918年,由甲型H1N1流感病毒引發(fā)的“西班牙流感”爆發(fā)流行,在全球超過(guò)5億人感染,造成5千萬(wàn)到1億人死亡,死亡人數(shù)甚至超過(guò)了第一次世界大戰(zhàn)和第二次世界大戰(zhàn)死亡人數(shù)的總和,可謂是世界歷史上最嚴(yán)重的流行病疫情。而今,在“西班牙流感”暴發(fā)100周年之際,中國(guó)疾病預(yù)防控制中心主任高福院士應(yīng)邀為國(guó)際頂級(jí)學(xué)術(shù)期刊《細(xì)胞》撰寫(xiě)評(píng)述文章“From‘A’IVto‘Z’IKV:AttacksfromEmergingandRe-emergingPathogens”,用生動(dòng)的語(yǔ)言和詳實(shí)的數(shù)據(jù)系統(tǒng)地評(píng)述了全球新發(fā)突發(fā)傳染病形勢(shì)及應(yīng)對(duì)策略。
該文對(duì)于新發(fā)突發(fā)病原進(jìn)行了歷史性回顧,尤其開(kāi)篇從今年流感流行、紀(jì)念1918大流行100年作為切入點(diǎn),然后延伸到包括中東呼吸綜合征(MERS)、埃博拉在內(nèi)的新發(fā)突發(fā)傳染病,還重點(diǎn)介紹了發(fā)現(xiàn)很早、但是直到最近幾年才對(duì)人引起嚴(yán)重感染的寨卡。高福院士巧妙地用了從A(禽流感)到Z(寨卡)這樣的題目,既體現(xiàn)了新發(fā)再發(fā)病毒的不斷涌現(xiàn)及暴發(fā)的不確定性,又預(yù)示了人類最終能戰(zhàn)勝病毒。
Figure1HumanInfectionswithSubtypesofInfluenzaAViruses
在對(duì)抗這些新發(fā)突發(fā)病原的研究和防控過(guò)程中,我們看到了我國(guó)科學(xué)家近年來(lái)在傳染病防控領(lǐng)域所取得的驕人成績(jī),也看到了我國(guó)基礎(chǔ)研究及防控隊(duì)伍的不斷壯大及大國(guó)的責(zé)任和擔(dān)當(dāng)。最后,高福院士提出,控制傳染病的兩個(gè)重要要素:持續(xù)監(jiān)測(cè)與基礎(chǔ)研究。病毒傳播是沒(méi)有國(guó)界的,因此必須開(kāi)展國(guó)際合作。高院士呼吁全球的科學(xué)家、臨床醫(yī)生及公共衛(wèi)生專家等一起來(lái)攻克新發(fā)突發(fā)病原,并著重介紹了即將全面啟動(dòng)的全球病毒組計(jì)劃(GlobalViromeProject,GVP)、建立非洲CDC網(wǎng)絡(luò)等戰(zhàn)略部署,將對(duì)新發(fā)突發(fā)病原發(fā)起“主動(dòng)出擊、全面出擊”,主動(dòng)鑒定出病毒威脅,并采取必要的措施來(lái)預(yù)防下一次的大流行病。
高院士呼吁啟動(dòng)全球病毒組項(xiàng)目
此外,高院士對(duì)由世界銀行、世界衛(wèi)生組織以及日本和德國(guó)政府共同發(fā)起的流行病應(yīng)急融資基金(PEF),以及由挪威政府、比爾和梅林達(dá).蓋茨基金會(huì)、惠康信托基金會(huì)和世界經(jīng)濟(jì)論壇共同建立的流行病預(yù)防創(chuàng)新聯(lián)盟(CEPI)給予高度評(píng)價(jià)。這類創(chuàng)新的全球性融資機(jī)制,將有效保護(hù)全世界免遭致命性流行病影響,并加速
