Neuraminidase H275Y and hemagglutinin D222G mutations in a fatal case of 2009 pandemic influenza A (H1N1) virus infection.

Oseltamivir-resistant 2009 H1N1 influenza virus infections associated with neuraminidase (NA) H275Y have been identified sporadically. Strains possessing the hemagglutinin (HA) D222G mutation have been detected in small numbers of fatal 2009 H1N1 cases. We report the first clinical description of 2009 H1N1 virus infection with both NA-H275Y and HA-D222G mutations detected by pyrosequencing of bronchioalveolar lavage fluid obtained on symptom day 19. The 59-year-old immunosuppressed patient had multiple conditions conferring higher risk of prolonged viral replication and severe illness and died on symptom day 34. Further investigations are needed to determine the significance of infection with strains possessing NA-H275Y and HA-D222G.