1968)Denguehaemorrhagicfever:apathologicalstudy.
TransRSocTropMedHyg62:682–692CaminadeC,MedlockJM,DucheyneE,McIntyreKM,LeachS,BaylisM,MorseAP(2012)SuitabilityofEuropeanclimatefortheAsiantigermosquitoAedesalbopictus:recenttrendsandfuturescenarios.
JRSocInterface9:2708–2717ChambersTJ,NestorowiczA,MasonPW,RiceCM(1999)Yellowfever/Japaneseencephalitischimericviruses:constructionandbiologicalproperties.
JVirol73:3095–3101554J.
Neurovirol.
(2014)20:539–560ChambersTJ,LiangY,DrollDA,SchlesingerJJ,DavidsonAD,WrightPJ,JiangX(2003)Yellowfevervirus/dengue-2virusandyellowfevervirus/dengue-4viruschimeras:biologicalcharacterization,immunogenicity,andprotectionagainstdengueencephalitisinthemousemodel.
JVirol77:3655–3668ChaoDL,HalsteadSB,HalloranME,LonginiIMJr(2012)ControllingdenguewithvaccinesinThailand.
PLoSNeglTropDis6:e1876ChappellKJ,StoermerMJ,FairlieDP,YoungPR(2008)WestNilevirusNS2B/NS3proteaseasanantiviraltarget.
CurrMedChem15:2771–2784ChaseAJ,MedinaFA,Munoz-JordanJL(2011)ImpairmentofCD4+Tcellpolarizationbydenguevirus-infecteddendriticcells.
JInfectDis203:1763–1774ChaturvediUC,AgarwalR,ElbishbishiEA,MustafaAS(2000)Cytokinecascadeindenguehemorrhagicfever:implicationsforpathogenesis.
FEMSImmunolMedMicrobiol28:183–188CheeranMC,HuS,ShengWS,RashidA,PetersonPK,LokensgardJR(2005)DifferentialresponsesofhumanbraincellstoWestNilevirusinfection.
JNeurovirol11:512–524ChenSP(2012)MolecularphylogeneticandevolutionaryanalysisofJapaneseencephalitisvirusinChina.
EpidemiolInfect140:1637–1643ChenCJ,ChenJH,ChenSY,LiaoSL,RaungSL(2004)UpregulationofRANTESgeneexpressioninneurogliabyJapaneseencephalitisvirusinfection.
JVirol78:12107–12119ChuJJ,NgML(2003)Characterizationofa105-kDaplasmamembraneassociatedglycoproteinthatisinvolvedinWestNilevirusbindingandinfection.
Virology312:458–469ChuangI,SedegahM,CicatelliS,SpringM,PolhemusM,TammingaC,PattersonN,GuerreroM,BennettJW,McGrathS,GaneshanH,BelmonteM,FarooqF,AbotE,BananiaJG,HuangJ,NewcomerR,ReinL,LitilitD,RichieNO,WoodC,MurphyJ,SauerweinR,HermsenCC,McCoyAJ,KamauE,CummingsJ,KomisarJ,SutamihardjaA,ShiM,EpsteinJE,MaiolatesiS,ToshD,LimbachK,AngovE,Bergmann-LeitnerE,BruderJT,DoolanDL,KingCR,CarucciD,DuttaS,SoissonL,DiggsC,HollingdaleMR,OckenhouseCF,RichieTL(2013)DNAprime/adenovirusboostmalariavaccineencodingP.
falciparumCSPandAMA1inducessterileprotectionassociatedwithcell-mediatedim-munity.
PLoSOne8:e55571ClydeK,HarrisE(2006)RNAsecondarystructureinthecodingregionofdenguevirustype2directstranslationstartcodonselectionandisrequiredforviralreplication.
JVirol80:2170–2182ClydeK,KyleJL,HarrisE(2006)Recentadvancesindecipheringviralandhostdeterminantsofdenguevirusreplicationandpathogenesis.
JVirol80:11418–11431CostaSM,FreireMS,AlvesAM(2006a)DNAvaccineagainstthenon-structural1protein(NS1)ofdengue2virus.
Vaccine24:4562–4564CostaSM,PaesMV,BarretoDF,PinhaoAT,BarthOM,QueirozJL,ArmoaGR,FreireMS,AlvesAM(2006b)Protectionagainstden-guetype2virusinducedinmiceimmunizedwithaDNAplasmidencodingthenon-structural1(NS1)genefusedtothetissueplas-minogenactivatorsignalsequence.
Vaccine24:195–205CostaSM,AzevedoAS,PaesMV,SargesFS,FreireMS,AlvesAM(2007)DNAvaccinesagainstdenguevirusbasedonthens1gene:theinfluenceofdifferentsignalsequencesontheproteinexpressionanditscorrelationtotheimmuneresponseelicitedinmice.
Virology358:413–423CourageotMP,CatteauA,DespresP(2003)Mechanismsofdenguevirus-inducedcelldeath.
AdvVirusRes60:157–186DasS,BasuA(2008)Japaneseencephalitisvirusinfectsneuralprogen-itorcellsanddecreasestheirproliferation.
JNeurochem106:1624–1636DasS,MishraMK,GhoshJ,BasuA(2008)JapaneseencephalitisvirusinfectioninducesIL-18andIL-1betainmicrogliaandastrocytes:correlationwithinvitrocytokineresponsivenessofglialcellsandsubsequentneuronaldeath.
JNeuroimmunol195:60–72DavisAM,HaganKA,MatthewsLA,BajwaG,GillMA,GaleMJr,FarrarJD(2008a)BlockadeofvirusinfectionbyhumanCD4+Tcellsviaacytokinerelaynetwork.
JImmunol180:6923–6932DavisMR,LanganJN,JohnsonYJ,RitchieBW,VanBonnW(2008b)WestNilevirusseroconversioninpenguinsaftervaccinationwithakilledvirusvaccineoraDNAvaccine.
JZooWildlMed39:582–589DeBurghgraeveT,KapteinSJ,Ayala-NunezNV,MondotteJA,PastorinoB,PrintsevskayaSS,deLamballerieX,JacobsM,PreobrazhenskayaM,GamarnikAV,SmitJM,NeytsJ(2012)Ananalogueoftheantibioticteicoplaninpreventsflavivirusentryinvitro.
PLoSOne7:e37244DespresP,FrenkielMP,CeccaldiPE,DuarteDosSantosC,DeubelV(1998)Apoptosisinthemousecentralnervoussysteminresponsetoinfectionwithmouse-neurovirulentdengueviruses.
JVirol72:823–829DharakulT,KuraneI,BhamarapravatiN,YoksanS,VaughnDW,HokeCH,EnnisFA(1994)Denguevirus-specificmemoryTcellre-sponsesinhumanvolunteersreceivingaliveattenuateddenguevirustype2candidatevaccine.
