Molecular and Phylogenetic Analysis and Protein Structural modeling of NS Gene of Human Influenza A Virus Subtype H1N1 Circulating in Iran 2015 & 2017

Abstract Background:   The NS (non-structural) genomic segment of influenza A virus expresses two proteins (NS1 and NS2) which are responsible for the virulence and pathogenicity of virus. In this study we investigate the characterization and variability of the NS gene recovered from H1N1 influenza viruses isolated from Iranian patients during the 2017 seasonal outbreak  and from highly pathogenic 2015 outbreak. Materials and methods: Positive specimens with high viral load underwent virus amplification on cell culture. The NS segments were amplified and sequenced from randomly selected samples. Genetic characterization, phylogenetic and protein modeling analysis carried on obtained data reference sequences from other geographic regions available in GenBank using Bioedit, MEGA7 softwares and Muster, Modweb, Modfold, Tm-align web servers.   Result : Phylogenetic analysis on the NS gene of A/H1N1 isolates revealed that all the subjected Iranian isolates except to A/Tehran/SMO08/2015 were close to strains from Continental countries of Asia and North America with 99% identity. Meanwhile the mentioned exception was clustered with some strains from Iran, Kazakhstan, Myanmar, Turkmenistan, Jordan. Overall 6 substitutions were observed through the deduced Iranian NS1 and NS2 amino acid sequences. One of the mutations (the E96D mutation in isolate A / Tehran / A7106 / 2017) was first observed in the present project Prediction of three-dimensional structure of Iranian NS1& NS2 proteins in comparison with counterpart references available in PDB showed a slight deviation in functional domains. Discussion: The high similarity of Iranian NS gene with those from other countries, indicate that no significant changes in molecular features of NS genes. None of the observed mutations implied the severity of symptoms so molecular analysis of other alleles is needed to explain the high pathogenic feature of 2015 isolates.