疫苗研發(fā)進(jìn)程。人類需要不斷認(rèn)知病原。高院士指出對(duì)病毒的致病性、跨種傳播等深入的基礎(chǔ)研究是傳染病有效防控的根本,也亟待更多的關(guān)注和基金資助。
中國(guó)微生物學(xué)會(huì)病毒學(xué)專業(yè)委員會(huì)主任委員郭德銀評(píng)論文章雖然篇幅不長(zhǎng),但高屋建瓴,視野寬廣,信息豐富,重點(diǎn)突出。文章內(nèi)容構(gòu)思巧妙,題目“從A(禽流感)到Z(寨卡)”寓意深長(zhǎng),一是說(shuō)明新發(fā)突發(fā)病毒的多樣性和復(fù)雜性,二是意指從對(duì)病原監(jiān)測(cè)到完全控制病原的期望。文章首先重點(diǎn)介紹當(dāng)前正在流行并不斷新發(fā)再發(fā)的流感病毒的起因、危害和防控措施,然后依次介紹SARS和MERS冠狀病毒、埃博拉病毒、寨卡病毒等的歷史與現(xiàn)狀,強(qiáng)調(diào)了活禽市場(chǎng)關(guān)閉、新技術(shù)應(yīng)用(如高通量基因組測(cè)序)、國(guó)內(nèi)外合作、早期檢測(cè)與持續(xù)監(jiān)測(cè)、尤其是基礎(chǔ)研究在防控新發(fā)突發(fā)病毒方面的重要性。
高福院士在文章中指出經(jīng)過(guò)SARS之后,中國(guó)已經(jīng)建立起高效的病原監(jiān)測(cè)與防控體系。而中國(guó)疾病預(yù)防控制中心作為政府舉辦的實(shí)施疾病預(yù)防控制與公共衛(wèi)生技術(shù)管理和服務(wù)的國(guó)家級(jí)專業(yè)機(jī)構(gòu),自成立以來(lái)通過(guò)不斷鞏固相關(guān)基礎(chǔ)研究,大力推進(jìn)疾病預(yù)防控制的應(yīng)用研究,在重大傳染病的防治和疾病預(yù)防控制的基礎(chǔ)、前沿技術(shù)研究方面取得了豐碩成果,并以此為支撐,在疾控基礎(chǔ)平臺(tái)體系建設(shè)、新發(fā)突發(fā)傳染病應(yīng)對(duì)、重大傳染病和慢性病防控等方面取得了突出成績(jī)。
高福院士在文中呼吁要銘記歷史教訓(xùn),避免悲劇再次上演,要持續(xù)加強(qiáng)在基礎(chǔ)研究方面的投入,以此來(lái)積極促進(jìn)公共健康政策和創(chuàng)新合作舉措的有效施行。該文章對(duì)于我國(guó)病原學(xué)研究和傳染病防控具有重要價(jià)值,對(duì)進(jìn)一步推動(dòng)“健康中國(guó)”戰(zhàn)略、“一帶一路”倡議以及構(gòu)建人類命運(yùn)共同體具有重要意義。
From“A”IVto“Z”IKV:AttacksfromEmergingandRe-emergingPathogens
GeorgeF.Gao
100yearsaftertheinfamous“Spanishflu”pandemic,the2017–2018fluseasonhasbeensevere,withnumerousinfectionsworldwide.Inbetween,therehavebeencontinuous,relentlessattacksfrom(re-)emergingviruses.Tofullyunderstandviralpathogenesisanddevelopeffectivemedicalcountermeasures,wemuststrengthencurrentsurveillanceandbasicresearchefforts.