JInfectDis170:27–33DikeakosJD,AtkinsKM,ThomasL,Emert-SedlakL,ByeonIJ,JungJ,AhnJ,WortmanMD,KukullB,SaitoM,KoizumiH,WilliamsonDM,HiyoshiM,BarklisE,TakiguchiM,SuzuS,GronenbornAM,SmithgallTE,ThomasG(2010)SmallmoleculeinhibitionofHIV-1-inducedMHC-Idown-regulationidentifiesatemporallyregulatedswitchinNefaction.
MolBiolCell21:3279–3292DinizJA,DaRosaAP,GuzmanH,XuF,XiaoSY,PopovVL,VasconcelosPF,TeshRB(2006)WestNilevirusinfectionofprimarymouseneuronalandneuroglialcells:theroleofastrocytesinchronicinfection.
AmJTropMedHyg75:691–696DurbinAP,McArthurJH,MarronJA,BlaneyJE,ThumarB,WanionekK,MurphyBR,WhiteheadSS(2006)rDEN2/4Delta30(ME),aliveattenuatedchimericdengueserotype2vaccineissafeandhighlyimmunogenicinhealthydengue-naiveadults.
HumVaccin2:255–260DurbinAP,VargasMJ,WanionekK,HammondSN,GordonA,RochaC,BalmasedaA,HarrisE(2008)Phenotypingofperipheralbloodmononuclearcellsduringacutedengueillnessdemonstratesinfec-tionandincreasedactivationofmonocytesinseverecasescomparedtoclassicdenguefever.
Virology376:429–435EfflerPV,PangL,KitsutaniP,VorndamV,NakataM,AyersT,ElmJ,TomT,ReiterP,Rigau-PerezJG,HayesJM,MillsK,NapierM,ClarkGG,GublerDJ(2005)Denguefever,Hawaii,2001–2002.
EmergInfectDis11:742–749EgloffMP,BenarrochD,SeliskoB,RometteJL,CanardB(2002)AnRNAcap(nucleoside-2′-O-)-methyltransferaseintheflavivirusRNApolymeraseNS5:crystalstructureandfunctionalcharacteri-zation.
EMBOJ21:2757–2768EhrenfeldE,ModlinJ,ChumakovK(2009)Futureofpoliovaccines.
ExpertRevVaccines8:899–905EugeninEA,BermanJW(2003)Chemokine-dependentmechanismsofleukocytetraffickingacrossamodeloftheblood–brainbarrier.
Methods29:351–361EugeninEA,BermanJW(2007)Gapjunctionsmediatehumanimmu-nodeficiencyvirus-bystanderkillinginastrocytes.
JNeurosciOffJSocNeurosci27:12844–12850EugeninEA,BermanJW(2013)CytochromeCdysregulationinducedbyHIVinfectionofastrocytesresultsinbystaderapoptosisofuninfectedastrocytesbyanIP3andcalcium-dependentmechanims.
JNeurochem127(5):644–651EugeninEA,GamssR,BucknerC,BuonoD,KleinRS,SchoenbaumEE,CalderonTM,BermanJW(2006a)SheddingofPECAM-1duringHIVinfection:apotentialroleforsolublePECAM-1inthepathogenesisofNeuroAIDS.
JLeukocBiol79:444–452J.
Neurovirol.
(2014)20:539–560555EugeninEA,OsieckiK,LopezL,GoldsteinH,CalderonTM,BermanJW(2006b)CCL2/monocytechemoattractantprotein-1mediatesenhancedtransmigrationofhumanimmunodeficiencyvirus(HIV)-infectedleukocytesacrosstheblood–brainbarrier:apotentialmechanismofHIV-CNSinvasionandNeuroAIDS.
JNeurosci26:1098–1106EugeninEA,ClementsJE,ZinkMC,BermanJW(2011)Humanimmu-nodeficiencyvirusinfectionofhumanastrocytesdisruptsblood–brainbarrierintegritybyagapjunction-dependentmechanism.
JNeurosciOffJSocNeurosci31:9456–9465FerraroB,MorrowMP,HutnickNA,ShinTH,LuckeCE,WeinerDB(2011)ClinicalapplicationsofDNAvaccines:currentprogress.
ClinInfectDis53:296–302FilocamoG,PaciniL,NardiC,BartholomewL,ScaturroM,DelmastroP,TramontanoA,DeFrancescoR,MigliaccioG(1999)SelectionoffunctionalvariantsoftheNS3-NS4AproteaseofhepatitisCvirusbyusingchimericsindbisviruses.
JVirol73:561–575FinkK,NgC,NkenfouC,VasudevanSG,vanRooijenN,SchulW(2009)Depletionofmacrophagesinmiceresultsinhigherdenguevirustitersandhighlightstheroleofmacrophagesforviruscontrol.
EurJImmunol39:2809–2821FreedmanDO,WeldLH,KozarskyPE,FiskT,RobinsR,vonSonnenburgF,KeystoneJS,PandeyP,CetronMS,GeoSentinelSurveillanceN(2006)Spectrumofdiseaseandrelationtoplaceofexposureamongillreturnedtravelers.
NEnglJMed354:119–130GagnonSJ,ZengW,KuraneI,EnnisFA(1996)Identificationoftwoepitopesonthedengue4viruscapsidproteinrecognizedbyaserotype-specificandapanelofserotype-cross-reactivehumanCD4+cytotoxicT-lymphocyteclones.
JVirol70:141–147GeissBJ,ThompsonAA,AndrewsAJ,SonsRL,GariHH,KeenanSM,PeersenOB(2009)AnalysisofflavivirusNS5methyltransferasecapbinding.
JMolBiol385:1643–1654GermanAC,MyintKS,MaiNT,PomeroyI,PhuNH,TzartosJ,WinterP,CollettJ,FarrarJ,BarrettA,KiparA,EsiriMM,SolomonT(2006)ApreliminaryneuropathologicalstudyofJapaneseencephalitisinhumansandamousemodel.
TransRSocTropMedHyg100:1135–1145GettsDR,MatsumotoI,MullerM,GettsMT,RadfordJ,ShresthaB,CampbellIL,KingNJ(2007)RoleofIFN-gammainanexperimen-talmurinemodelofWestNilevirus-inducedseizures.
JNeurochem103:1019–1030GettsDR,TerryRL,GettsMT,MullerM,RanaS,ShresthaB,RadfordJ,VanRooijenN,CampbellIL,KingNJ(2008)Ly6c+"inflammatorymonocytes"aremicroglialprecursorsrecruitedinapathogenicmannerinWestNilevirusencephalitis.
JExpMed205:2319–2337GhoshalA,DasS,GhoshS,MishraMK,SharmaV,KoliP,SenE,BasuA(2007)Proinflammatorymediatorsreleasedbyactivatedmicrog-liainducesneuronaldeathinJapaneseencephalitis.
