PRRSV变异株活疫苗和灭活疫苗免疫特性的研究

Immunological characteristics of the attenuated and inactivited vaccine derived from PRRSV mutant strains

为进一步研究猪繁殖与呼吸综合征病毒(PRRSV)变异株疫苗的免疫机理和明确PRRSV变异株活疫苗和灭活疫苗各自的免疫特性,本实验分别采用PRRSV变异株(HuN4)活疫苗和PRRSV变异株(JXA1)灭活苗免疫PRRSV抗原和抗体阴性的健康断奶仔猪,免疫后21d用PRRSV变异株HuN4强毒攻毒,ELISA方法检测血清中PRRSV特异的抗体水平及TNF-α、IFN-α、IL-1、IL-6和CRP细胞因子水平,荧光定量RT-PCR方法检测病毒血症的发生和持续情况,并取主要器官进行病理组织学观察。结果表明:HuN4活疫苗组免疫后14d便可检测到PRRSV特异性抗体,攻毒后5d各细胞因子水平升高,攻毒后21d病毒血症完全消失,免疫后各器官没有明显病理变化,攻毒后临床症状和各组织器官病理变化轻微;JXA1株灭活苗组免疫期间没有检测到PRRSV特异性抗体,攻毒后5d～9d各细胞因子水平升高,攻毒后病毒血症持续存在,免疫后各器官有轻微病理变化,攻毒后临床症状和各组织器官病理变化比HuN4活疫苗组严重,但比对照组明显减轻。本实验表明,HuN4活疫苗能够快速有效的激发机体的体液免疫反应,在抵抗PRRSV变异株HuN4强毒攻毒时,临床症状明显优于JXA1灭活苗。

To evaluate the immune responses and protective efficacy of the attenuated and inacfivited vaccines of PRRSV mutant strains, piglets were immunized with PRRSV mutant strain （HUN4） attenuated vaccine and PRRSV mutant strain （JXA1） inactivited vaccine respectively, and challenged with HuN4 highly virulent strain on 21 day post vaccination （dpv）. Blood samples were collected for detecting PRRSV-specific antibody and TNF-a, IFN-a, IL-1, IL-6, CRP and histopathological tests conducted on selected tissues. The results showed that the HuN4 attenuated vaccine could induce anti-PRRSV antibody on 14 dpv and increase cytokine on 5 dpc, viremia was cleared completely on 21 day post challenge （dpc）, mild clinical symptoms and mild lesions in tissues developed after challenge; In comparison, pigs vaccinated with JXA1 inactivited vaccine induced cytokine increasing on 5 dpc to 9 dpc, but no anti-PRRSV antibodies was detected throughout, most tissues had mild lesions post vaccination, viremia persisted after challenge and the clinical These findings indicated that HuN4 attenuated vaccine could symptom were more serious than in HuN4 attenuated vaccine group. induce rapid and effective humoral responses and was more effective than JXA1 killed vaccine against HuN4 highly virulent strain.