猪繁殖与呼吸综合征病毒ORF5基因的遗传变异和系统进化分析

Genetic variation and phylogenetic analysis of ORF5 gene of porcine reproductive and respiratory syndrome virus in China

猪繁殖与呼吸综合征病毒(PRRSV)毒株间变异广泛,而且这种变异能够筛选出强毒株。在结构蛋白中GP5的变异率最高,其变异能够导致病毒毒力的变化。为了确定PRRSV在我国的进化趋势和毒力增强的原因,对从2003年以来分离到14株PRRSV GP5蛋白的核苷酸序列和推导的氨基酸序列进行分析并构建了系统进化树。结果显示2006年以来从国内分离的毒株其糖基化位点发生了明显改变,并且在系统进化树上形成了新的分支,进化分析显示它们可能来源于1995年的中国分离株CH-1 a。

Extensive genetic variations have been found among porcine reproductive and respiratory syndrome virus （PRRSV） isolates. The variations could lead to the emergence of more virulent strains of PRRSV. In order to determine the evolutionary trend and the causes for increasing virulence of PRRSV, nucleotide sequences and derived amino acids sequences of GP5 proteins from 14 strains were analyzed and phylogenetic tree was constructed. The results showed that the glycosylation sites at amino acid 26 to 39 among the isolates from 2006 were changed and the isolates formed a new minor branch in phylogenetic tree. Phylogenetic analysis indicated the isolates may be originated from CH-la, which was isolated from China in 1995.