一例输入型H6N1亚型禽流感的检测分析

Diagnosis and Analysis on Introduced H6N1 Subtype Avian Influenza

为确认进口食品中的禽流感病毒(AIV)携带状况,对从台湾地区进口的冻鸡食品进行了禽流感带毒情况检测,并对病毒进行了分离、全基因组测序和致病性试验。序列分析结果显示:分离的AIV为H6N1亚型病毒,与台湾本地流行的毒株同源性最高;分离株的HA裂解位点基序为PQIATR/G,符合低致病性禽流感病毒的分子特征;HA蛋白受体结合位点处第186、190、226和228位氨基酸残基分别为脯氨酸(P)、缬氨酸(V)、谷氨酰胺(Q)、丝氨酸(S),具有结合人样流感病毒受体的分子特征。SPF鸡试验结果显示,分离株的静脉致病指数(IVPI)为0,为低致病性AIV。Balb/c小鼠感染性结果显示:分离株可在小鼠下呼吸道和肺脏中复制;高剂量感染可使小鼠体重发生轻微变化,但未表现明显临床症状。检测结果表明,该H6N1亚型毒株虽然目前致病力较弱,但有突变为高致病性毒株风险,对人类和家禽存在潜在威胁。

In order to confirm the infective condition of Avian infiuenza virus（AIV）in imported food,AIV detection was conducted towards the imported frozen food from Taiwan,and virus isolation,whole-genome sequencing and pathogenicity tests were also carried out. Sequence analysis showed that the isolated AIV strain was H6N1 subtype,which had the highest homology with the pandemic strain in Taiwan. The sequence motif in HA cleavage site of the isolated strain was PQIATR/G,which conformed to the molecular characteristic of the low pathogenic AIV. The amino acid residues in position 186, 190, 226 and 228 of the HA protein receptor binding sites were proline （P）, valine （V）,glutamine（Q）and serine（S）,respectively,showing the molecular characteristics of binding to human-like receptors. In addition,the SPF chicken test showed that the IVPI was 0,indicating the virus was low pathogenic. The infectious experiments of Balb/c mice showed that the virus could replicate in the lower respiratory tract and lungs. And high dose of virus could cause slight weight lose of mice,but no obviously clinical symptoms were found. Detection results showed,although the pathogenicity of H6N1 subtype AIV was low at present,it was still possible to mutate to highly pathogenic form,which would brougt potential threats to human and polutry health.