苏州市H5N6亚型高致病禽流感暴发疫情病毒基因特征分析

Genetic characteristics of highly pathogenic avian influenza A(H5N6) virus in Suzhou City

目的对苏州市H5N6亚型高致病禽流感暴发疫情病毒进行全基因测序,分析病毒基因变异情况。方法实时荧光-逆转录聚合酶链反应(real-time fluorescent quantitative reverse transcription-polymerase chain reaction,RT-PCR)方法检测病死禽咽/肛拭子、疑似病例咽拭子标本甲/乙型及各亚型流感病毒核酸。Sanger法对H5N6病毒进行全基因测序并构建HA及NA系统发育树。结果苏州市2018-2019流行季了报告1例人感染H5N6禽流感实验室确诊病例,春节期间W区某地持续出现病死禽经实验室检测确诊为H5N6禽流感疫情。序列分析表明苏州株血凝素(hemagglutinin,HA)及神经氨酸酶(neuramidinase,NA)基因同源性分别为98.01%~100.0%和98.16%~100.0%。A/chicken/Suzhou/WZ01/2019(H5N6)和A/chicken/Suzhou/WZ03/2019(H5N6)均发生了D198N及Q226H耐药突变。苏州H5N6病毒株属2.3.4.4 H5进化分支,HA蛋白切割位点氨基酸序列为RERRRKR↓GLF,为高致病禽流感病毒。结论H5N6高致病禽流感病毒为新型多源重配病毒且仍在不断进化,苏州株多个基因位点发生漂移;应密切监测耐药突变及耐药毒株的流行并及时采取科学有效处置措施防止对公众健康和养殖业造成重大损害。

Objective To analyze host adaptability and drug resistance variation of highly pathogenic avian influenza(HPAI)A(H5 N6)viruses obtained from outbreaks in Suzhou City.Methods Real-time fluorescent quantitative reverse transcription-polymerase chain reaction(RT-PCR)assay was used for influenza virus detection in pharynx or anus swabs of dead birds and suspected cases.Full genome of H5 N6 positive samples were sequenced by using Sanger method.Hemagglutinin(HA)and neuramidinase(NA)phylogenetic trees were constructed by MEGA software.Results A child was laboratory confirmed to have A(H5 N6)viruses infection in November 2018.A outbreak of avian flu in poultry in W district during the Spring Festival was laboratory confirmed as a A(H5 N6)epidemic situation.Avian-origin H5 N6 viruses possessed D198 N and Q226 H resistance mutations.The homology of HA and NA genes of Suzhou strains were 98.01%-100.0%and 98.16%-100.0%,respectively.These H5 N6 strains belonged to 2.3.4.4 H5 clad.Multiple basic amino acid at the cleavage site of HA implied the highly pathogenic characteristics of Suzhou H5 N6 strains.Conclusion H5 N6 is a kind of malti-sourse reassortment virus,which is still evolving.Multiple loci of Suzhou H5 N6 strains of this epidemic were identified to have drifted.The prevalence of drug-resistant mutations should be closely monitored in order to timely take effective measures to prevent serious damage to public health and poultry production industries.