Glia55:483–496GlassWG,LimJK,CholeraR,PletnevAG,GaoJL,MurphyPM(2005)ChemokinereceptorCCR5promotesleukocytetraffickingtothebrainandsurvivalinWestNilevirusinfection.
JExpMed202:1087–1098GrahamAS,PruszynskiCA,HribarLJ,DeMayDJ,TambascoAN,HartleyAE,FussellEM,MichaelSF,IsernS(2011)Mosquito-associateddenguevirus,KeyWest,Florida,USA,2010.
EmergInfectDis17:2074–2075GublerDJ(1998)Dengueanddenguehemorrhagicfever.
ClinMicrobiolRev11:480–496GublerDJ(2002)Epidemicdengue/denguehemorrhagicfeverasapublichealth,socialandeconomicprobleminthe21stcentury.
TrendsMicrobiol10:100–103GuirakhooF,ZhangZX,ChambersTJ,DelagraveS,ArroyoJ,BarrettAD,MonathTP(1999)Immunogenicity,geneticstability,andpro-tectiveefficacyofarecombinant,chimericyellowfever–Japaneseencephalitisvirus(ChimeriVax-JE)asalive,attenuatedvaccinecandidateagainstJapaneseencephalitis.
Virology257:363–372GuirakhooF,WeltzinR,ChambersTJ,ZhangZX,SoikeK,RatterreeM,ArroyoJ,GeorgakopoulosK,CatalanJ,MonathTP(2000)Recombinantchimericyellowfever–denguetype2virusisimmu-nogenicandprotectiveinnonhumanprimates.
JVirol74:5477–5485HalsteadSB(1988)Pathogenesisofdengue:challengestomolecularbiology.
Science239:476–481HalsteadSB,O'RourkeEJ(1977)Antibody-enhanceddenguevirusinfectioninprimateleukocytes.
Nature265:739–741HalsteadSB,ThomasSJ(2011)NewJapaneseencephalitisvaccines:alternativestoproductioninmousebrain.
ExpertRevVaccines10:355–364HalsteadSB,LanNT,MyintTT,ShweTN,NisalakA,KalyanaroojS,NimmannityaS,SoegijantoS,VaughnDW,EndyTP(2002)Denguehemorrhagicfeverininfants:researchopportunitiesig-nored.
EmergInfectDis8:1474–1479HammonWM,SatherGE(1973)Passiveimmunityforarbovirusinfec-tion.
I.
ArtificiallyinducedprophylaxisinmanandmouseforJapanese(B)encephalitis.
AmJTropMedHyg22:524–534HansenJE(2006)Avoidingclimatechange.
Science311:469–470HarrisE,HoldenKL,EdgilD,PolacekC,ClydeK(2006)Molecularbiologyofflaviviruses.
NovartisFoundSymp277:23–39,discus-sion40,71–3,251–3HaseT,DuboisDR,SummersPL,DownsMB,UsseryMA(1993)ComparisonofreplicationratesandpathogenicitiesbetweentheSA14parentandSA14-14-2vaccinestrainsofJapaneseencephalitisvirusinmousebrainneurons.
ArchVirol130:131–143HeinzFX,StiasnyK(2012)Flavivirusesandflavivirusvaccines.
Vaccine30:4301–4306HennessyS,LiuZ,TsaiTF,StromBL,WanCM,LiuHL,WuTX,YuHJ,LiuQM,KarabatsosN,BilkerWB,HalsteadSB(1996)Effectivenessoflive-attenuatedJapaneseencephalitisvaccine(SA14-14-2):acase–controlstudy.
Lancet347:1583–1586HirschAJ,MedigeshiGR,MeyersHL,DeFilippisV,FruhK,BrieseT,LipkinWI,NelsonJA(2005)TheSrcfamilykinasec-YesisrequiredformaturationofWestNilevirusparticles.
JVirol79:11943–11951HoberD,PoliL,RoblinB,GestasP,ChungueE,GranicG,ImbertP,PecarereJL,Vergez-PascalR,WattrePetal(1993)Serumlevelsoftumornecrosisfactor-alpha(TNF-alpha),interleukin-6(IL-6),andinterleukin-1beta(IL-1beta)indengue-infectedpatients.
AmJTropMedHyg48:324–331HoberD,DelannoyAS,BenyoucefS,DeGrooteD,WattreP(1996a)HighlevelsofsTNFRp75andTNFalphaindengue-infectedpatients.
MicrobiolImmunol40:569–573HoberD,ShenL,BenyoucefS,DeGrooteD,DeubelV,WattreP(1996b)EnhancedTNFalphaproductionbymonocytic-likecellsexposedtodenguevirusantigens.
ImmunolLett53:115–120HongW,ZhangR,DiZ,HeY,ZhaoZ,HuJ,WuY,LiW,CaoZ(2013)Designofhistidine-richpeptideswithenhancedbioavailabilityandinhibitoryactivityagainsthepatitisCvirus.
Biomaterials34:3511–3522HussmannKL,SamuelMA,KimKS,DiamondMS,FredericksenBL(2013)DifferentialreplicationofpathogenicandnonpathogenicstrainsofWestNileviruswithinastrocytes.
JVirol87:2814–2822ImrieA,ZhaoZ,BennettSN,KitsutaniP,LailleM,EfflerP(2006)MolecularepidemiologyofdengueinthePacific:introductionoftwodistinctstrainsofdenguevirustype-1[corrected]intoHawaii.
AnnTropMedParasitol100:327–336IshikawaT,WangG,WidmanDG,InfanteE,WinkelmannER,BourneN,MasonPW(2011)EnhancingtheutilityofaprM/E-expressingchimericvaccineforJapaneseencephalitisbyadditionoftheJEVNS1gene.
Vaccine29:7444–7455IssurM,GeissBJ,BougieI,Picard-JeanF,DespinsS,MayetteJ,HobdeySE,BisaillonM(2009)TheflavivirusNS5proteinisatrueRNA556J.
Neurovirol.
(2014)20:539–560guanylyltransferasethatcatalyzesatwo-stepreactiontoformtheRNAcapstructure.
RNA15:2340–2350JanJT,ChenBH,MaSH,LiuCI,TsaiHP,WuHC,JiangSY,YangKD,ShaioMF(2000)Potentialdenguevirus-triggeredapoptoticpath-wayinhumanneuroblastomacells:arachidonicacid,superoxideanion,andNF-kappaBaresequentiallyinvolved.
JVirol74:8680–8691JessieK,FongMY,DeviS,LamSK,WongKT(2004)Localizationofdenguevirusinnaturallyinfectedhumantissues,byimmunohisto-chemistryandinsituhybridization.
JInfectDis189:1411–1418JohnsonBW,ChambersTV,CrabtreeMB,BhattTR,GuirakhooF,MonathTP,MillerBR(2002)GrowthcharacteristicsofChimeriVax-DEN2vaccinevirusinAedesaegyptiandAedesalbopictusmosquitoes.
