【摘要】 为了研制高致病性猪繁殖与呼吸综合征(HP-PRRS)弱毒疫苗,将高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)TJ株进行了致弱驯化,在Marc-145细胞上对其进行了连续传代,每5～10代进行噬斑克隆纯化病毒。对致弱过程中不同代次病毒进行遗传变异及致病性分析。结果表明,TJ株在致弱过程中各基因均存在不同程度的变异,至第140代,共有58个氨基酸发生突变,同时在非结构蛋白nsp2区域,在不连续的30个氨基酸缺失(481位和533～561位)之后又出现连续120个氨基酸的缺失,与VR-2332相比,该缺失位点位于推定氨基酸序列的628～747位。动物接种试验结果表明,TJ株经Marc-145细胞传至第20代时,病毒对猪的致病性明显减弱,推测TJ株在这一传代过程中非结构蛋白nsp2-nsp5、nsp7和结构蛋白GP5所发生的遗传变异对病毒毒力致弱起到一定作用。更多还原

【Abstract】 To develop an attenuated vaccine against the highly pathogenic porcine reproductive and respiratory syndrome(HP-PRRS) virus,the HP-PRRS virus strain TJ was attenuated by serial passages and plaque cloned every 5 to 10 passages in Marc-145 cells.Genetic variation and pathogenicity of HP-PRRSV strain TJ in the course of attenuation were analyzed.The results showed that the strain TJ sustained various sequence changes during the course of attenuation.Fifty-eight amino acids changes and a new continuous 120 amino acids deletion after the discontinuous 30 amino acids deletion(sites 481 and 533～561) occurred in strain TJ passages 140,and the position of 120 amino acids deletion was between 628 to 747 according to VR-2332.Animal test showed that the pathogenicity of strain TJ passages 20 was attenuated obviously,so we presume that genetic variation in nonstructural protein nsp2-nsp5,nsp7 and structural protein GP5 during the attenuation provides the molecular bases for the observed attenuated phenotype.更多还原