H3亚型鸭源流感病毒聚合酶PB1基因的序列分析

Sequence Analysis of the PB1 Polymerase Genes of H3 Subtype Duck Influenza Viruses

目的阐明H3亚型鸭流感病毒与其他亚型流感病毒的关系。方法对活禽市场分离的3株H3N8亚型鸭源流感病毒聚合酶PB1基因进行了序列分析。结果3株鸭源H3N8流感病毒聚合酶PB1基因核苷酸同源性为99．9％，与H9N2亚型流感病毒（DK／ST／2143100）的同源性为96．31％-96．44％，而与H3N8亚型鸭流感病毒（Mal／Alberta／279／98）为88．65％-88．79％。系统进化树分析表明，本实验中的3株病毒属于相同的分支，且与刖duck／HongKong／Y439为代表的H9N2亚型禽流感病毒位于一进化分支，说明三株H3N8亚型流感病毒重排了H9N2亚型禽流感病毒的基因片段。结论不同亚型禽流感病毒在贮存宿主体内的重排以及重排病毒的新特点如鸭H3N8亚型流感病毒对禽的致病性，应当引起我们的高度重视。

Objective Aquatic birds are the natural reservoir of avian influenza viruses. There exists a close relationship between the avian and human influenza. There are frequent epidemics of H3 subtype influenza virus among humans and the surveillance show that the carrier rate of H3 subtype influenza virus in aquatic birds is comparatively high. Methods To illustrate the relationship of H3 subtype influenza virus with other subtypes, we carried out the sequence analysis of PB1 polymerase genes of three H3N8 subtype duck influenza virus strains isolated from the live bird markets. Results The results showed that the nucleotide homologies of PB1 gene among the 3 strains of duck virus isolates were 99.9% , and those with H9N2 subtype virus （DK/ST/2143/00） were 96.31% - 96.44% , but those with H3N8 virus （Mal/Alberta/279/98） were 88.65% - 88.79% . The phylogenetic analysis showed that the PB1 genes of these three isolates fell into the same cluster and belonged to the cluster of A/ duck/Hong Kong/Y439- like H9N2 subtype avian influenza viruses, which demonstrated that the gene segments of the three H3N8 subtype viruses reassorted with H9N2 virus strains. Conclussion The present findings suggest that we should pay great attention to the reassortment among different subtypes avian influenza viruses in natural host and the new characteristics of the reassortants, such as the pathogenicity of H3N8 subtype duck influenza viruses to chickens.