Similarity of currently circulating H1N1 virus with the 2009 pandemic clone: Viability of an imminent pandemic

•We predict the increased potential for a second wave of H1N1pdm09 in near future.•Amino acid usage pattern of hemagglutinin (HA) genes can envisage the severity in disease outbreak.•Currently circulating H1N1 is evolutionary different from the H1N1pdm09 due to the accumulation of mutations in HA protein.•HA sequence from the year 2014 contains a unique mutation in the epitopic region Sa.

The first influenza pandemic in the 21st century commenced in March, 2009 causing nearly 300,000 deaths globally within the first year of the pandemic. In late 2013 and in early 2014, there was gradual increase in the reported case of H1N1 infection and according to World Health Organization (WHO) report, influenza activity increased in several areas of the Southern Hemisphere and was dominated by the H1N1 pandemic strain of 2009. In the present study, a comprehensive comparison of the global amino acid composition and the structural features of all HA gene sequences of H1N1, available in the Flu Database (NCBI), from 1918 to December, 2014 has been performed to trace out the possibility of a further H1N1 pandemic in near future. The results suggest that the increased potential to enhance pathogenicity for the H1N1 samples of 2013 (latter part) and 2014 could lead to a more severe outbreak in the near future.