两株鹅源H6N2亚型禽流感广东分离株的全序列分析及致病性研究

为了解禽流感病毒(AIV)的变异情况,本研究对我国禽流感监测期间分离鉴定的两株鹅源AIVA/Goose/Guangdong/362/2009(H6N2)(GD/362/09)与A/Goose/Guangdong/244/2010(H6N2)(GD/244/10)进行全基因序列的测定和分析,并进行其对SPF鸡和BALB/c小鼠的致病性试验。序列分析显示:HA裂解位点的序列为339PQIETR↓GLFG348,表明两株病毒均为低致病力AIV。HA和NA的核苷酸同源性分别为84.5%和98.9%,另外,序列分析结果显示,GD/244/10的PA、M基因分别与高致病性AIV(HPAIV)A/aquatic bird/Korea/w74/2005(H5N2)和A/duck/Hong Kong/140/1998(H5N1)的同源性最高,表明其内部基因来源复杂,可能与H5 HPAIV发生重组或有共同的来源。病毒对动物的致病性试验结果显示:两株病毒均不能在鸡体内有效复制,在小鼠的肺脏能够有效复制,但在小鼠的鼻甲内只能检测到GD/244/10。

Sequence analysis and pathogenicity of 2 H6N2 subtype AIV isolates from geese in Guangdong

To study the variation of avian influenza virus(AIV),two AIVs(GD/362/09 and GD/244/10) of H6 subtype isolated from goose during the epidemiological survey were sequenced and analyzed.The sequencing results showed that both the isolates had the HA cleavage site of 339PQIETR↓GLFG348,which was a characteristic structure of low pathogenic AIV,and the nucleotide homology of HA and NA gene between GD/362/09 and GD/244/10 were 84.5% and 98.9%,the PA and M gene of GD/244/10 share the highest homology with that of A/Aquatic bird/Korea/w74/2005(H5N2) and A/Duck/Hong Kong/140/1998(H5N1),which indicated that it evolved from the same parent or reassortment had already occurred between the H6 and H5 subtype.Pathogenicity was examined by experimental infection of SPF chickens and BALB/c mice intranasally with 106 EID50/100 μL or 106 EID50/50 μL,respectively.The results showed that both the H6 AIVs of goose origin failed to replicate in chickens,but they were able to replicate in mouse lung efficiently and only GD/244/10 was detected in mouse turbinate.