H9N2亚型禽流感病毒的遗传进化分析及F株灭活疫苗的免疫效果评价

Phylogenetic analysis of H9N2 subtype avian influenza viruses isolated from immunized chicken flocks and protective efficacy of F strain inactivated vaccine

为了解H9N2亚型禽流感病毒(AIV)变异情况及评价作为H9亚型F株禽流感灭活疫苗的免疫效果,本研究对2009年～2010年期间从免疫鸡群中分离的9个H9N2亚型AIV株进行血凝素(HA)基因序列测定和分析。这9个病毒株HA基因编码区长度均为1 683 nt,HA基因核苷酸序列同源性为90.7%～98.9%,其推导氨基酸序列同源性为92.2%～98.8%;分离株与F株的HA基因之间的核苷酸序列同源性为91.6%～99.6%,氨基酸序列同源性为92.9%～99.3%;9个分离株与F株均属于Beijing/1/94-like进化分支,但分别属于3个不同的基因亚型。免疫试验结果显示:3周龄SPF鸡接种F株灭活疫苗21 d后,产生的HI抗体效价在log2 9以上;而且免疫鸡对分离株及F株攻毒后的喉头和泄殖腔排毒产生明显的抑制作用。本研究数据表明,F株灭活疫苗可以提供对这些分离株的有效免疫保护。

To investigate the phylogenesis and antigenic relationship of H9N2 avian influenza viruses（AIV）,the hemagglutinin（HA） genes of 9 isolates from immunized chicken flocks in China during 2009 to 2010 were sequenced and analyzed.The HA genes were 1,683 nt in length,sharing 90.7% to 98.9% nucleotide acid homology and 92.2% to 98.8% amino acid homology.There were high sequence similarities between these isolates and the vaccine strain（F）,with 91.6%-99.6% identities at nucleotide acid level,and 92.9% to 99.3% identities at amino acid level.All isolates belonged to the Beijing/1/94-like lineage and could be divided into three genotypes.Commercial subtype H9 inactivated vaccine（F strain） could stimulate the high antibody titers in SPF chickens and markedly reduced the virus shedding after challenge with H9N2 AIV isolates.