1株野鸟源H7N3亚型禽流感病毒的全基因组序列分析及其对小鼠感染性研究

The complete genomic sequence of a H7N3 subtype avian influenza virus isolated from wild bird and its infectivity in mice

旨在对2021年分离自我国宁夏回族自治区野鸟粪便中的1株低致病性H7N3禽流感病毒(AIV)A/mallard/Ningxia/Y37/2021(H7N3)株进行了全基因组测序、遗传进化分析及对小鼠致病性试验。全基因组序列分析表明,HA基因裂解位点仅有1个碱性氨基酸,符合低致病性AIV的分子特性。遗传进化分析结果表明,HA基因和韩国野鸭源H7N7亚型AIV同源性较高;NA基因与韩国野鸟源H5N3亚型AIV同源性较高;PB2、PA基因与H5N2亚型AIV有较高的同源性;PB1基因与H5N3亚型AIV有较高的同源性;NP基因与H3N2亚型有较高同源性;M、NS基因与H3N8亚型有较高同源性,具有明显的遗传多样性。血凝抑制(HI)试验结果表明,该毒株与H7N9-Re4疫苗株抗血清的HI效价比同源毒株低16倍,抗原性差异显著。小鼠感染性试验结果显示,该病毒能在小鼠的肺部与鼻甲中复制,并引起感染小鼠体重下降,表明该毒株有感染哺乳动物的风险。本试验通过对1株野鸟源H7N3亚型AIV部分生物学特性的分析,为H7N3亚型禽流感的预警和综合防控提供重要理论参考。

In this work,the whole genome,genetic evolution and infectious test to mice of a low pathogenic H7N3 AIV A/mallard/Ningxia/Y37/2021(H7N3)strain isolated from the feces of wild birds in Ningxia Hui Autonomous Region of China in 2021 were analyzed.The whole genome sequence analysis showed that there was only one basic amino acid in the cleavage site of the HA protein,which was in accordance with the molecular characteristics of a low pathogenic avian influenza virus.The results of the genetic evolution analysis showed that the HA gene had high homology with the Korean wild duck H7N7 subtype AIV,and that the NA gene had high homology with the Korean wild bird H5N3 subtype AIV.The PB2 and PA genes had high homology with the H5N2 subtype AIV,and the PB1 gene had high homology with the H5N3 subtype AIV.The NP gene had high homology with the H3N2 subtype,and the M and NS genes had high homology with H3N8 subtype.The results of the hemagglutination inhibition test showed that the HI titer of this strain with H7-Re4 antiserum was 16-fold lower than that of the homologous virus,and the antigenicity of the strain was significantly different from that of the H7-Re4 vaccine strain.The results of the infection test in mice showed that the virus could replicate in the lungs and turbinate of the mice and cause weight loss of the infected mice,indicating that the virus has the risk of infecting mammals.Based on the analysis of some biological characteristics of the H7N3 subtype AIV from a wild bird,this study provides an important theoretical reference for the early warning and comprehensive prevention and control of H7N3 avian influenza.