摘要
从过去10年由中国中部分离的具有不同致病力的25株H9N2亚型禽流感选出6株（3#、12#、25#、14#、4#、22#）代表性毒株,利用RT-PCR扩增它们的HA基因,并比较分析该基因的序列,旨在探讨HA基因的变异对AIV毒力、抗原性变化的影响。结果表明：6株H9N2 AIV亚型分离株的HA基因在HA1和HA2的氨基酸裂解位点上没有出现高致病性禽流感病毒所特有的R-X-R/K-R模式,它们均为弱毒力毒株。HA上潜在糖基化位点除了3#和12#分离株多出一个之外,其余均为8个。3#和12#所表现出较强的致病性可能与其在HA的头部（HA1）的A抗原位点上多了一个糖基化位点（145147aa）,改变了HA基因空间构型有关,空间构型的改变导致抗HA抗体作用位点的变异或缺失并影响其较近的受体结合位点,从而改变该毒株的抗原性。研究结果提示需要持续跟踪H9N2 AIV在中国鸡群中的传播和进化,以便及时掌握疫情,有效防控禽流感。
The purpose of this study is to explore the effects of the HA sequence variation on the pathogenicity and antigenicity of avian influenza virus（AIV）.Haemagglutinin（HA） genes from,6 of 25 avian influenza viruses（AIVs） H9N2 strains with different pathogenicity isolated in central China during last 10 years were amplified by reverse transcriptase PCR（RT-PCR）,completely sequenced and phylogenetically analyzed.The purpose of this study was to explore the effects of the HA sequence variation on the pathogenicity and antigenicity of AIV.The results showed that all 6 representative H9N2 isolates belong to low pathogenic AIVs,since none of the amino acid sequences at the cleavage site of the HA of the isolates possessed the basic motif required for highly pathogenic viruses（R-X-R/K-R）.There were eight potential glycosylation sites in HA of the isolates,except that 3# and 12# had an extra one.The higher pathogenicity of 3# and 12# was probably due to the extra glycosylation site（145aa-147aa） in HA1,which might alter the conformational structure of HA resulting in the mutation or deletion of the binding sites of anti-HA antibody,and has effects on receptor binding sites thus changed the antigenicity of the virus.Our results suggested that attention should be paid to the transmission and natural evolution of H9N2 AIV in order to control AIV H9N2.
出处
《病毒学报》
CAS
CSCD
北大核心
2011年第2期122-128,共7页
Chinese Journal of Virology
基金
农业科技成果转化资金项目(2008GB2D000182)
