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The New Influenza A/H1N1 Isabelle Thomas May 28-29, 2009 Brussels. ,. HA. SCIENCE VOL 324 15 MAY 2009. Influenza virus . Famille Orthomyxoviridae …… . Genus Influenza (80-100 nm) 8 RNA segments 2 Surface glycoproteins (HA, NA) 3 Types (A, B, C) - PowerPoint PPT Presentation
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The New Influenza A/H1N1
Isabelle Thomas May 28-29, 2009 Brussels
,
HA
SCIENCE VOL 324 15 MAY 2009
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 Aall subtypes, 16H, 9N
Swine : Type AH1N1, H3N2 , H1N2, ……
HA
NA
Reassortant
Human Pandemic influenza viruses: reassortment is postulated to have occurred in pigs
Influenza Viruses: Continuous evolutionAntigenic “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/192/07A/Belgium/198/07A/Belgium/189/-07A/Belgium/209/-07A/Belgium/203/07A/Belgium/194/07A/Belgium/146/-07A/Belgium/124/07A/Belgium/122/07
A/Belgium/945/-07A/Belgium/953/-07
A/Belgium/917/-07A/Belgium/946/07A/Belgium/963/07
A/Belgium96/07A/Belgium/139/07A/Belgium/141/07A/Belgium/140/07
A/Belgium/144/07A/Belgium/919/07A/Belgium/959/-07A/Belgium/114/07A/Belgium/916/-07A/Belgium/930/07A/Belgium/931/-07
A/Belgium/206/07
A/Wisconsin/67/ 2005 A/California/7/2004
A/Fujian/ 411/ 2002 A/Wyoming/3/ 2003
H3N2
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
Surveillance National : National Influenza Centers (NIC) European : EISS, ECDC International : WHO
ObjectivesTo monitor influenza activityTo determine types and subtypes of the circulating strainsTo characterize circulating strains (Antigenic and Genetic
characterization)To contribute to the annual determination of the influenza vaccine
contentTo monitor resistance to antiviralsTo be able to detect any new human influenza virus : ex A/H7N7,
A/H5N1,
Surveillance of Influenza viruses :
WHO Alert : 26 AprilNew virus A/H1N1 of swine origin
Cases in Mexico Cases in USA
Characteristics Typable Real time PCR AUnsubtypable Real time PCR H1 seasonal
Sequences of new strains rapidly availableDevelopment of real time PCR specific for SWH1N1
Surveillance of Influenza viruses :
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 originPA & PB2 from avian originNP & NS from American swine
H5N1
New H1N1
• 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, SWA150 suspected cases8 positive swH1N1 cases 5 patients coming back from the USA3 close contact from one of the patients
Current situation
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
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