高致病性猪繁殖与呼吸综合征病毒四川变异株致病性分析

摘要

为探究高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)四川变异株SC2012和SC2012-2人工感染仔猪的病理学特征及其在组织内的分布情况,本研究将HP-PRRSV SC2012和SC2012-2株接种健康断奶仔猪,观察不同发病阶段仔猪的临床症状;感染后第14d剖检仔猪观察其器官病变情况、组织切片的病理学变化,通过免疫组化方法(IHC)和RT-PCR方法检测PRRSV在组织中的分布情况.结果显示,两组仔猪感染后均未出现显著的呼吸症状,并于感染后3d～5d出现轻微腹泻;体温测定结果显示,两组仔猪均出现轻度发热、病毒血症,但SC2012-2组较SC2012组仔猪出现时间提前、病毒滴度高、维持时间长;两组仔猪均能够通过唾液、粪便、鼻分泌物排毒;剖检仔猪肺脏均出现不同程度的间质性肺炎,肝脏表现为肝淤血,其它多个器官均有不同程度的炎性细胞浸润;临床症状和病理损伤等结果表明,SC2012较SC2012-2株毒力弱.组织内病毒分布结果显示,两株病毒均在多个器官中分布,但结合组织病理变化分析显示病毒的分布并不一定导致组织损伤,HP-PRRSV四川变异株的突变对其毒力产生了一定的影响.本研究为进一步对HP-PRRSV SC2012和SC2012-2的研究提供必需参数.%To investigate the pathological features of piglets infected artificially with variants HP-PRRSV (SC2012 strain and SC2012-2 strain) and the viral location characteristics in the tissues,healthy piglets were inoculated with the two strains respectively,and the clinical symptoms in different infected stages were observed.Fourteen days post infection,the piglets organ damage and pathological changes of tissues were observed.The location of the viruses in infected tissues were detected by IHC and RT-PCR.The results showed that,no significant respiratory symptom was found in the two infected groups but with a mild diarrhea after infection 3 to 5 days.The measurement of animal temperature in two infected groups showed a mild fever.Both of them were detected with viremia,but the viremia in group infected with SC2012 strain was earlier,higher content and longer persistence when compared with the other group.And viruses in two infected groups could be released and transmitted through the saliva,feces,nasal secretions.In addition,different degrees of interstitial pneumonia of lung and the congestion of liver were observed,and other organs also had different degrees of inflammatory cell infiltration.The result of clinical symptoms and pathological damage demonstrated that the virulent of SC2012 strain was lower than SC2012-2 strain.And the result of location of viruses in the different tissues showed that the two viral strains diffused in multiple organs,but the tissue damage was not necessary for the viral location.In summary,the mutation of the variants HP-PRRSV strains in Sichuan effected the virulent of viruses.And our study provided a dataset for the further study on SC2012 strain and SC2012-2 strain.