AmJTropMedHyg67:260–265JohnsonBW,ChambersTV,CrabtreeMB,GuirakhooF,MonathTP,MillerBR(2004)AnalysisofthereplicationkineticsoftheChimeriVax-DEN1,2,3,4tetravalentvirusmixtureinAedesaegyptibyreal-timereversetranscriptase-polymerasechainreac-tion.
AmJTropMedHyg70:89–97KawaguchiI,SasakiA,BootsM(2003)WhyaredenguevirusserotypessodistantlyrelatedEnhancementandlimitingserotypesimilaritybetweendenguevirusstrains.
ProcBiolSci270:2241–2247KhannaN,AgnihotriM,MathurA,ChaturvediUC(1991)NeutrophilchemotacticfactorproducedbyJapaneseencephalitisvirusstimu-latedmacrophages.
ClinExpImmunol86:299–303KhorCC,ChauTN,PangJ,DavilaS,LongHT,OngRT,DunstanSJ,WillsB,FarrarJ,VanTramT,GanTT,BinhNT,leTriT,leLienB,TuanNM,ThamNT,LanhMN,NguyetNM,HieuNT,VanNVCN,ThuyTT,TanDE,SakuntabhaiA,TeoYY,HibberdML,SimmonsCP(2011)Genome-wideassociationstudyidentifiessusceptibilitylocifordengueshocksyndromeatMICBandPLCE1.
NatGenet43:1139–1141KingAD,NisalakA,KalayanroojS,MyintKS,PattanapanyasatK,NimmannityaS,InnisBL(1999)Bcellsaretheprincipalcirculatingmononuclearcellsinfectedbydenguevirus.
SoutheastAsianJTropMedPublicHealth30:718–728KingNJ,ShresthaB,KessonAM(2003)Immunemodulationbyflaviviruses.
AdvVirusRes60:121–155KliksSC,NimmanityaS,NisalakA,BurkeDS(1988)Evidencethatmaternaldengueantibodiesareimportantinthedevelopmentofdenguehemorrhagicfeverininfants.
AmJTropMedHyg38:411–419KliksSC,NisalakA,BrandtWE,WahlL,BurkeDS(1989)Antibody-dependentenhancementofdenguevirusgrowthinhumanmono-cytesasariskfactorfordenguehemorrhagicfever.
AmJTropMedHyg40:444–451KrishnamurtiC,KalayanaroojS,CuttingMA,PeatRA,RothwellSW,ReidTJ,GreenS,NisalakA,EndyTP,VaughnDW,NimmannityaS,InnisBL(2001)Mechanismsofhemorrhageindenguewithoutcirculatorycollapse.
AmJTropMedHyg65:840–847KuhnRJ,ZhangW,RossmannMG,PletnevSV,CorverJ,LenchesE,JonesCT,MukhopadhyayS,ChipmanPR,StraussEG,BakerTS,StraussJH(2002)Structureofdenguevirus:implicationsforflavi-virusorganization,maturation,andfusion.
Cell108:717–725KulkarniR,SapkalG,GoreM(2012)EvaluationofJapaneseencepha-litisviruspolytopeDNAvaccinecandidateinBALB/cmice.
VirusRes170:118–125KumarR,TripathiS,TambeJJ,AroraV,SrivastavaA,NagVL(2008)DengueencephalopathyinchildreninNorthernIndia:clinicalfea-turesandcomparisonwithnondengue.
JNeurolSci269:41–48KuraneI,InnisBL,NisalakA,HokeC,NimmannityaS,MeagerA,EnnisFA(1989)HumanTcellresponsestodenguevirusantigens.
Proliferativeresponsesandinterferongammaproduction.
JClinInvest83:506–513KuraneI,BrintonMA,SamsonAL,EnnisFA(1991a)Denguevirus-specific,humanCD4+CD8-cytotoxicT-cellclones:multiplepatternsofviruscross-reactivityrecognizedbyNS3-specificT-cellclones.
JVirol65:1823–1828KuraneI,InnisBL,NimmannityaS,NisalakA,MeagerA,JanusJ,EnnisFA(1991b)ActivationofTlymphocytesindenguevirusinfections.
Highlevelsofsolubleinterleukin2receptor,solubleCD4,solubleCD8,interleukin2,andinterferon-gammainseraofchildrenwithdengue.
JClinInvest88:1473–1480Laurent-RolleM,BoerEF,LubickKJ,WolfinbargerJB,CarmodyAB,RockxB,LiuW,AshourJ,ShupertWL,HolbrookMR,BarrettAD,MasonPW,BloomME,Garcia-SastreA,KhromykhAA,BestSM(2010)TheNS5proteinofthevirulentWestNilevirusNY99strainisapotentantagonistoftypeIinterferon-mediatedJAK-STATsignaling.
JVirol84:3503–3515LeeCJ,LiaoCL,LinYL(2005)Flavivirusactivatesphosphatidylinositol3-kinasesignalingtoblockcaspase-dependentapoptoticcelldeathattheearlystageofvirusinfection.
JVirol79:8388–8399LeeDW,ChoeYJ,KimJH,SongKM,ChoH,BaeGR,LeeJK(2012)EpidemiologyofJapaneseencephalitisinSouthKorea,2007–2010.
IntJInfectDis16:e448–e452LescarJ,LuoD,XuT,SampathA,LimSP,CanardB,VasudevanSG(2008)Towardsthedesignofantiviralinhibitorsagainstflaviviruses:thecaseforthemultifunctionalNS3proteinfromdenguevirusasatarget.
AntiviralRes80:94–101LeyssenP,DeClercqE,NeytsJ(2000)PerspectivesforthetreatmentofinfectionswithFlaviviridae.
ClinMicrobiolRev13:67–82,TableofcontentsLiaoM,Sanchez-SanMartinC,ZhengA,KielianM(2010)Invitroreconstitutionrevealskeyintermediatestatesoftrimerformationbythedenguevirusmembranefusionprotein.
JVirol84:5730–5740LimaDM,dePaulaSO,FrancaRF,PalmaPV,MoraisFR,Gomes-RuizAC,deAquinoMT,daFonsecaBA(2011)ADNAvaccinecandi-dateencodingthestructuralprM/Eproteinselicitsastrongimmuneresponseandprotectsmiceagainstdengue-4virusinfection.
Vaccine29:831–838LinYL,HuangYL,MaSH,YehCT,ChiouSY,ChenLK,LiaoCL(1997)InhibitionofJapaneseencephalitisvirusinfectionbynitricoxide:antiviraleffectofnitricoxideonRNAvirusreplication.
JVirol71:5227–5235LinYW,WangKJ,LeiHY,LinYS,YehTM,LiuHS,LiuCC,ChenSH(2002)Virusreplicationandcytokineproductionindenguevirus-infectedhumanBlymphocytes.