Thisyearmarksthecentenaryofthe“Spanishflu”pandemic,themostdevastatingviralpandemicinhistorycausedbyanH1N1influenzaAvirusthatinfectedover500millionandkilledbetween50and100millionpeople.Weknowtoexpectafluseasoneveryyear;thequestionisalwayshowsevereitwillbe.Withhighnumbersofinfluenzainfectionsreportedworldwideduringthisseason,weareagainremindedofthepublichealththreatstemmingfromapotentialinfluenzapandemic.TheUSCentersforDiseaseControlandPrevention(CDC)reportedthatthisisthefirsttimeinthepast15yearsthatallstatesintheentirecontinentalUSAhavereportedwidespreadfluactivityduringthesameweek.InChina,thereportednumberofflucaseshaveincreasedover2-foldcomparedtothefluseasonsinthepastseveralyears—thesecond-highestrecordednumber,justafterthe2009pandemicH1N1(pH1N1)—andmanypatientshavebeenhospitalizedwithsevereclinicalsymptoms.Theseeventshaveraisedconcernsthatweareindangerofanotherflupandemic.Circulatingfluvirusesarequitediversethisyear—includingthe“swineflu”2009-pH1N1,H3N2,andinfluenzaB/VictoriaandB/Yamagata—andarespreadacrossvariousgeographicallocations.TheH3N2subtypeisdominantintheUKandtheUSA,butamixedpoolofpH1N1,H3N2,andinfluenzaB/Yamagata,witha
smallportionofB/Victoria,havebeenreportedinChina.Auniversalinfluenzavaccinetocombatsuchmutation-pronevirusesisurgentlyneededyetstillfarfromreach,despitetheglobalefforts.Despitebesteffortstoanticipatetheemergentstrains,vaccinesvaryfromyeartoyearintermsofefficacy,withthisyear’sprovidingonlymoderateprotection.
HumaninfectionswithdifferentsubtypesofavianinfluenzaAviruses(AIVs)havebeenconsistentlyreportedsinceH5N1AIVwasreportedinHongKongduring1997(Yuenetal.,1998).InfectionswithAIVtypicallyresultinhighcasefatalityrates(CFRs)rangingfrom~30%to~70%,andatleast14influenzaAvirussubtypes—includingthethreeseasonalfluviruses,H1N1,H2N2,andH3N2—havereportedlyinfectedhumanstodate(Figure1).Ofnote,influenzaAvirushasasegmentedgenomewith8genomicsegmentsencodingatleast10–16proteins,twoofwhicharehemagglutinin(HA)andneuraminidase(NA).Therearecurrently16(+2)HAgenesand9(+2)NAgenes(+2meanstwomoreHAorNAfrombat-derivedinfluenza-likeviruses,forwhichonlygenomicsequencesareavailable,butnoalivevirushasyetbeenisolated;Wuetal.,2014).ThecombinationofHAandNAwouldtheoreticallyyield144subtypesofHxNyviruses.Duetothemigratorybirds’travelandlivepoultrytrade,whichincludesthetransportofpoultryandoperationoflivepoultrymarkets(LPMs)throughoutChinaandSoutheastAsia(Gao,2014),weshouldexpectmorehumaninfectionswithAIVsinthefuture.AIVsmaysupplygenomicsegmentsforreassortmentwithcirculatingseasonalinfluenzavirusestogenerateanovelpathogenwithhighCFRandpandemicpotential.Aswecan’tyeteradicateseasonalflu,effortstochangethetraditionallivepoultrytrade—forexample,thetraditionalLPMs—inordertorestricttheflowofdomesticpoultrymigrationmayhelpdecreasetheprobabilityoftheemergenceofnovelAIVsubtypes,eventhepotentialpandemicviruses.
ThenumbersofhumancasesinfectedbydifferentsubtypesofinfluenzaAvirusreportedworldwideareshowninhistogram(WHO,2017a).Thexaxispresentsthetimepoints(year)ofthefirstreportedcaseforeachsubtypevirus.Theyaxispresentsthetotalnumbersofreportedhumancasestodate.Thecasenumbersofhuman-infectingH1N1,H2N2,andH3N2areextraordinarilylargeandarenotavailableforexactcountsduetoinfluenzapandemicssuchasthe1918H1N1Spanishflu,1957H2N2Asianflu,and1968H3N2HongKongflu.
