In this
paper, we analysed the haemagglutinin (HA)
gene identified by
polymerase chain reaction from 90 influenza A
H1N1 virus strains that circulated in
Brazil from April 2009-June 2010. A
World Health Organization sequencing protocol allowed us to identify
amino acid mutations in the HA
protein at positions S220T (71 percent), D239G/N/S (20 percent), Y247H (4.5 percent), E252K (3.3 percent), M274V (2.2 percent), Q310H (26.7 percent) and E391K (12 percent). A
fatal outcome was associated with the D239G
mutation (p < 0.0001). Brazilian HA
genetic diversity, in comparison to a reference
strain from
California, highlights the
role of
influenza virus surveillance for study of viral evolution, in addition to
monitoring the spread of the
virus worldwide.