JVirol76:12242–12249LinRJ,ChangBL,YuHP,LiaoCL,LinYL(2006)Blockingofinterferon-inducedJak-StatsignalingbyJapaneseencephalitisvirusNS5throughaproteintyrosinephosphatase-mediatedmechanism.
JVirol80:5908–5918LindenbachBD,PragaiBM,MontserretR,BeranRK,PyleAM,PeninF,RiceCM(2007)TheCterminusofhepatitisCvirusNS4AencodesanelectrostaticswitchthatregulatesNS5Ahyperphosphorylationandviralreplication.
JVirol81:8905–8918LindseyNP,StaplesJE,LehmanJA,FischerM(2010)SurveillanceforhumanWestNilevirusdisease—UnitedStates,1999–2008.
MMWRSurveillSumm59:1–17LiuX,YuY,LiM,LiangG,WangH,JiaL,DongG(2011)StudyontheprotectiveefficacyofSA14-14-2attenuatedJapaneseencephalitisagainstdifferentJEvirusisolatescirculatinginChina.
Vaccine29:2127–2130LiuS,LiX,ChenZ,ChenY,ZhangQ,LiaoY,ZhouJ,KeX,MaL,XiaoJ,WuY,ZhengX,LiJ,ChenQ(2013)ComparisonofgenomicandaminoacidsequencesofeightJapaneseencephalitisvirusisolatesfrombats.
ArchVirol158:2543–2552LobigsM,LarenaM,AlsharifiM,LeeE,PavyM(2009)LivechimericandinactivatedJapaneseencephalitisvirusvaccinesdifferintheircross-protectivevaluesagainstMurrayValleyencephalitisvirus.
JVirol83:2436–2445LuH,XuXF,GaoN,FanDY,WangJ,AnJ(2013)PreliminaryevaluationofDNAvaccinecandidatesencodingdengue-2prM/EJ.
Neurovirol.
(2014)20:539–560557andNS1:theirimmunityandprotectiveefficacyinmice.
MolImmunol54:109–114MalavigeGN,FernandoS,FernandoDJ,SeneviratneSL(2004)Dengueviralinfections.
PostgradMedJ80:588–601MannsMP,BourliereM,BenhamouY,PolS,BonaciniM,TrepoC,WrightD,BergT,CallejaJL,WhitePW,SternJO,SteinmannG,YongCL,KukoljG,SchererJ,BoecherWO(2011)Potency,safety,andpharmacokineticsoftheNS3/4AproteaseinhibitorBI201335inpatientswithchronicHCVgenotype-1infection.
JHepatol54:1114–1122MathewA,WestK,KalayanaroojS,GibbonsRV,SrikiatkhachornA,GreenS,LibratyD,JaiswalS,RothmanAL(2011)B-cellresponsesduringprimaryandsecondarydenguevirusinfectionsinhumans.
JInfectDis204:1514–1522MathurA,BharadwajM,KulshreshthaR,RawatS,JainA,ChaturvediUC(1988)Immunopathologicalstudyofspleendur-ingJapaneseencephalitisvirusinfectioninmice.
BrJExpPathol69:423–432MazzonM,JonesM,DavidsonA,ChainB,JacobsM(2009)DenguevirusNS5inhibitsinterferon-alphasignalingbyblockingsignaltransducerandactivatoroftranscription2phosphorylation.
JInfectDis200:1261–1270MedigeshiGR,LancasterAM,HirschAJ,BrieseT,LipkinWI,DefilippisV,FruhK,MasonPW,Nikolich-ZugichJ,NelsonJA(2007)WestNilevirusinfectionactivatestheunfoldedproteinresponse,leadingtoCHOPinductionandapoptosis.
JVirol81:10849–10860MentorNA,KuraneI(1997)DenguevirusinfectionofhumanTlym-phocytes.
ActaVirol41:175–176MiagostovichMP,dosSantosFB,deAraujoES,DiasJ,SchatzmayrHG,NogueiraRM(1997a)Diagnosisofdenguebyusingreversetranscriptase-polymerasechainreaction.
MemInstOswaldoCruz92:595–599MiagostovichMP,RamosRG,NicolAF,NogueiraRM,Cuzzi-MayaT,OliveiraAV,MarchevskyRS,MesquitaRP,SchatzmayrHG(1997b)Retrospectivestudyondenguefatalcases.
ClinNeuropathol16:204–208MishraMK,GhoshD,DusejaR,BasuA(2009)AntioxidantpotentialofminocyclineinJapaneseencephalitisvirusinfectioninmurineneu-roblastomacells:correlationwithmembranefluidityandcelldeath.
NeurochemInt54:464–470MohammedH,RamosM,ArmstrongJ,Munoz-JordanJ,Arnold-LewisKO,AyalaA,ClarkGG,TullES,BeattyME(2010a)AnoutbreakofdenguefeverinSt.
Croix(USVirginIslands),2005.
PLoSOne5:e13729MohammedHP,RamosMM,RiveraA,JohanssonM,Munoz-JordanJL,SunW,TomashekKM(2010b)Travel-associateddengueinfectionsintheUnitedStates,1996to2005.
JTravelMed17:8–14MonathTP,SoikeK,LevenbookI,ZhangZX,ArroyoJ,DelagraveS,MyersG,BarrettAD,ShopeRE,RatterreeM,ChambersTJ,GuirakhooF(1999)Recombinant,chimaericlive,attenuatedvac-cine(ChimeriVax)incorporatingtheenvelopegenesofJapaneseencephalitis(SA14-14-2)virusandthecapsidandnonstructuralgenesofyellowfever(17D)virusissafe,immunogenicandprotec-tiveinnon-humanprimates.
Vaccine17:1869–1882MongkolsapayaJ,DejnirattisaiW,XuXN,VasanawathanaS,TangthawornchaikulN,ChairunsriA,SawasdivornS,DuangchindaT,DongT,Rowland-JonesS,YenchitsomanusPT,McMichaelA,MalasitP,ScreatonG(2003)Originalantigenicsinandapoptosisinthepathogenesisofdenguehemorrhagicfever.
NatMed9:921–927MotaJ,Rico-HesseR(2011)Denguevirustropisminhumanizedmicerecapitulateshumandenguefever.
PLoSOne6:e20762MoussonL,DaugaC,GarriguesT,SchaffnerF,VazeilleM,FaillouxAB(2005)PhylogeographyofAedes(Stegomyia)aegypti(L.
)andAedes(Stegomyia)albopictus(Skuse)(Diptera:Culicidae)basedonmitochondrialDNAvariations.
GenetRes86:1–11Munoz-JordanJL,Sanchez-BurgosGG,Laurent-RolleM,Garcia-SastreA(2003)Inhibitionofinterferonsignalingbydenguevirus.
ProcNatlAcadSciUSA100:14333–14338NathansonN,ColeGA(1970)Immunosuppressionandexperimentalvirusinfectionofthenervoussystem.
