1株鹅源H9N2亚型禽流感病毒分子进化分析及对鹅的致病性

Molecula revolution analysis and animal challenge test of one goose source H9N2 subtype avian influenza virus

从广东地区鹅群采集的咽喉拭子中分离到1株H9N2亚型禽流感病毒（AIV）并命名为A／Goose／Guangdong／A11／2016（H9N2）（GS／A11）。采用RT—PCR方法扩增出病毒的全基因片段，并进行序列比较及遗传进化分析。推导氨基酸序列分析表明，GS／A11的HA蛋白裂解位点序列为^333PSRSS↓GL^340，无连续碱性氨基酸，符合低致病性禽流感特征；GS／A11上的Q226L突变提示结合人α-2，6唾液酸受体的能力增加；M2蛋白中出现了与金刚烷抗性相关的S31N突变。基因遗传进化树分析显示，分离株病毒为三元重组基因型。为了解H9N2亚型对鹅的致病性，以10^9×EID80剂量经静脉注射6周非免疫鹅，攻毒显示，攻毒鹅无明显临床症状，仅表现为局部器官感染，可经喉气管和泄殖腔排毒。研究提示，该株H9N2亚型AIV对鹅无明显致病力，但感染后可持续排毒。该现象为流感病毒在鹅及其他禽类中流行并发生基因重组提供了机会，故应加强鹅H9N2亚型AIV的检测及分子遗传的演变监控。

In this study, one strain of H9N2 subtype avian influenza virus A/Goose/Guangdong/ A11/2016（H9N2） （GS/A]I） was isolated from a goose in Guangdong. The whole viral genomic sequences of the virus were obtained through RT-PCR. Amino acid sequence analysis showed that the sequence of cleavage sites on the hemagglutinin （HA） protein of the virus was ^333PSRSS↓GL^340（GS/All）,indicating that the virus could be considered as a low pathogenic strain. Comparing with vaccine strains, mutation of Q226L on HA protein of GS/A11 suggested an enhancing humana-2,6 sialic acid receptors binding ability. S31N mutations in the M2 protein that associated with adamantane resistance was found in the virus. The phylogenetic analysis showed that the isolated virus was a ternary recombinant genotype. In order to understand the pathogenicity of GS/ All on goose,106EID50 virus were challenged into 6 weeks old non-immune goose,through i. v. injection. The animal of challenged group showed no significant clinical symptoms. Virus could be isolated and titrated from the swabs collected from throat, trachea and anus,at 2,4 and 6 days after challenge. In summarizes,the newly found H9N2 strain had a low pathogenicity against goose, but the virus shedding may provide opportunities for genomic reassortant between multiple subtypes of influenza viruses. Therefore,strengthen should be hold on the detection of goat HgN2 subtype AIV and molecular genetic evolution monitoring in geese of Guangdong province.