Novel influenza A(H1N1) 2009 in vitro reassortant viruses with oseltamivir resistance.
BACKGROUND
With the recent emergence of the novel A(H1N1) virus in 2009, the efficacy of available drugs, such as neuraminidase (NA) inhibitors, is of great concern for good patient care. Influenza viruses are known to be able to acquire resistance. In 2007, A(H1N1) viruses related to A/Brisbane/59/2007 (H1N1) (A[H1N1] Brisbane-like virus), which are naturally resistant to oseltamivir, emerged. Resistance to oseltamivir can be acquired either by spontaneous mutation in the NA (H275Y in N1), or by reassortment with a mutated NA. It is therefore crucial to determine the risk of pandemic A(H1N1) 2009 virus acquiring resistance against oseltamivir by reassortment.


METHODS
We estimated the capacity of reassortment between the A(H1N1) 2009 virus and an oseltamivir-resistant A(H1N1) Brisbane-like virus by in vitro coinfections of influenza-permissive cells. The screening and the analysis of reassortant viruses was performed by specific reverse transcriptase PCRs and by sequencing.


RESULTS
Out of 50 analysed reassortant viruses, two harboured the haemagglutinin (HA) segment from the pandemic A(H1N1) 2009 virus and the mutated NA originated from the A(H1N1) Brisbane-like virus. The replicating capacities of these viruses were measured, showing no difference as compared to the two parental strains, suggesting that acquisition of the mutated NA segment did not impair viral fitness in vitro.


CONCLUSIONS
Our results suggest that the novel A(H1N1) 2009 virus can acquire by in vitro genetic reassortment the H275Y mutated NA segment conferring resistance to oseltamivir.
Ottmann
Michèle
M
Université de Lyon, France. michele.ottmann@univ-lyon1.fr
Duchamp
Maude Bouscambert
MB
Casalegno
Jean-Sébastien
JS
Frobert
Emilie
E
Moulès
Vincent
V
Ferraris
Olivier
O
Valette
Martine
M
Escuret
Vanessa
V
Lina
Bruno
B
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D004285:Dogs; D024882:Drug Resistance, Viral; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D009439:Neuraminidase / Q000235:genetics; D053139:Oseltamivir / Q000494:pharmacology*; D016865:Reassortant Viruses / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D014779:Virus Replication
D000998:Antiviral Agents; D053139:Oseltamivir; D009439:Neuraminidase