我国南方猪高热病的研究(Ⅱ)——猪繁殖与呼吸障碍综合征病毒的分离、鉴定和致病性测定

Research on Swine High Fever without Confirmed Pathogen(Ⅱ)——Isolation、Identification and Pathogenic Test about Porcine Reproductive and Respiratory Syndrome virus

从我国南方某猪场高热病死猪的组织中分离出能引起Mare145细胞病变的病毒，经过血清中和试验、RT-PCR测定，确定分离物中存在美洲型猪繁殖与呼吸障碍综合征病毒（PRRSV）。将细胞病毒液感染13头55—105日龄健康猪，另有3头健康猪用于同居感染。随意挑取13头中7头再用大肠杆菌培养物加强感染，感染后每天测温，观察临床症状，记录死亡情况和病理变化。结果表明：PRRSV单独感染猪6／6发病，5／6死亡；大肠杆菌与PRRSV混合感染猪7／7发病，5／7死亡；同居感染的3头全部发病，1头死亡。所有感染猪于感染后2—4d内均出现体温升高。两周后体温下降至正常，直到死亡前体温不再升高。死亡多集中在感染后的34—50d的2周时间内。将圈舍温度升至29℃对感染猪发病无加强作用。死亡猪的病理变化主要表现为严重的出血性、间质性肺炎，肢体远端皮表出血。结果表明，虽然PRRSV感染能够引起猪产生高热和高的发病死亡率，但从发病到死亡时间及某些病理变化上看，和南方猪场的发病死亡猪还存在一定的差异，这可能与猪场的一些激发因子或其他病原混合感染有关，从组织和细胞分离物的电子显微镜照片也证明了这一点。

A virus strain was isolated by Marc-145 cell lines from dead pigs with swine high fever disease in south China. The virus was identificated by serological neutralization, RT-PCR and electricitic microscope, the result showed that it was porcine reproductive and respiratory syndromevirus （PRRSV）. 13/16 healthy pigs （55 - 105 days） were infected by the PRRSV, and in order to reinforced the infection, 7/13 pigs were injected by Escherichia coli （E. coli）. Body temperature was measured and clinic symptoms were noted ereryday. 6/6 pigs in the group infected by PRRSV appeared classical symptoms, and 5/6 died. 7/7pigs in the group challenged by PRRSV and E. coli appeared classical symptoms, 5/7 died. 3/3 contagion pigs appeared classical symptoms, and I/3 died. All the infected pigs＇ temperture risesd in 2 ～4 d, most pigs died in 34 ～50 d. Interstitial pneumonia ,carnification, haemorrhage in all dead pigs＇ lung, are the features of anatomy, The result indicated that PRRSV was the major cause of swine high fever without confirmed pathogency in south China, although there were different feature in our laboratary with some disease prevalence areas in south China.