巴马香猪超前免疫高致病性猪繁殖与呼吸综合征弱毒疫苗的免疫效果评价

Evaluation of immunization efficacy of Bama miniature pigs by advanced immunization with highly pathogenic porcine reproductive and respiratory syndrome modified-living vaccine(JXA1-R)

为了评价高致病性猪繁殖与呼吸综合征弱毒疫苗(JXA1-R)对仔猪超前免疫的免疫效果及安全性,给3头巴马香猪超前免疫弱毒疫苗JXA1-R 1头份/头,以3头同窝仔猪为对照组,接种等量疫苗稀释液,观察疫苗免疫后的临床表现,测定疫苗免疫后的抗体动态变化及排毒情况;免疫后第35天,采用高致病性猪繁殖与呼吸综合征病毒(JXA1)攻毒,测定攻毒后的抗体变化、排毒情况及免疫保护作用。结果表明,巴马香猪超前免疫后第14天发生抗体阳转,鼻拭子样品、肛门拭子样品和血清样品中均检测到病毒核酸,同居的阴性对照组中有1头仔猪发生抗体阳转,提示该疫苗存在排毒现象。攻毒前免疫组和对照组的抗体阳性率分别为3/3和1/3;攻毒后免疫组和对照组的免疫保护率分别为3/3和1/3,表明该疫苗具有一定的免疫保护作用,但初生巴马香猪超前免疫后表现生长缓慢,被毛粗乱,提示该疫苗对仔猪具有一定的毒力,不适合用作超前免疫。

Safety and potency of advanced immunization with the highly pathogenic porcine reproductive and respiratory syndrome modified-living vaccine（PRRS MLV JXA1-R） were detected in Bama miniature pigs.In the immunization group,the advanced immunization was performed on three Bama miniature pigs with 1 dose of PRRSV MLV（JXA1-R）.The control groups consisted of three piglets from the same brood,which were immunized with the same diluent.Then the clinical manifestations of the groups were observed.The antibody dynamics were detected by PRRSV antibody kit（ELISA）.On day 35 post-vaccination,the immunization group was challenged with the high-virulent PRRSV isolate（PRRSV JXA1）.The immunization efficacy and antibody were detected.On day 14 post-vaccination,the antibody turned to positive,and the viral nucleic acid could be detected in nasal swab specimens,anus swab samples and blood while the antibody of one pig in the control group turned to positive,which was raised the same brood with the piglets of the vaccine group,indicating that the PRRS MLV（JXA1-R） might spread the virus.The positive rate of the antibody in the immunization group and the control group were 3/3 and 1/3,respectively.While the protective rate of the 2 groups were 3/3 and 1/3,respectively.These results demonstrated that the PRRS MLV（JXA1-R） could achieve some protective effect while the immunized piglets grew to be retarded along with disorderly pelage,indicating that the PRRS MLV（JXA1-R） had virulence to piglets and it was unsuitable for advanced immunization.