2012年－2014年闽西地区 PRRSV 流行株ORF5基因遗传变异分析

摘要

为了研究2012年－2014年闽西地区猪繁殖与呼吸综合征病毒(PRRSV)流行毒株的分子生物学特性和变异规律,对分离自闽西多个地区25份疑似 PRRS 病料的10个 PRRSV 分离株,应用 RT-PCR 对其中 ORF5基因进行扩增及序列分析,从而了解闽西地区 PRRSV 的遗传变异性.结果表明,10个毒株均为美洲型 PRRSV,9株 PRRSV ORF5基因全长为603 bp(FJ05 为600 bp),10个毒株 ORF5基因之间的核苷酸同源性为88．4％~99．3％；与 VR-2332、MLV 和 CH-1a 毒株的核苷酸同源性为88．3％~98．8％,与我国高致病性代表毒株 JXA1、WUH1、HUN4等的同源性为88．9％~99．0％,与欧洲型毒株代表毒株 LV 的同源性为63．8％~65．0％.ORF5基因推导氨基酸序列变异主要发生在9-40位和58-62位,10株 PRRSV ORF5氨基酸同源性为88．5％~99．5％；与 VR-2332、MLV 和 CH-1a 的氨基酸同源性为87．5％~98．5％,与我国高致病性代表毒株 JXA1、WUH1、HUN4等的同源性为88．0％~99．5％,与欧洲型毒株代表毒株 LV的同源性为56．6％~59．2％.遗传进化树表明,闽西地区 PRRSV 可以分为疫苗株(1株,10％)、中等毒力PRRSV(1株,10％)和 HP-PRRSV(8株,80％)3个亚群,其中以 HP-PRRSV 为主,表明闽西地区 PRRSV流行毒株呈现遗传变异多样性.%The result showed that 10 PRRSV isolates belonged to the North American genotype,the lengths of the nine ORF5 sequences were 603 nucleotides (FJ05 is 600 nucleotides).Ten isolates displayed a nucleotide identity ranging from 88.4% to 99.3% among themselves,they shared 88.3%-98.8% homolo-gy with VR2332,MLV and CH-1a;88.9%-99.0% with JXA1,WUH1 and HUN4,and they shared only 63.8-65.0% with LV.High variable occurred at positions of 9-40 aa and 58-62 aa of GP5.Amino acid se-quence alignments revealed that 10 isolates shared 88.5%-99.5% among themselves,they shared 87.5%-98.5% homology with VR-2332,MLV and CH-1a,88.0%-99.5% with JXA1,WUH1 and HUN4,howev-er,they shared only 56.6-59.2% with LV.The phylogenetic tree analysis showed that 10 isolates are divid-ed into three subgroups,8 strains (8/10,80%)belonged to subgroup Ⅰ,which are closely related to the JXA1 strain.The FJ01 strain (1/10,10%)belonged to subgroup Ⅱ,which is closely related to the VR-2332,FJ03 strain (1/10,10%)belong to subgroup Ⅲ,which is closely related to the HB-1sh/2002 (the intersubgenotype).These results showed that PRRSV have been shown to undergo remarkable genetic di-versity.