Fluisn’talone.Coronavirusisanotherfamilyofemergingpathogenswithpublichealthconcern.Adevastatingbutquicklyconqueredoutbreakofsevereacuterespiratorysyndromecoronavirus(SARS-CoV)during2003transformedChina’sapproachtooutbreakcontrol.Asophisticatedsurveillancesystemhassincebeenputintoplace.Whileprimarilygovernmentled,thereisextensivecollaborationwithvariousinstitutesintheacademic,industry,andhealthcarefieldstoproduceawide-ranging,comprehensivenetworkthatissueswarningsofanimpendingoutbreakattheearliestopportunity.AsexemplifiedbytheChineseAcademyofSciencesCenterforInfluenzaResearchandEarly-warning(CASCIRE)network,inadditiontoChineseNationalInfluenzaCenter/WHOCollaboratingCenterforReferenceandResearchonInfluenzaunderChinaCDC,suchasystemcandrivebasic,applied,andtranslationalresearchoninfectiousdiseasecontrolandprevention(Bietal.,2017).Arelatedcoronavirus,theMiddleEastrespiratorysyndromecoronavirus(MERS-CoV),emergedintheMiddleEastduring2012andhasonoccasioncausedsporadicinfectionswithimportedcasesfromreturningtravelers,someofwhichgoontoinfectothers.OnesuchinstancewastheimportationofaMERS-CoVcaseintoChinafromSouthKoreaduring2015(Suetal.,2015),inwhichthetravelerwaspromptlyidentifiedandquarantined,preventingfurtherinfections.DuetotheongoingnatureoftheMERS-CoVoutbreak,wearelikelytoencountermorecoronavirusinfectionsinthefuture.Preparationsshouldbemadeaccordinglythroughthedevelopmentofbothvaccinesandantivirals.
Ebolavirus(EBOV),firstidentifiedinCentralAfricaduring1976,unexpectedlystruckWestAfricaduring2013–2015,impactingseveralcountriesinNorthAmerica,Europe,andAfrica.Afterearlierincidents,effortswereunderwaytodevelopvaccinecandidates;however,thesewerechallenged,astheviruswasatfirstsuspectedtohaveahighermutationratethatmightnegativelyimpacttheefficacyoftheEBOVvaccinecandidatesunderclinicaltrials(Gireetal.,2014).Toaddressthisquestiondirectly,atotalof175whole-genomesequenceswereobtainedfromviralisolates,andthemutationratewasdeterminedtobesimilartothatofpastEBOVoutbreaks(Tongetal.,2015).Therefore,currentexperimentalvaccinesshouldstillbeefficacious.Duringthisepidemic,applicationofgenomicsequencingtechnologygreatlyfacilitateddiseasecontrol.Molecularepidemiologyandpathogenesisstudies,inadditiontothedevelopmentofeffectiveantivirals,suchastheZMappantibodycocktailandthevesicular-stomatitis-virus(VSV)-andadenovirus(Ad5,chAd3)-basedvaccines,werethekeymeasuresfortheeffectivecontrolofthesepathogens.
WhiletheworldwasstillcelebratingthesuccessoffinallyconqueringEBOVafteraprotracted2-yearbattle,Zikavirus(ZIKV)struckwiththefirstcasesreportedinBrazilaftersmalloutbreakspreviouslyreportedinMicronesia(YapIsland)andFrenchPolynesiain2007and2013,respectively(Figure2).Asanobscurepathogen(butknowntohumanssince1947),theZIKVisolatesfromthe2015–2016epidemicwerefoundtopossessnewcharacteristics(Grubaughetal.,2018).Thevirusquicklyspreadgeographicallywithatleast84countries/regionsaffected(Figure2).AcoordinatedglobalresponseeventuallyledtotheconclusionoftheepidemicinNovember2016,butlong-termcomplicationsstemmingfromZIKVinfectionsareyetbeingreportedfromconvalescentpatients.
LocationswherebigeventsofZikavirusinfectionoccurredwereindicatedinred.Theseeventsaredescribedinboxesandnumberedaccordingtothetimesequence.ThedashedarrowlinesrepresentthespreadingroutesofZikavirusduringthe2015–2016outbreak.RegionswithevidenceofZikavirustransmissionarecoloredinyellow,exceptforthefivered-coloredonesasmentionedabove.Chinaiscoloredinlightyellowduetotheimportedcasesin2016andtheisolationofZikavirusinlocalvector,althoughnotinthe84countrieswithZikavirustransmissionaccordingtotheWHOclassification(WHO,2017b).
