| Objective:To investigate the epidemiological characteristics and genomic sequences of human infections with influenza A(H1N1)virus in Zhejiang province from 2013 to 2015,and explore the viral molecular characteristic.Methods:Epidemiology and clinical surveys were conducted for acute respiratory infection(ARI)cases monitored by eight sentinel hospitals in Zhejiang province from 2013 to 2015,and their respiratory tract specimens were collected for influenza virus detection.The cases were classified into two groups by influenza A(H1N1)virus,and analyzed their clinical and epidemiologic characteristics.15 positive specimens with influenza A(H1N1)virus infection were randomly selected and amplified by RT-PCR.Then the genes were equenced,spliced out the genome sequence by DNAstar.HA and NA sequences of influenza A(H1N1)virus in China were collected from GenBank or GISAID,Genetic and phylogenetic analyses were performed by MEGA6.0 software.Compared with the vaccine strain,analyzed the change of the key amino acid site.The DNAStar software was applied to forecast the haemagglutinin and neuraminidase protein of B lymphocyte antigen epitope.Results:1.7602 severe acute respiratory infection cases were recruited from eight hospitals,including 779(10.2%)cases of laboratory confirmed influenza A(H1N1)in Zhejiang province from 2013 to 2015.Influenza A(H1N1)cases usually occurred in winter and spring in Zhejiang province,and at least Between May and August of each year,other times appear sporadic.The incidence of influenza A(H1N1)in patients with chronic lung disease and pregnant women were higher than that in negative cases,the difference was statistically significant.2.The total number of white blood cells showed normal or decreased,C reaction protein increased.In most cases,Aspartate aminotransferase,Aanine aminotransferase,Lactate dehydrogenase,Creatine kinase,Creatinine and Procalcitonin was in the normal range;X-ray/CT showed abnormal(81.7%)or lung auscultation showed abnormal(76.0%).3.Phylogenetic analysis indicated that these genes of 15 representative strains in Zhejiang province from 2013 to 2015 were homology high to 96.5%～98.7%with the WHO recommended vaccine strain A/Califomia/07/2009(H1N1);The homogeneity of nucleotide of 15 representative strains in Zhejiang province were 97.4%～100%.4.Compared with the vaccine strain,there were 5 amino acid sites(83,185,203,321,374)mutations in 15 representative strains of the HA protein.There were 6 amino acid sites(44,200,241 248,351,369)mutations in 15 representative strains of the NA protein.5.The key amino acid sites analysis showed that HA protein of 3 representative strains had Q223R receptor binding site mutation.There was 1 strain with H275Y,V241I and N369K mutation in NA protein at the same time.M2 protein of 15 representative strains and vaccine strains had S31N mutation in drug resistance sites;PB1 protein of 1 strain with G87E mutation.PA protein of 15 strains had V100I mutation.NS1 protein of 15 representative strains and vaccine strains had P42S,V149A mutation.6.Compared with vaccine strains,there were HA protein of 5 strains increased glycosylation sites in 162,there were NA protein of 5 strains increased glycosylation sites in 42,NA protein of 1 strain increased glycosylation sites in 381,as well as original glycosylation sites of the other strains missing.7.The DNAStar software was applied to forecast HA and NA protein,which B cell surface antigen epitope section in HA protein were:50-55,139-144,172-176,185-189,221-226,372-377,473-480,504-508,and B cell surface antigen epitope sectiorrin NA protein were:1-9,60-64,103-109,154-160,215-220,273-280,320-338,423-431.Conclusions:1.Outbreaks of influenza A(H1N1)cases usually occurred in winter and spring in Zhejiang province,and at least Between May and August of each year,other times appear sporadic.2.Influenza A(H1N1)virus HA protein had mutations in key amino acid sites(such as D222G,etc.),which may be closely related to the spread of the virus across species.3.The key amino acid site analysis of each gene showed mutations in some sites,which may be associated with increased virus toxicity and the virus epidemic.4.Influenza A(H1N1)virus strains in Zhejiang province are resistant to ion channel inhibitors(amantadine,rimantadine),but also found oseltamivir resistance(NA protein H275Y mutation)virus strains. |
