Study On Genomic Variability Of Influenza A H1N1 Virus

For a long time,the flu has been plaguing people.Influenza A virus,a highly variant of the virus,has been spread on a large scale worldwide since 1876.The outbreak of H1N1 influenza a worldwide in 2009 has caused great trauma to all aspects of human life and property.So,the study of the variant characteristics of influenza virus is particularly important for the formulation of influenza prevention and control measures.The variation rules of 10 protein sequences of 8 genomic segments of human influenza A virus H1N1 from 2007 to 2011 were analyzed.Based on the definition and visualization of variation parameters,we explored the variation of amino acids in the genome sequence of influenza virus before and after the outbreak of influenza virus.The main research of this thesis include:(1)This paper is mainly about the 10 full length protein sequences of PB1,PB2,PA,HA,NP,NA,M and NS of 8 genomic segments of human influenza A virus H1N1 from 2007 to 2011.The 10 full length protein sequences are PB1,PB2,HA,NP,NA,M1,M2,H2,and NS1,NS2.First,we use the frequency of amino acids in each sequence to uniquely represent the corresponding protein sequences,and get a set of digitalized mapping matrix of protein sequences.Then,the matrix after PCA dimensionality reduction is clustered using the K-means++ clustering method,and the subgroups after the sequence clustering are obtained.(2)The relative deviation of the protein sequence and the analysis method of mutation activity were defined,and the variation of influenza virus in the transmission process was studied.Relative migration refers to the mean number of amino acid substitutions in the same period of the virus relative to the vaccine strains provided by WHO,while the mutation activity indicates the mean value of the newly increased amino acid substitutions of the virus in the same period compared to the WHO vaccine strains.(3)Through the visual analysis of the relative degree of deviation and the degree of mutation activity,it was found that during the period before and after the outbreak of influenza virus,these two parameters showed a sharp increase from the first to the sudden outbreak of influenza,and then slowly increased with time.The trend from which to verify that the investigation of these two parameters can alert the spread of influenza virus.