1. The New Influenza A/H1N1 Isabelle Thomas May 28-29, 2009 Brussels,

2. HA SCIENCE VOL 324 15 MAY 2009

3. Influenza virus Famille Orthomyxoviridae ……. Genus Influenza (80-100 nm) 8 RNA segments 2 Surface glycoproteins (HA, NA) 3 Types (A, B, C) Human : type A and B H1N1, H3N2, B,… Wild bird: type A all subtypes, 16H, 9N Swine : Type A H1N1, H3N2, H1N2, …… HA NA

4. Reassortant Human Pandemic influenza viruses: reassortment is postulated to have occurred in pigs

5. Influenza Viruses: Continuous evolution Antigenic “drift”: Point mutations in the hemagglutinin gene cause minor antigenic changes to HA. Antigenic “drift” causes seasonal epidemics Nucleotide Substitutions (x100) 0 2.8 2 A/Belgium/192/07 A/Belgium/198/07 A/Belgium/189/-07 A/Belgium/209/-07 A/Belgium/203/07 A/Belgium/194/07 A/Belgium/146/-07 A/Belgium/124/07 A/Belgium/122/07 A/Belgium/945/-07 A/Belgium/953/-07 A/Belgium/917/-07 A/Belgium/946/07 A/Belgium/963/07 A/Belgium96/07 A/Belgium/139/07 A/Belgium/141/07 A/Belgium/140/07 A/Belgium/144/07 A/Belgium/919/07 A/Belgium/959/-07 A/Belgium/114/07 A/Belgium/916/-07 A/Belgium/930/07 A/Belgium/931/-07 A/Belgium/206/07 A/Wisconsin/67/ 2005 A/California/7/2004 A/Fujian/ 411/ 2002 A/Wyoming/3/ 2003 H3N2

6. Influenza viruses : Continuous evolution Antigenic “shift”: Emergence of a new human influenza A virus subtype (new HA subtype +/- NA). Little or no immunity pandemic risk

7. Surveillance  National : National Influenza Centers (NIC)  European : EISS, ECDC  International : WHO Objectives To monitor influenza activity To determine types and subtypes of the circulating strains To characterize circulating strains (Antigenic and Genetic characterization) To contribute to the annual determination of the influenza vaccine content To monitor resistance to antivirals To be able to detect any new human influenza virus : ex A/H7N7, A/H5N1, Surveillance of Influenza viruses :

8. WHO Alert : 26 April New virus A/H1N1 of swine origin Cases in Mexico Cases in USA Characteristics Typable Real time PCR A Unsubtypable Real time PCR H1 seasonal Sequences of new strains rapidly available Development of real time PCR specific for SWH1N1 Surveillance of Influenza viruses :

9. Comparison of H1N1 Swine Genotypes in Recent Cases in the United States Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. N Engl J Med 2009;10.1056/NEJMoa0903810 H1 from American swine (>6% divergent) N1 & M from Eurasian swine PB1 from human origin PA & PB2 from avian origin NP & NS from American swine

10. H5N1 New H1N1

11. More than 8000 confirmed cases in 40 countries 74 reported death Most cases seem to be mild and self-limited The virus is transmitted easily from person-to-person Countries have rapidly developed important diagnostic capacity In Belgium Real Time PCR A, SWH1, SWA 150 suspected cases 8 positive swH1N1 cases 5 patients coming back from the USA 3 close contact from one of the patients Current situation

12. With Influenza viruses nothing can be predicted How Fast will the virus spread throughout the world? Will it become widely established? Will the infectivity and virulence of the virus change over time? Evolution

13. Acknowledgments Virology C. Gérard Ch. Van den Poel M. Abady I. Fdillate I. Micalessi B. Brochier D. Bauwens Y. Ronflette Epidemiology S.Quoilin F.Wuillaume