Evolutionary Pattern Of NS1 Gene Of Human H3N2 Influenza Virus In China

Influenza A virus remains an important pathogen which threatens health of human in long time,China is the main resources of the new variants,and NS1 gene of influenza is the determinant virulence factor. Deeply understanding the evolution and variation rule of NS 1 gene has very important meaning for prevention of influenza.With the help of latest developed data mining technique and phylogenetic analysis method, evolution rule of H3N2/NS1 gene were explored from bioinformatics point of view,the research detail were as follows: 1,Two-step cluster analysisTwo-step cluster was applied to explore the basic rule of sequence evolution.The result shows that all sequence could be split into 4 clusters, host distribution between clusters reflect the inherit distance of different host strain,while time distribution of clusters shows the variation history of H3N2/NS1 gene in human being.2,Phylogenetic tree analysisPhylogenetic tree analysis was applied to study evolution rule of H3N2/NS1 gene in detail.The results were consistent with that of the cluster analysis.Beside provide evolution history detail of NS1 sequence, two importance questions were also answered:First,swine mainly play a role of exchange recipient for old variation strains.Second,as to variation of human influenza virus,China is a early stage for NS1 drift,it should not be concerned as origin of new strain all the time.3,Test for positive selected sitesBased on the trunk of tree structure,codon-substitution model was applied to search positive selected sites.Results shows that immunization pressure on H3N2/NS1 sequences is not constant in different period, likelihood test results indicate that pressure increased with time,and reach the climax after 1990s.Ten amino acids were identified as positive selected sites,while most of them were associated with the adaptive evolution for influenza virus. While answer the question of epidemiology,the research set up the primary method for sequence evolution analysis.Our result indicates the serious methods used in this paper could satisfy the need of related analysis;it is worthwhile to be applied in similar research.