猪繁殖与呼吸综合征流行株ORF5基因遗传变异分析

目的]分析猪繁殖与呼吸综合症（PRRS）发病原因、流行趋势，为预防和控制PRRSV提供理论依据。方法]根据GenBank上的猪繁殖与呼吸综合征病毒（PRRSV）ATCCVR-2332的全基因序列，设计并合成引物，采用RT—PCR技术扩增了7株流行株（HIJ10，HL148，HLJ64，HLJ76，HL177，HLJ85，HLJ87）中的ORF5基因序列。应用DNAStar软件分析所测序列，并与ATCCVR-2332、CH-1a、BJ-4、LV及疫苗株MLV进行序列比较。同时用系统进化树分析了分离株之间的亲缘关系。结果]核苷酸序列分析表明这7株流行株中ORF5基因与VR-2332、CH—1a、BJ-4等代表株的同源性分别为88．1％～98．8％，89．9％～95．2％，85．6％～98．7％；与LV的同源性为54．7％～56．9％。氨基酸序列分析表明这7株流行株与VR-2332、CH-1a、BJ4等代表株的同源性分别为88．1％～96．8％，88．1％～94．5％，86．1％～96．5％；与LV的同源性为54．7％～56．2％。通过系统发育进化树分析可知HLJ48、HL164、HLU6、HLJ77、HLJ85与CH-1株亲缘关系密切，同属一亚群，表明所获得的毒株与参考株CH．1亲缘关系较近，可能由CH-1演化而来。HLJ10、HU87与疫苗株MLV关系较近，而且HLJ10、HLJ87的同源性高达100％，可能由于使用疫苗而感染，说明黑龙江省存在疫苗毒的隐性感染。结论]流行株在ORF，基因区域的变异较大，同一地域分离株间ORF，基因序列同源性较高且亲缘关系较近，不同地域则较远。

Analysis on Heredity and Variation of the ORF5 Gene of Prevalence Strains Porcine Reproductive and Respiratory Syndrome Virus

Objective] The aim was to analyze the reason and epidemic trend of PRRSV, and provide theoretical basis for preventing and controlling PRRS. Methed]According to the sequence of ATCC VR-2332 strain porcine reproductive and respiratory syndrome virus published by the GenBank, the primers were designed and synthesized. ORF5 gene sequences of seven prevalence strains were amplified by RT-PCR. The sequences of ORF5 genes were analyzed by DNAStar and compared with those of ATCC VR-2332, CH-1 a, B J-4, LV-M96262 and MLV vaccine strains, phylogenetic tree among isolates was analyzed. Result] Analysis of nucleotide sequence showed that the homology was 88.1% - 98.8%, 89.9% -95.2%, 85.6% -98.7% between ORF5 genes of seven prevalence strains and VR-2332, CH-1a, BJ-4, and the homology was 54.7% -56.9% between ORF5 genes and LV. Analysis of amino acid sequence showed that the homology was 88.1% -96.8%, 88.1% - 94.5%, 86.1% -96.5% between ORF5 genes of seven prevalence strains and VR-2332, CH-1a, bBJ-4, the homology was 54.7% -56.2% between the ORF5 genes and LV. Conclusion] The variation of prevalence strains was great in the ORF5 gene region, the homology of ORF5 gene sequence was higher and genetic relationship was nearer during prevalence strains in the same region, or was far in different regions.