AdvVirusRes16:397–448NazarethB,LevinJ,JohnsonH,BeggN(1994)SystemicallergicreactionstoJapaneseencephalitisvaccines.
Vaccine12:666NguyenTH,NguyenTL,LeiHY,LinYS,LeBL,HuangKJ,LinCF,DoQH,VuTQ,LamTM,YehTM,HuangJH,LiuCC,HalsteadSB(2005)Associationbetweensex,nutritionalstatus,severityofden-guehemorrhagicfever,andimmunestatusininfantswithdenguehemorrhagicfever.
AmJTropMedHyg72:370–374NoisakranS,DechtawewatT,AvirutnanP,KinoshitaT,SiripanyaphinyoU,PuttikhuntC,KasinrerkW,MalasitP,SittisombutN(2008)AssociationofdenguevirusNS1proteinwithlipidrafts.
JGenVirol89:2492–2500ObeidS,PrintsevskayaSS,OlsufyevaEN,DallmeierK,DurantelD,ZoulimF,PreobrazhenskayaMN,NeytsJ,PaeshuyseJ(2011)InhibitionofhepatitisCvirusreplicationbysemi-syntheticderiva-tivesofglycopeptideantibiotics.
JAntimicrobChemother66:1287–1294OgataA,NagashimaK,HallWW,IchikawaM,Kimura-KurodaJ,YasuiK(1991)Japaneseencephalitisvirusneurotropismisdependentonthedegreeofneuronalmaturity.
JVirol65:880–886OhW,YangMR,LeeEW,ParkKM,PyoS,YangJS,LeeHW,SongJ(2006)Jab1mediatescytoplasmiclocalizationanddeg-radationofWestNileviruscapsidprotein.
JBiolChem281:30166–30174OhtakiE,MatsuishiT,HiranoY,MaekawaK(1995)AcutedisseminatedencephalomyelitisaftertreatmentwithJapaneseBencephalitisvac-cine(Nakayama-YokenandBeijingstrains).
JNeurolNeurosurgPsychiatry59:316–317OkadaM,KitaY,NakajimaT,HashimotoS,NakataniH,NishimatsuS,NishidaY,KanamaruN,KanedaY,TakamoriY,McMurrayD,TanEV,CangML,SaundersonP,DelaCruzEC(2012)ThestudyofnovelDNAvaccinesagainsttuberculosis:inductionofpathogen-specificCTLinthemouseandmonkeymodelsoftuberculosis.
HumVaccinImmunother9OlaleyeOD,OmilabuSA,IlomechinaEN,FagbamiAH(1990)Asurveyforhaemagglutination-inhibitingantibodytoWestNilevirusinhumanandanimalserainNigeria.
CompImmunolMicrobiolInfectDis13:35–39PaesslerS,WalkerDH(2013)Pathogenesisoftheviralhemorrhagicfevers.
AnnuRevPathol8:411–440PalmerDR,SunP,CelluzziC,BisbingJ,PangS,SunW,MarovichMA,BurgessT(2005)Differentialeffectsofdenguevirusoninfectedandbystanderdendriticcells.
JVirol79:2432–2439PangT,CardosaMJ,GuzmanMG(2007)Ofcascadesandperfectstorms:theimmunopathogenesisofdenguehaemorrhagicfever–dengueshocksyndrome(DHF/DSS).
ImmunolCellBiol85:43–45ParanjapeSM,HarrisE(2007)Ybox-bindingprotein-1bindstothedenguevirus3′-untranslatedregionandmediatesantiviraleffects.
JBiolChem282:30497–30508ParquetMC,KumatoriA,HasebeF,MoritaK,IgarashiA(2001)WestNilevirus-inducedbax-dependentapoptosis.
FEBSLett500:17–24Pauvolid-CorreaA,MoralesMA,LevisS,FigueiredoLT,Couto-LimaD,CamposZ,NogueiraMF,daSilvaEE,NogueiraRM,SchatzmayrHG(2011)NeutralisingantibodiesforWestNilevirusinhorsesfromBrazilianPantanal.
MemInstOswaldoCruz106:467–474PeirisJS,AmerasingheFP,AmerasinghePH,RatnayakeCB,KarunaratneSH,TsaiTF(1992)JapaneseencephalitisinSriLanka—thestudyofanepidemic:vectorincrimination,porcineinfectionandhumandisease.
TransRSocTropMedHyg86:307–313PekoszA,PhillipsJ,PleasureD,MerryD,Gonzalez-ScaranoF(1996)InductionofapoptosisbyLaCrossevirusinfectionandroleof558J.
Neurovirol.
(2014)20:539–560neuronaldifferentiationandhumanbcl-2expressioninitspreven-tion.
JVirol70:5329–5335PetersenLR,MarfinAA(2005)ShiftingepidemiologyofFlaviviridae.
JTravelMed12(Suppl1):S3–S11PhungBC,YeniP(2011)Darunavir:aneffectiveproteaseinhibitorforHIV-infectedpatients.
ExpertRevAnti-InfectTher9:631–643PlesnerAM(2003)AllergicreactionstoJapaneseencephalitisvaccine.
ImmunolAllergyClinNAm23:665–697PlesnerAM,RonneT(1997)AllergicmucocutaneousreactionstoJapaneseencephalitisvaccine.
Vaccine15:1239–1243PolandJD,CalisherCH,MonathTP,DownsWG,MurphyK(1981)Persistenceofneutralizingantibody30–35yearsafterimmunizationwith17Dyellowfevervaccine.
BullWorldHealthOrgan59:895–900PriyadarshiniD,GadiaRR,TripathyA,GurukumarKR,BhagatA,PatwardhanS,MokashiN,VaidyaD,ShahPS,CeciliaD(2010)Clinicalfindingsandpro-inflammatorycytokinesindenguepatientsinWesternIndia:afacility-basedstudy.
PLoSOne5:e8709ProudfootAE,WellsTN,ClaphamPR(1999)Chemokinereceptors–futuretherapeutictargetsforHIVBiochemPharmacol57:451–463PugachevKV,GuirakhooF,TrentDW,MonathTP(2003)Traditionalandnovelapproachestoflavivirusvaccines.
IntJParasitol33:567–582PugachevKV,GuirakhooF,MitchellF,OcranSW,ParsonsM,JohnsonBW,KosoyOL,LanciottiRS,RoehrigJT,TrentDW,MonathTP(2004)Constructionofyellowfever/St.
Louisencephalitischimericvirusandtheuseofchimerasasadiagnostictool.
AmJTropMedHyg71:639–645PulmanausahakulR,RoytrakulS,AuewarakulP,SmithDR(2011)ChikungunyainSoutheastAsia:understandingtheemergenceandfindingsolutions.
