猪源H9N2亚型流感病毒的分离鉴定和遗传进化分析

ISOLATION AND CHARACTERIZATION OF SWINE H9N2 INFLUENZA VIRUSES

2008年10月~2009年3月采集剖检病死猪喉拭样品41份,从中分离鉴定了2株H9N2亚型猪流感病毒,对其进行部分生物学特性的研究、全基因测序和遗传演化分析,发现血凝素（hemagglutinin,HA）蛋白335~338的裂解位点上,A/Swine/Yangzhou/1/08为RSNR,A/Swine/Taizhou/5/08为RSSR,均为典型低致病性禽流感病毒的特征性序列。2株病毒的HA、神经氨酸酶（neuraminidase,NA）、核衣壳蛋白（nucleocapsid protein,NP）、非结构蛋白（nonstructural protein,NS）、血清前白蛋白（prealbumin,PA）和多聚酶蛋白（polymerase protein1,PB1）基因均来源于A/Chicken/Shanghai/F/98,基质蛋白（matrix,M）基因与A/Swine/Yangzhou/1/08的PB2基因来源于A/Quai/Hong Kong/G1/97,值得注意的是A/Swine/Taizhou/5/08的PB2基因虽然可能来源于A/Chicken/Shanghai/F/98但与A/environment/Hunan/1-35/2007（H5N1）的高度同源,生物学特性试验也表明A/Swine/Taizhou/5/08比A/Swine/Yangzhou/1/08毒力强。

Two swine influenza virus H9N2 subtypes were isolated from 41 throat swab samples collected from October 2008 to March 2009.Sequence analysis revealed that at the amino acid position 335 to 338 of HA protein A/Swine/Yangzhou/1/08 possessed the motif RSNR and A/Swine/Taizhou/5/08 possessed the motif RSSR,which were characters of low pathogenic avian influenza viruses.The HA,NA,NP,NS,PA and PB1 genes of the two viruses were all derived from A/Chicken/Shanghai/F/98 while M and PB2 genes of A/Swine/Yangzhou/1/08 were derived from A/Quai/Hong Kong/G1/97.The PB2 gene of A/Swine/Taizhou/5/08 might derive from A/Chicken/Shanghai/F/98 but was highly homologous with A/environment/Hunan/1-35/2007（H5N1）.Besides,the biological characterization suggested that A/Swine/Taizhou/5/08 was more virulent than A/Swine/Yangzhou/1/08.