AftertheZIKVepidemic,outbreaksofyellowfevervirus(YFV)occurredacrossAngolaandBrazilin2017.TheviruswasimportedtoChinaasChineseworkersreturnedfromAngola(Chenetal.,2016).Almostsimultaneously,RiftValleyfevervirus(RVFV)wasalsoimportedintoChinafromAngolathroughareturningtraveler.Theseeventshighlightedthedifficultyinaccuratelypredictingthetimeandlocation,aswellastheidentity,ofthecausativepathogenbehindthenextoutbreak.Indeed,EBOVandZIKVwerebothconsideredneglected,tropicalre-emergingpathogens,SARS-CoVandMERS-CoVwerenovel,emergingpathogens,andinfluenzavirusesweretypicallyre-emergingpathogenswithnewpropertiesderivedfromgeneticevolutionandreassortments.
Amyriadofcontributingfactorssuchasurbanization,globalization,andclimatechangewillimpactthepathogenicityandtransmissionofcertainpathogens,aswellasthedistributionoftheirreservoirhosts.Thisrealityplacesadditionalemphasisontheimportanceofproactivecountermeasures,suchaspathogensurveillanceandvaccinedevelopment,aswellastheneedforreactivecountermeasures,suchasantiviraltherapy.
Asacommunityofscientists,clinicians,publichealthexperts,andcaregivers,wehavesofarbeenabletoanswerthechallengesposedbyaspectrumofpathogensrangingfrom“A”vianinfluenzavirusto“Z”ikavirus.Eachhastakentimeandasomewhattailoredapproach.Wecanexpectsternertestsinthefuture,andsomeofthelessonslearnedmustbecarriedforward.Sincethespreadof(re-)emergingvirusesisnotconfinedbygeographicboundaries,itisclearthatcollaborativesolutionsacrossnationsareneededtosolvetheseglobalproblems.Effortsinthisveinaregettingofftheground.Internationalpartnerships,suchastheGlobalViromeProject(Carrolletal.,2018)forvirushuntingworldwideandtheestablishmentofaCDCnetworkinAfricawithassistancefromtheUSCDCandChinaCDC,willgreatlyimproveourcapacityforsurveillance,contributingto,ideally,aworldwidesysteminthe“bigdata”eraofthe21stcentury.ThePandemicEmergencyFinancingFacility(PEF),launchedbytheWorldBankincollaborationwiththeWorldHealthOrganizationandthegovernmentsofJapanandGermany,aimstoprovideover$500milliontocoverdevelopingcountriesagainsttheriskofoutbreaks.TheCoalitionforEpidemicPreparednessInnovations(CEPI),foundedbytheNorwaygovernment,theBill&MelindaGatesFoundation,theWellcomeTrust,andtheWorldEconomicForumaimtoprovideacoordinated,bench-to-bedsideapproachfor(pre-)clinicalvaccinedevelopmentanddelivery.Theaboveexamplesshowthatwearebeginningtolearnourlessons,butwemustnotforgetthatbasicscientificresearchintobothhigh-profileandobscurepathogensformsacrucialbasisfortheeffectiveimplementationofinformedpublichealthpoliciesandinnovativecollaborativeinitiatives.Robustinvestmentintobasicresearch(i.e.,viralpathogenesis,interspeciestransmission,etc.)shouldbeencouragedtoachieveafullymulti-facetedapproachtocombatingfuturepandemics.
Acknowledgments
WorkinG.F.G.’slaboratoryispartysupportedbytheStrategicPriorityResearchProgramoftheChineseAcademyofSciences(grantno.XDPB03)andtheNationalNaturalScienceFoundationofChina(NSFC,grantno.81621091).MythanksgotoDrs.HaoSongandLianpanDaifortheirhelpofpreparingthefiguresandDrs.GaryWong,DayanWang,TaoChen,YuhaiBi,WilliamJ.Liu,YiShi,andZhongjieLifordiscussions.