猪繁殖与呼吸综合征病毒新结构蛋白基因ORF5a分子特征

Sequence Analysis of ORF5a,a New Structural Protein Gene of Porcine Reproductive and Respiratory Syndrome Virus

本研究采用RT-PCR方法从临床病料中扩增得到了5株猪繁殖与呼吸综合征病毒（PRRSV）山东流行株新结构蛋白ORF5a基因序列,并与国内外其他22株PRRSV ORF5a基因序列进行了比较和分析。结果表明,5株PRRSV山东株ORF5a基因CDS为141 bp,编码46个氨基酸,序列同源性为93.6%~100%（nt）和89.4%~100%（aa）;5株山东株与其他Ⅱ型PRRSV同源性为83.0%-99.3%（nt）和72.3%~100%（aa）。在ORF5a蛋白上高度保守的R/Q基序区,LX13（3）株有3个氨基酸的变异,CY13株有1个氨基酸的变异。与2006年以前的毒株相比,我国2006年以后分离的毒株第8、12、28位和42位的氨基酸发生了变异。进化树分析表明,5株PRRSV山东株与高致病性PRRSV代表株JXA1株在同一个亚群。

ORF5a gene sequences of five PRRSV strains were obtained from Shandong Provinces by RT-PCR and sequencing.ORF5 a gene variation of the 5 isolates and other 22 published PRRSV isolates was analyzed.The results showed that the 141 bp ORF5a gene of 5 isolates shared 93.6%~100% nucleotid（nt）and 89.4%~ 100% amino acid（aa） identity with each other,while have 83.0%~99.3%（nt） and 72.3% ~ 100%（aa） homology with those published strains（type Ⅱ PRRSV）.mutations mutations occurred in strain LX13（3） at R/Q motif,for strain CY13,and 1 mutation was found in the strain CY13.Compared with strains isolated before 2006,amino-acid mutations at position 8,12,28 and 42 were observed.Phylogenetic analysis suggested that the 5 isolates belonged to the same subgroup with JXA1,the representative strain of highly pathogenic PRRSV.