规模化猪场猪细小病毒的检测及遗传进化分析

Analysis of Genetic Evolution of Porcine Parvovirus in Large Swine Enterprises

为了解广东某规模化猪场猪细小病毒病的感染情况和免疫现状,应用PCR方法对该企业2019年收集的疑似PPV感染的15份流产胎儿的病料组织进行PPV病原检测,对阳性样品进行VP2基因序列分析,同时应用ELISA方法对651份血清样品进行PPV抗体检测。结果显示,PPV病原阳性率为13.34%,同源性分析显示,PPV GD-1株、GD-2株和PPV参考毒株VP2基因核苷酸同源性为97.6%~99.4%;进化树分析显示,PPV GD-1株、GD-2株与3个德国代表株15a株、21a株、27a株亲缘关系最为亲近,处于同一进化分支中。PPV抗体检测结果显示,血清样品抗体总阳性率达89.09%,各年龄阶段猪群抗体阳性率差别较大,阳性率在28.57%~100%之间,其中种公猪和种母猪PPV抗体水平阳性率最高达100%,其次是育肥猪和后备猪分别为97.65%、85.37%,而产房仔猪的抗体阳性率是五个阶段猪群中最低的,仅为28.57%。不同年龄段猪PPV抗体平均值也有所差异,抗体平均值从高至低依次是育肥猪、后备猪、种母猪。产房仔猪PPV母源抗体水平下降速度快,在保育猪到育肥猪这个阶段PPV抗体水平明显上升。结果表明,猪细小病毒VP2基因尽管比较保守,无明显变异,但产房仔猪PPV母源抗体下降快,保育育肥阶段存在PPV的感染风险,所以规模化猪场应重视后备猪猪细小病毒病的免疫防控。

In order to track the infection status and immune status of porcine parvovirus disease in Swine enterprises,15 aborted fetuses suspected to be infected with PPV collected from large scale pig farms of the enterprise in 2019 were detected by PCR,the positive samples were subjected to VP2 gene sequencing analysis.At the same time,the 651 serum samples were detected the antibodies against PPV by ELISA.The results showed that the PPV pathogen detection with a positive rate of 13.34%.Homology analysis showed that the nucleotide homology of VP2 gene of PPV GD-1 and GD-2 strains with the PPV reference strains was 97.6%~99.4%.The phylogenetic tree analysis showed that PPV strains GD-1 and GD-2 were most closely related to the three German representative strains 15A,21A and 27A,which were in the same evolutionary branch.The results of antibodies against PPV detection showed that the antibody-positive rate of serum samples was 89.09%,and the antibody-positive rate of pigs at different age stages varied greatly,ranging from 28.57%to 100%.The positive rate of antibodies against PPV in breeding boars and sows was the highest,reaching 100%,followed by finishing pigs and replacement pigs with 97.65%and 85.37%,respectively.The antibody-positive rate of piglets in the delivery room was the lowest among the five stages,which was only 28.57%.The mean value of antibodies against PPV in pigs of different age groups was also different.The mean value of antibodies against PPV in order from high to low was finishing pigs,reserve pigs and breeding sows.The maternal antibody level of PPV decreased rapidly in piglets in the delivery room and increased significantly from nursery to finishing pigs.The results showed that the VP2 gene of porcine parvovirus was conserved and had no obvious variation,the maternal antibody of PPV decreased rapidly in piglets in the delivery room,and there was a risk of PPV infection in the nursery and fattening stage.Therefore,large-scale pig farms should pay attention to the immune prevention and control of porcine parvovirus disease in reserve pigs.