By means of sequence analysis, we demonstrate here that multiple HA subtypes of influenza A virus undergo similar mutation patterns of HA1 protein (the immunogenic part of HA).
The synonymous codon usage pattern analyses indicate that the effective number of codons versus GC content at the third codon position in the HA1 gene slightly differ from those in swine H1N1 and gradually adapted to human.
The present study was planned to understand the genetic diversity (based on the HA1 gene) of influenza A(H1N1)pdm09 strains circulating during the post pandemic period.
A total of 548, 2,123, and 1,336 sequences of the HA1 genes of influenza A virus subtypes H1 and H3 and influenza B virus, respectively, collected during 2003 to 2006 from an island-wide surveillance network were determined.