2017—2018年重庆口岸甲型H1N1流感病毒分离株基因变异分析

Analysis of gene variation of influenza A(H1N1)virus isolated in Chongqing port from 2017 to 2018

目的研究重庆口岸甲型H1N1流感病毒分离株血凝素(HA)及神经氨酸酶(NA)基因特征,为口岸输入性甲型H1N1流感病毒的溯源和防控提供依据。方法对2017—2018年重庆口岸入境发热人群呼吸道样本进行甲型H1N1流感病毒分离培养,选取不同时间和地点15个病毒株进行HA、NA基因片段RT-PCR扩增及序列测定,并进行核苷酸及氨基酸序列分析。结果进化分析显示,2017—2018年的重庆口岸甲型H1N1流感病毒分离株与疫苗株进化关系均较近,相对于其他地区,与重庆本地毒株进化关系较远。15个分离株的HA基因核苷酸与疫苗株A/Michigan/45/2015(H1N1)同源性为98.4%~99.1%,氨基酸同源性为98.1%~99.8%;NA基因核苷酸同源性为98.4%~99.7%,氨基酸同源性为98.3%~99.8%。15个分离株的HA基因分别在cb区和Sa区存在重要位点氨基酸变异;毒株SWL225在NA基因的氨基酸出现H275Y变异,提示此毒株为达菲耐药株。结论重庆口岸甲型H1N1病毒的HA、NA序列与疫苗株同源性较高,但存在耐药株输入危险。

Objective To study the gene characteristics of hemagglutin(HA)and neuraminidase(NA)gene of influenza A(H1N1)virus at Chongqing port.Methods The respiratory samples of entry passengers with fever in Chongqing port were isolated for influenza A(H1N1)virus.Fifteen H1N1 influenza virus strains were chosen according to the different time and places of isolation.HA and NA gene fragment were amplified by RT-PCR and sequenced,and then the sequences of nucleic and amino acid were analyzed.Results Phylogenetic analysis indicated that the relationship between H1N1 viruses from 2017 to 2018 and the vaccine strain was close to each other.Compared with the vaccine strain A/Michigan/45/2015(H1N1),the homologies in nucleotide and amino acid sequences for HA gene were 98.4%-99.1%and 98.1%-99.8%,for NA gene were 98.4%-99.7%and 98.3%-99.8%,respectively.The HA gene of 15 isolates had amino acid mutations at important sites in the cb and Sa region,respectively.The strain SWL225 had H275Y mutations in the amino acid of the NA gene,suggested that the strain was a Duffy-resistant strain.Conclusion The HA and NA sequences of influenza A(H1N1)virus in Chongqing port were highly homologous epidemic to the vaccine strains.There was potential imported risk of drug-resistant strains.Influenza A(H1N1)virus in Chongqing are still sensitive to Duffy.