【摘要】 以乙脑弱毒 SA14 -1 4 -2作为母种 ,采用原代地鼠肾细胞和乳鼠皮下传代方法并结合蚀斑纯化技术 ,选育获得乙脑减毒活疫苗猪用毒株 SA14 -1 4 -2 VS株。该毒株经细胞传到 1 5～ 1 8代 ,脑内接种 1 2～ 1 4 g小鼠不引起发病和死亡 ;皮下接种 1 0～ 1 2 g小鼠 ,从脑组织中不能分离出病毒 ;经 3～ 5日龄乳鼠回传一代后 ,脑内毒力 L og L D50 仅为 1 .3 2～ 2 .1 0 ,皮下接种小鼠无致病力。该毒株细胞 1 8代毒 ,用乳猪传至第五代 ,从乳猪血液、脑、肝组织中分离的病毒再经细胞传二代 ,其滴度与原毒液相近 ,并仍对小鼠脑内感染不致死 ;8头小公猪经该毒接种后 ,未发生睾丸炎 ,睾丸组织中未回收到病毒 ;经静脉接种的 2头怀孕 3 0 d的初产母猪 ,虽接种后 2 d和 4d血样中检出病毒 ,但接种 2 1 d剖杀时 ,胎儿均健活 ,胎盘、羊水及胎儿脑组织中均未回收到病毒 ,该毒株能使豚鼠和猪产生较强的免疫应答 ,对小白鼠攻击的保护力比灭活疫苗高 ;纯毒检定及外源因子污染检定结果表明 ,该毒株是纯净的乙脑病毒 ,符合兽用生物制品种毒标准更多还原

【Abstract】 After passaging the live vaccine strain "SA 14 14 2" virus in BHIC cells or subcutaneous tissue of sucking mice and plaque purification technology, a mutant Japanese Encephalitis virus strain of SA 14 14 2VS used for swine had been obtained. Passaging l 5 l8 generations in cells, the virus couldn’t make the mice of 12 14 g sick and die after inoculated into their encephalons. No virus were separated from the mice encephalons after they were inoculated into the subcutaneous tissue of 10 12g mice. Passaging l generation in brains of 3 5 days mice, its virulence was only l .32 2. l Log LD 50 and the strain inoculated subcutaneously had no pathogenicity. The virus of 18 generations in cells was passaged 5 times in new born piglets and the virus separated from blood, encepholon, liver were passaged 2 times in cells, their titres were equal to prime strain and they had no mortality when inoculated in encephalons. The strain was inoculated into 8 male piglets without causing testitis and no virus was isolated again from testicle. The strain was injected into the vein of 2 gilts at 30 days of gestation without examinating virus from blood after 3 or 4 days. The gilts were scalpeled after 21 days, its foetus were all alive, there were no virusseparated again from placenta, amniotic fluid and brain. The strain could induce higher immuning response in guinea pig and swine, the efficiency of protection for mice was higher than the inactive vaccine. According to the results of examination of purification and outer factor contamination, the strain was pure and accord with the standard of virus used as seed of veterinary biology product.更多还原