IntJInfDisIJIDOffPublIntSocInfDis15:e671–e676QingM,YangF,ZhangB,ZouG,RobidaJM,YuanZ,TangH,ShiPY(2009)CyclosporineinhibitsflavivirusreplicationthroughblockingtheinteractionbetweenhostcyclophilinsandviralNS5protein.
AntimicrobAgentsChemother53:3226–3235QuerecT,BennounaS,AlkanS,LaouarY,GordenK,FlavellR,AkiraS,AhmedR,PulendranB(2006)YellowfevervaccineYF-17Dacti-vatesmultipledendriticcellsubsetsviaTLR2,7,8,and9tostimulatepolyvalentimmunity.
JExpMed203:413–424RadkeEG,GregoryCJ,KintzigerKW,Sauber-SchatzEK,HunspergerEA,GallagherGR,BarberJM,BiggerstaffBJ,StanekDR,TomashekKM,BlackmoreCG(2012)DengueoutbreakinKeyWest,Florida,USA,2009.
EmergInfectDis18:135–137RahmstorfS,CazenaveA,ChurchJA,HansenJE,KeelingRF,ParkerDE,SomervilleRC(2007)Recentclimateobservationscomparedtoprojections.
Science316:709RamirezLA,ArangoT,BoyerJ(2013)TherapeuticandprophylacticDNAvaccinesforHIV-1.
ExpertOpinBiolTher13:563–573RamosC,SanchezG,PandoRH,BaqueraJ,HernandezD,MotaJ,RamosJ,FloresA,LlausasE(1998)Denguevirusinthebrainofafatalcaseofhemorrhagicdenguefever.
JNeurovirol4:465–468RamosMM,MohammedH,Zielinski-GutierrezE,HaydenMH,LopezJL,FournierM,TrujilloAR,BurtonR,BrunkardJM,Anaya-LopezL,BanickiAA,MoralesPK,SmithB,Munoz-JordanJL,WatermanSH(2008)EpidemicdengueanddenguehemorrhagicfeverattheTexas–Mexicoborder:resultsofahousehold-basedseroepidemiologicsurvey,December2005.
AmJTropMedHyg78:364–369RaungSL,ChenSY,LiaoSL,ChenJH,ChenCJ(2005)TyrosinekinaseinhibitorsattenuateJapaneseencephalitisvirus-inducedneurotoxic-ity.
BiochemBiophysResCommun327:399–406RaungSL,ChenSY,LiaoSL,ChenJH,ChenCJ(2007)JapaneseencephalitisvirusinfectionstimulatesSrctyrosinekinaseinneu-ron/glia.
NeurosciLett419:263–268RauscherS,FlammC,MandlCW,HeinzFX,StadlerPF(1997)Secondarystructureofthe3′-noncodingregionofflavivirusgenomes:comparativeanalysisofbasepairingprobabilities.
RNA3:779–791RaviV,DesaiAS,ShenoyPK,SatishchandraP,ChandramukiA,Gourie-DeviM(1993)PersistenceofJapaneseencephalitisvirusinthehumannervoussystem.
JMedVirol40:326–329RaviV,ParidaS,DesaiA,ChandramukiA,Gourie-DeviM,GrauGE(1997)CorrelationoftumornecrosisfactorlevelsintheserumandcerebrospinalfluidwithclinicaloutcomeinJapaneseencephalitispatients.
JMedVirol51:132–136ReedKD,MeeceJK,HenkelJS,ShuklaSK(2003)Birds,migrationandemergingzoonoses:WestNilevirus,lymedisease,influenzaAandenteropathogens.
ClinMedRes1:5–12RestrepoBN,IsazaDM,SalazarCL,RamirezR,OspinaM,AlvarezLG(2008a)Serumlevelsofinterleukin-6,tumornecrosisfactor-alphaandinterferon-gammaininfantswithandwithoutdengue.
RevSocBrasMedTrop41:6–10RestrepoBN,RamirezRE,ArboledaM,AlvarezG,OspinaM,DiazFJ(2008b)Serumlevelsofcytokinesintwoethnicgroupswithdenguevirusinfection.
AmJTropMedHyg79:673–677Rigau-PerezJG,VorndamAV,ClarkGG(2001)ThedengueanddenguehemorrhagicfeverepidemicinPuertoRico,1994–1995.
AmJTropMedHyg64:67–74RobertsTK,EugeninEA,LopezL,RomeroIA,WekslerBB,CouraudPO,BermanJW(2012a)CCL2disruptstheadherensjunction:implicationsforneuroinflammation.
LabInvestig92:1213–1233RobertsTK,EugeninEA,LopezL,RomeroIA,WekslerBB,CouraudPO,BermanJW(2012b)CCL2disruptstheadherensjunction:implicationsforneuroinflammation.
LabInvestigJTechMethodsPathol92:1213–1233Rodenhuis-ZybertIA,WilschutJ,SmitJM(2010)Dengueviruslifecycle:viralandhostfactorsmodulatinginfectivity.
CellMolLifeSci67:2773–2786RoeK,KumarM,LumS,OrilloB,NerurkarVR,VermaS(2012a)WestNilevirus-induceddisruptionoftheblood–brainbarrierinmiceischaracterizedbythedegradationofthejunctionalcomplexproteinsandincreaseinmultiplematrixmetalloproteinases.
JGenVirology93:1193–1203RoeK,KumarM,LumS,OrilloB,NerurkarVR,VermaS(2012b)WestNilevirus-induceddisruptionoftheblood–brainbarrierinmiceischaracterizedbythedegradationofthejunctionalcomplexproteinsandincreaseinmultiplematrixmetalloproteinases.
JGenVirol93:1193–1203RothmanAL(2009)Tlymphocyteresponsestoheterologoussecondarydenguevirusinfections.
AnnNYAcadSci1171(Suppl1):E36–E41SabinAB(1952)ResearchondengueduringWorldWarII.
AmJTropMedHyg1:30–50SamuelMA,DiamondMS(2006)PathogenesisofWestNilevirusinfection:abalancebetweenvirulence,innateandadaptiveimmu-nity,andviralevasion.
JVirol80:9349–9360SarkariNB,ThackerAK,BarthwalSP,MishraVK,PrapannS,SrivastavaD,SarkariM(2012a)Japaneseencephalitis(JE)partII:14years'follow-upofsurvivors.
JNeurol259:58–69SarkariNB,ThackerAK,BarthwalSP,MishraVK,PrapannS,SrivastavaD,SarkariM(2012b)Japaneseencephalitis(JE).
PartI:clinicalprofileof1,282adultacutecasesoffourepidemics.
JNeurol259:47–57SchiolerKL,SamuelM,WaiKL(2007)VaccinesforpreventingJapaneseencephalitis.
CochraneDatabaseSystRevCD004263SchmidtAG,LeeK,YangPL,HarrisonSC(2012)Small-moleculeinhibitorsofdengue-virusentry.
