Genetic analysis of neuraminidase gene of influenza A(H1N1)pdm09 virus circulating in Southwest India from 2009 to 2012

Genetic analysis of neuraminidase gene sequences in 23 archived isolates of influenza A(H1N1)pdm09 virus, isolated during the 2009–2012 influenza seasons, was carried out to determine the genetic variability. Amino acid substitutions were observed at the rates of 0.3–0.7% per year. The catalytic site consisting of 8 functional and 11 framework residues were found conserved in 20 isolates and mutated in three (E228G, E278G, and N295T) isolates. To the best of our knowledge the three catalytic site mutants observed in our study have not been reported elsewhere to date. Similarly, mutations in the antigenic sites (K217E, K254E, V267A, and D451E except I263V) are discussed for the first time through this article. The effect of these mutations on drug and antibody binding were analyzed using biochemical and structural studies. Detailed studies on the neuraminidase gene are sparse and our study may serve as an appropriate platform to gain insights about the evolution of influenza virus, thereby facilitating drugs/vaccines design and development. J. Med. Virol. 89:202–212, 2017.