Genetic And Evolutionary Analysis Of H1N1 Influenza Virus In Guangzhou In 2016

Influenza a has a history of causing serious epidemics,including the Spanish flu of 1918,the human flu in the United States of America in 1976,the human-animal flu pandemic of 1988,the 2009 influenza pandemic and the 2015 flu.The characteristic of viral subtypes is that they mutate into strains with different pathogen spectra,and finally achieve high adaptability in a short time.Virus surface glycoproteins,HA and neuraminidase(NA)are the most rapidly evolving of all influenza proteins.The amino acid substitution accumulated in the mutant virus allows the virus to evade the immune system.The accumulation of amino acid substitutions in mutant viruses enables the virus to evade the immune system.This accumulation process of amino acid substitutions can lead to antigen changes of surface glycoproteins,namely antigen drift.The accumulation of amimo acid substitutions in mutant viruses enables the virus to evade the immune system.This accumulation process of amimo acid substitutions can lead to antigen changes of surface glycoproteins,namely,antigen drift or point mutations.In addition to point mutations,gene recombination plays an important role in the evolution of emerging viruses.This project intends to obtain the genome information of 2016 guangzhou influenza virus through sequencing,so as to understand the variation and genetic evolution of HlNlpdm virus in guangzhou,and provide data support for the follow-up experimental research of type A(H1N1)influenza in guangzhou and the prevention and control of influenza pandemic.Objective:The 15 strains of influenza virus in guangzhou in 2016 were isolated,their genetic sequencing was performed to analyze their varnation,and evolutionary analysis and selection pressure analysis were performed to provide scientific basis for follow-up virus research,understanding virus resistance and causing,and searching for variation rules.Methods:Viruses extracted from patients with pharyngeal swab and rt-pcr method for virus identification,application of the second generation sequencing technology was developed for the determination of 15 isolates whole genome sequence,through MAGA6.0 softvware and reference strains pdm2009(A/California/07/2009(H1N1))compare,analysis of amino acid variation,and phylogenetic analysis and stress analysis,to reveal the 2016 guangzhou HINlpdm virus pattern of change.Results:15 isolates of H1N influenza virus were compared with the reference strain pdm2009(A/Califormia/07/2009(H1N1)),and it was found that the variation of 8 protein fragments was not high,and no variation of HA protein receptor binding site was found.No variation of NA protein was found in amino acid sites related to drug resistance,indicating sensitivity to neuraminidase inhibitors.No variation related to antigenicity,ability of virus to infect cells and replication and transcription of virus genome was found.Phylogenetic tree analysis showed that with HA gene as the target gene,the virus strains isolated in this study were independent of 7 branches of H1N1pdm virus circulating in the world.In the process of virus evolution,two lineages were formed and there was no recombination between them.Selection pressure analysis showed that there were 6 positive selection sites in the main surface proteins of H1N1pdm virus.Conclusion:Mild infection caused by H1N1 influenza virus in guangzhou in 2016.The epitopes of virus antigens did not change,no new drug-resistant strains appeared,and no virulent strains were found.With HA gene as the target gene,the virus strains isolated in this study were independent of 7 branches of H1N1pdm virus circulating in the world.In the process of virus evolution,two lineages were formed and there was no recombination between them.The 6 protein sites of HINlpdm virus experienced positive selection in the process of virms evolution.The HINlpdm virus in guangzhou is constantly evolving,so it is necessary to continuously monitor the H1N1pdm virus to prevent its epidemic.