PLoSPathog8:e1002627SchneeweissA,ChabierskiS,SalomoM,DelaroqueN,Al-RobaiyS,GrunwaldT,BurkiK,LiebertUG,UlbertS(2011)ADNAvaccineencodingtheEproteinofWestNilevirusisprotectiveandcanbeboostedbyrecombinantdomainDIII.
Vaccine29:6352–6357J.
Neurovirol.
(2014)20:539–560559ScreatonG,MongkolsapayaJ(2006)Tcellresponsesanddenguehaemorrhagicfever.
NovartisFoundSymp277:164–171,discussion171–6,251–3SharpTM,PillaiP,HunspergerE,SantiagoGA,AndersonT,VapT,CollinsonJ,BussBF,SafranekTJ,SotirMJ,JentesES,Munoz-JordanJL,ArguelloDF(2012)AclusterofdenguecasesinAmericanmissionariesreturningfromHaiti,2010.
AmJTropMedHyg86:16–22SimmonsCP,FarrarJJ,NguyenVV,WillsB(2012)Dengue.
NEnglJMed366:1423–1432SinghA,KulshreshthaR,MathurA(2000)AnenzymeimmunoassayfordetectionofJapaneseencephalitisvirus-inducedchemotacticcyto-kine.
JBiosci25:47–55SoaresCN,FariaLC,PeraltaJM,deFreitasMR,Puccioni-SohlerM(2006)Dengueinfection:neurologicalmanifestationsandcerebro-spinalfluid(CSF)analysis.
JNeurolSci249:19–24SolomonT,DungNM,VaughnDW,KneenR,ThaoLT,RaengsakulrachB,LoanHT,DayNP,FarrarJ,MyintKS,WarrellMJ,JamesWS,NisalakA,WhiteNJ(2000)Neurologicalmanifestationsofdengueinfection.
Lancet355:1053–1059SpindlerKR,HsuTH(2012a)Viraldisruptionoftheblood–brainbarrier.
TrendsMicrobiol20:282–290SpindlerKR,HsuTH(2012b)Viraldisruptionoftheblood–brainbarrier.
TrendsMicrobiol20:282–290SrikiatkhachornA,WichitS,GibbonsRV,GreenS,LibratyDH,EndyTP,EnnisFA,KalayanaroojS,RothmanAL(2012)DengueviralRNAlevelsinperipheralbloodmononuclearcellsareassociatedwithdiseaseseverityandpreexistingdengueimmunestatus.
PLoSOne7:e51335Stahla-BeekHJ,AprilDG,SaeediBJ,HannahAM,KeenanSM,GeissBJ(2012)Identificationofanovelantiviralinhibitoroftheflavivi-rusguanylyltransferaseenzyme.
JVirol86:8730–8739SuHL,LiaoCL,LinYL(2002)Japaneseencephalitisvirusinfectioninitiatesendoplasmicreticulumstressandanunfoldedproteinre-sponse.
JVirol76:4162–4171SutterRW,PrevotsDR,CochiSL(2000)Poliovirusvaccines.
Progresstowardglobalpoliomyelitiseradicationandchangingroutineim-munizationrecommendationsintheUnitedStates.
PediatrClinNAm47:287–308SwarupV,GhoshJ,DasS,BasuA(2008)Tumornecrosisfactorreceptor-associateddeathdomainmediatedneuronaldeathcontributestotheglialactivationandsubsequentneuroin-flammationinJapaneseencephalitis.
NeurochemInt52:1310–1321TomashekKM,RiveraA,Munoz-JordanJL,HunspergerE,SantiagoL,PadroO,GarciaE,SunW(2009)Descriptionofalargeisland-wideoutbreakofdengueinPuertoRico,2007.
AmJTropMedHyg81:467–474TungWH,TsaiHW,LeeIT,HsiehHL,ChenWJ,ChenYL,YangCM(2010)Japaneseencephalitisvirusinducesmatrixmetalloproteinase-9inratbrainastrocytesviaNF-kappaBsig-nallingdependentonMAPKsandreactiveoxygenspecies.
BrJPharmacol161:1566–1583UmareddyI,TangKF,VasudevanSG,DeviS,HibberdML,GuF(2008)DenguevirusregulatestypeIinterferonsignallinginastrain-dependentmannerinhumancelllines.
JGenVirol89:3052–3062vanderSchaarHM,RustMJ,ChenC,vanderEnde-MetselaarH,WilschutJ,ZhuangX,SmitJM(2008)Dissectingthecellentrypathwayofdenguevirusbysingle-particletrackinginlivingcells.
PLoSPathog4:e1000244VermaS,LoY,ChapagainM,LumS,KumarM,GurjavU,LuoH,NakatsukaA,NerurkarVR(2009)WestNilevirusinfectionmod-ulateshumanbrainmicrovascularendothelialcellstightjunctionproteinsandcelladhesionmolecules:transmigrationacrosstheinvitroblood–brainbarrier.
Virology385:425–433WilliamsDW,EugeninEA,CalderonTM,BermanJW(2012)Monocytematuration,HIVsusceptibility,andtransmigrationacrossthebloodbrainbarrierarecriticalinHIVneuropathogenesis.
JLeukocBiol91:401–415WillsMR,SilBK,CaoJX,YuYX,BarrettAD(1992)AntigeniccharacterizationoftheliveattenuatedJapaneseencephalitisvaccinevirusSA14-14-2:acomparisonwithisolatesoftheviruscoveringawidegeographicarea.
Vaccine10:861–872XinYY,MingZG,PengGY,JianA,MinLH(1988)Safetyofalive-attenuatedJapaneseencephalitisvirusvaccine(SA14-14-2)forchil-dren.
AmJTropMedHyg39:214–217YuIM,ZhangW,HoldawayHA,LiL,KostyuchenkoVA,ChipmanPR,KuhnRJ,RossmannMG,ChenJ(2008)StructureoftheimmaturedenguevirusatlowpHprimesproteolyticmaturation.
Science319:1834–1837ZanottoPM,GouldEA,GaoGF,HarveyPH,HolmesEC(1996)Populationdynamicsofflavivirusesrevealedbymolecularphylog-enies.
ProcNatlAcadSciUSA93:548–553ZhangY,ZhangW,OgataS,ClementsD,StraussJH,BakerTS,KuhnRJ,RossmannMG(2004)ConformationalchangesoftheflavivirusEglycoprotein.
Structure12:1607–1618ZhouJ,StohlmanSA,HintonDR,MartenNW(2003)Neutrophilspromotemononuclearcellinfiltrationduringviral-inducedenceph-alitis.
JImmunol170:3331–3336ZybertIA,vanderEnde-MetselaarH,WilschutJ,SmitJM(2008)Functionalimportanceofdenguevirusmaturation:infectiousprop-ertiesofimmaturevirions.
JGenVirol89:3047–3051560J.
Neurovirol.
(2014)20:539–560