Recent mutations in NS1 protein of H1N1 influenza virus isolated from
India during 2009 to 2019
Abstract
The routine influenza (H1N1) surveillance in India started almost a
decade ago. The fluctuation in the number of deaths and cases in
different Indian states over the last decade presumably indicated the
possible changes in the viral sequence and in the immune response of the
host. To track these changes, we have chosen NS1 protein that invades
host antiviral immune response. Objective of this study was to identify
the recent mutations on NS1 protein from Indian isolates. The sequences
of NS1 proteins from H1N1 strains isolated in India over a decade were
obtained from publicly available databases. Multiple sequence alignment,
phylogeny and surface hydrophilicity analyses were performed to confirm
the consistent mutations on NS1 protein, evolved chronologically in
India. Total eight mutations were identified, two in RNA-binding domain
(RBD), five in effector domain (ED) and one in the linker region. Three
mutations were reported first time in this study at the sequence
positions, 2, 80 and 155; those evolved either in 2017 or in 2019. These
recent mutations were associated with conservative substitutions in the
alternative domains of NS1 protein, namely, i) D2E and E55D, ii) T80A
and A155T and iii) E55K and K131E. A gradual shift of NS1 antigenic
regions (surface hydrophilicity) was observed from ED to RBD domains
along the time line. The possible consequences of these mutations on
host-pathogen interactions were hypothesized based on the sequence
positions of NS1 mutations belonging to various cellular-binding
sub-domains. The hypothesis is subject to further experimental and
computational verification.