禽流感病毒的演變與傳播 Evolution,Adaptation and Spread of Influenza Viruses課件

1、Evolution, Adaptation and Spread of Influenza Viruses: What Have We Learned?Nancy J. Cox, Ph.D.Chief, Influenza BranchNational Center for Infectious DiseasesCenters for Disease Control and PreventionInfluenza Historical BackgroundEpidemics of influenza have occurred in humans since ancient times rec

2、orded by Hippocrates in 412 BC“Influenza” term dates from 15th century Italy when epidemics were attributed to the influence of the starsFirst pandemic clearly described in 1580Background, continuedInfluenza A virus isolated in ferrets in 1933 by Smith et al.Virus first grown in embryonated eggs in

3、1936Antigenic differences detected between viruses in 1937Influenza B virus isolated in 1940 by Francis and McGill (independently)Inactivated influenza vaccine found to be effective in 1944 (U.S. military)Influenza VirusesEnveloped RNA viruses, 80-100 nm in diameter 8 single-stranded negative sense

4、gene segments encoding 10 proteinsAerosol and droplet transmissionIncubation period 1-4 daysViral sheddingAdults B virusesAntigenic “shift” occurs in HA and NAAssociated with pandemics Appearance of novel influenza A viruses bearing new HA or HA & NAInfection and DiseaseHighest infection & disease r

5、ates in childrenHighest rates of serious complications in elderly and persons with certain underlying chronic conditions, e.g.:Cardiopulmonary diseaseMetabolic disease (e.g. diabetes)Immune deficiencyHuman virusReassortantvirusNon-humanvirusPost-1997 View of Transmission of Avian Influenza A Viruses

6、 to Humans15 HAs9 NAsDIRECTPandemics and Pandemic “Scares”of the 20th Century1918-19 “Spanish flu”H1N11957 “Asian flu” H2N21968 “Hong Kong flu”H3N21976 “swine flu” episodeH1N11977 “Russian flu”H1N11997 “Bird flu” in HKH5N11999 “Bird flu” in HKH9N21957-58 and 1968-69 Pandemics1957Emergence of influen

7、za A (H2N2) virus66,000 U.S. deaths36% of deaths (24,000) in persons 65 years1968Emergence of influenza A (H3N2) virus28,100 U.S. deaths41% of deaths (11,600) in persons 20,000 deaths110,000 hospitalizationsCurrently 90% deaths in persons 65 yearsHigher numbers of deaths and hospitalizations in A(H3

8、N2) yearsP&I Mortality for 122 U.S. Cities& Associated Influenza Viruses91-9292-9393-9494-9595-9696-9797-9898-9999-0000-0101-02A(H3N2)A(H1N1)BSeasonal Occurrence of Influenza Tropical (Singapore and S. China) Temperate-N. Hemisphere (Japan and U.S. West Coast) Temperate-S. Hemisphere (Australia)00.2

9、1Relative Influenza ActivityJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECWHO Recommendations for Vaccine StrainsFormal recommendations for strains to be included in the currently licensed inactivated influenza vaccine are made each year during February for the following influenza season in the North

10、ern Hemisphere and in September (since 1998) for the following season in the Southern Hemisphere.Considerations for RecommendationsAre there new antigenic variants (HI and gene sequencing data)?Are new variants spreading and causing disease?Are current vaccines able to induce antibodies to the new v

11、ariants?Are any new variants useful for vaccine production?Why Sequence HA Genes?Sequence analysis provides information on the molecular basis for antigenic drift.Sequence analysis provides precise data onevolutionary relationships between HA genes ofInfluenza viruses.Sequence data provide adjunct t

12、o HI data for vaccine strain selection. Rates of change at nucleotide/amino acid levelsTypes of amino acid changesPositions of amino acid changesPredictability in patterns of changeMolecular correlates with epidemiologyPanama/2007/99Moscow/10/99Sydney/5/97Johannesburg/33/94Beijing/32/92Beijing/353/8

13、9Sichuan/11/87Mississippi/1/85Philippines/2/82Bangkok/1/79Nanchang/933/95H3 HAConclusions fromPrediction AttemptsWe identified 18 codons in HA1 that are positively selected; sites A, B and RBPStrains with more mutations in these codons = progenitors of successful new lineages retrospective testingAl

14、ternate hypotheses less successful in predictingMonitoring change in + selected codons may predict course of evolution and be useful for vaccine strain selectionSignature Amino Acid Changes Observed Between the HAs of A/Johannesburg/33/94 and A/Nanchang/933/95-like VirusesJoh/33/94Nan/933/95G135T, N

15、145K, N262S 135135135145145145262ABCDEModel of the Influenza A H3 HA StructureTop viewSide viewApproachGenerate transfectant viruses with the Joh/HA containingsingle mutations alone G135TN145KN262S and combinations of double mutations G135T/ N145K G135T/ N262SN145K/ N262SDetermine antigenicity of ea

16、ch mutant virus using post-infection ferret sera in an HI assayvRNA expressing plasmidsPAPB1PB2NPNAMNSNPPB2PB1PAPR8 protein expression plasmidsPlasmid-based Reverse GeneticsPR8wt or mutant Joh/94Joh/94HA293T cellSummary of Reverse Genetics ExperimentsThe presence of each mutation alone was insuffici

