Evidence of the circulation of pandemic influenza (H1N1) 2009 with D222D/G/N/S hemagglutinin polymorphisms during the first wave of the 2009 influenza pandemic.

Background: The hemagglutinin HA1 D222G substitution may be associated with adverse outcomes in pandemic influenza A (H1N1) 2009 infections by enhancing the binding capacity of α2-3 sialyl receptors to pandemic influenza (H1N1) 2009 viruses.

Objectives: To investigate the emergence of the D222G mutation and other polymorphisms at this position during the first southern hemisphere pandemic wave in 2009.

Study Design: A total of 127 samples that were nucleic acid test positive for pandemic influenza (H1N1) 2009 virus were subjected to a sequence-based genotypic assessment of viral populations.