一株H9N2亚型禽流感病毒全基因组序列的遗传变异分析

Genetic Variation Analysis on the Whole Genomic Sequence of a H9N2 Subtype Avian Influenza Virus Isolate

[目的]了解H9N2亚型禽流感病毒分离毒株A／Chicken／Hebei／WD／98（简称WD98）与其他参考毒株的遗传变异关系。[方法]采用RT—PCR技术扩增了WD98分离株8个基因片段的全基因序列，并将其与7个参考毒株进行同源性比较及遗传进化分析。[结果]分离株WD98与7个参考毒株全基因组同源性为91．1％～95．8％，与A／duck／HongKong／Y280／97的全基因组核苷酸同源性最高（95．8％），而与A／chicken／Pakistan／2／99同源性最低（91．1％）。WD98株的HA基因裂解位点为R—S-S—R↓G，其第226位受体结合住点为Q。[结论]禽流感病毒WD98毒株为低致病性禽流感病毒，不易感染人，与A／duck／HongKong／Y280／97亲缘关系最近，同属于欧亚种系A／Chicken／Beijing／1／94亚系。而在这同一亚系中，WD98株与A／Chicken／Beijing／1／94株的亲缘关系最远。

[ Objective ] To understand the genetic variation characters of the H9N2 subtype avian influenza virus isolate （ A/Chicken/Hebei/ WD/98, WD98 for short） by comparing with other reference strains. [ Method] The eight complete genes were amplified by RT-PCR and sequenced. The homology and genetic evolution relation were analyzed between these sequences and that of the seven reference strains. [ Result] The whole genomie sequence of the WD98 strain was 91.1% -95.8% homologous to that of the seven reference strains. This isolate shared the highest homology （95.8%） to D/HK/Y280/97 and the lowest homology （91.1%） to C/Pak/2/99. The HA cleavage site of the WD98 strain was R-S-S-R ↓ G, and the 226th amino acid at receptor-binding site was Q. [ Conclusion ] The WD98 strain belongs to mildly pathogenic avian influenza virus and may not infect human. The genetic relationship is closest between A/Chicken/Hebei/WD/98 and A/ duck/HongKong/Y280/97, both of which belong to the sub-line of A/Chicken/Beijing/1/94 in Eurasian line. And A/Chicken/Hebei/WD/ 98 andA/Chieken/Beiiinz/1/94 ＇are farthest related in the same sub-line.