Evolution and phylodynamics of Hemagglutinin protein of Influenza A/(H1N1)pdm09 virus isolates from India during 2009 to 2020.

Influenza A/(H1N1)pdm09 virus evolves through continuous antigenic variation in both surface antigens such as hemagglutinin (HA) and neuraminidase (NA) proteins impacting pathogenicity, immune effectiveness and drug resistance. This study reports on evolution and dynamics of 527 HA protein sequences of influenza A/(H1N1)pdm09 Indian isolates submitted between the years 2009-2020. These isolates were aligned along with a reference sequence and 22 sequences representing different clades using MEGA X and subjected to phylogenic analyses. The results revealed that the strains were predominantly grouped in clades 6B.1 and 6B.2. Prediction of glycosylation site using BioEdit and NetNglyc server showed twelve glycosylation sites distributed in both stem and globular head regions of HA. Studies on functional evaluation of mutations showed that there were 22 deleterious mutations that could impact the function of HA. Besides, there were 403 unique mutations distributed across various isolates indicating the dynamics of antigenic variation in Indian isolates. Our analysis will help researchers to understand the frequency, phylodynamics and impact of mutations in Indian isolates of Influenza A/(H1N1)pdm09 with respect to global isolates. Monitoring of genomic evolution of the virus will support studies on strain selection for vaccine development and devising control and preventive measures to manage this respiratory infection.