17、ent to recreate the antigenic difference observed between Johannesburg/33/94 and Nanchang/933/95-like viruses.But, the combination of mutations G135T and N145K in site A of the Joh 94 HA were sufficient to re-create this example of antigenic drift in the H3 HA. Reverse genetics techniques allowed us

18、 to identify contribution of specific aa residues to antigenic drift in the H3 HA. Look at other examples and at contributions of 18 codons.The Flu Brew: Is it Right?Organization of WHOs Influenza ProgramNational Influenza Centers(Approx. 110 Labs in 80 Countries)World Health Organization(Geneva)Vac

19、cine ProducersInternational Collaborating Centers (Atlanta, London, Melbourne, Tokyo)Isolate influenza virusesIdentify viruses and send toInternational Collaborating Center(s)Collect epi informationCollect information for the WeeklyEpidemiological Record and WWW for distributionMake annual vaccine r

20、ecommendationsAnalyze influenza viruses Provide data for vaccine recommendations Distribute vaccine virusesCurrent Status of WHO System175,000 isolates/yr (600 to 1200 M cases)WHO CCs receive 6,500 samples/yr.WHO CCs and NICs sequence 1,000 samples/yr.240 M doses of influenza vaccine produced worldw

21、ideEnhancing Surveillance for Pandemic and Epidemic InfluenzaNeed higher throughput labs Need better data collectionLab + Epi linkedNew algorithms for identifying key virusesIncrease data based size for better predictive methodsMatch Between Epidemic and VaccineStrains of Influenza, USA, 1992-2001+

22、identical or minimal difference + substantial cross-reactionSeasonEpidemic Strain(s)Vaccine Strain(s)Antigenic MatchA/Shangdong/09/93 (H3N2)A/Shangdong/09/93 (H3N2)1995/961996/971997/98A/Texas/36/91 (H1N1)A/Texas/36/91 (H1N1)A/Johannesburg/33/94 (H3N2)A/Nanchang/933/95 (H3N2)A/Sydney/5/97 (H3N2)A/Na

23、nchang/933/95 (H3N2)A/Nanchang/933/95 (H3N2)A/Johannesburg/33/94 (H3N2)+ moderate cross-reaction + some cross-reaction1998/99A/Sydney/5/97 (H3N2)A/Sydney/5/97 (H3N2)1999/00A/Sydney/5/97 (H3N2)A/Sydney/5/97 (H3N2)2000/01A/New Caledonia/20/99 (H1N1)B/Sichuan/379/99A/New Caledonia/20/99 (H1N1)B/Yamamas

24、hi/166/98+2001/02A/Panama/20/07 (H3N2)A/Panama/2007/99 (H3N2)Factors Contributing to ImprovedInfluenza Vaccine Match Better Worldwide SurveillanceEurope, Latin America and AsiaImproved CommunicationsTelephone and FaxE-mailTechnical AdvancesMolecular AnalysesIncreasing International CooperationExchan

25、ge of Viruses and Serum PanelsStandardization of Reagents and VaccinesSuccess of WHOsInfluenza Surveillance NetworkAction-orientated networkReagents updated annuallyAnnual recommendationsCollaborative spirit of participantsof Influenza B VirusPeriods of Observed Circulation in Humans20011940BB/Victo

26、ria/2/87-like1987B/Yamagata/16/88-likeGenetic Reassortment in Influenza VirusesHemagglutination Inhibition Reactions of Influenza B Viruses of the Yamagata and Victoria LineagesStrain designationFerret antisera Sic/379Shi/15Joh/69BJ/243HK/22HK/330B/Sichuan/379/996401280320201020B/Shizuoka/15/2001320

27、1280640101010B/Johanessb./69/20013201280320101010B/Beijing/243/972010103201601280B/Hong Kong/22/2001101010160640640B/Hong Kong/330/2001101010160160640B/Taiwan/97271/2001160640320101010B/New York/47/2001320640320101010B/Texas/3/20026401280320102010B/Oman/16296/2001102010160160320B/Philippines/5072/20

28、011010104080160B/Malaysia/83077/20011010108080160B/India/7600/20012010108080160B/Hong Kong/1351/20021010 40 PreVaccine PostVaccineUK24B/Sichuan/379/99* ET969293810024B/Brazil/956/2001 ET96163702510024B/Shizouka/15/2001 ET96103021710024B/Hong Kong/330/2001 ET7164847124B/Hawaii/10/2001 ET75642467Austr

29、alia24B/Sichuan/379/99* ET100192263810024B/Brazil/956/2001 ET100213024210024B/Shizouka/15/2001 ET96183293810024B/Hong Kong/330/2001 ET4682484624B/Hawaii/10/2001 ET42822846CanadaSwitzerlandIsraelOmanIndiaThailandHong KongChinaJapanPhilippinesHawaiiGeographic Distribution of B/Victoria/02/87 Lineage VirusesApril 2001 to PresentUSAItalyNetherlandsAustraliaConclusionsInfluenza B/Victoria/2/87 lineage viruses have reemerged in North America and Europe after a 10 year absence. Reassortment has occurred between 2 lineages of B viruses.Genetic