猪繁殖与呼吸综合征病毒接触感染仔猪模型的建立

Generation of piglet model for porcine reproductive and respiratory syndrome virus contagious infection

为了建立猪繁殖与呼吸综合征病毒(PRRSV)接触感染模型,将易感仔猪与PRRSV人工感染仔猪在隔离器中同居饲养,每日观察记录体温变化和临床症状,定期采集血清和粪便样品,用荧光定量RT-PCR检测病毒血症和粪便排毒水平;对病死猪和试验结束迫杀猪进行剖检和肺脏组织病理学检查,并检测各器官病毒载量和组织分布。结果显示:接触感染仔猪出现高热和PRRS症状时间分别较人工接种猪推迟2~3d;第3天起血清检测PRRSV阳性,第10天病毒血症上升至较高水平(108.6拷贝/mL);第5天起粪便检测PRRSV阳性,第7天粪便排毒量上升至较高水平(103.9拷贝/0.1g);3头接触感染仔猪分别于同居后第12天和第13天死亡,较人工接种猪推迟1~2d,病死猪的主要器官病毒载量以及剖检和肺脏显微病理变化与人工接种病死猪相似。这些结果表明,本研究建立的接触感染仔猪模型可用于PRRS疫苗免疫效果评价。

To generate the piglet model for porcine reproductive and respiratory syndrome virus(PRRSV)contagious infection,PRRSV-negative piglets were housed with artificially infected piglet in the isolator.Rectal temperatures and clinical signs were recorded daily.Serum and fecal samples were collected regularly for PRRSV detection by quantitative RT-PCR.Lungs of died or culled piglets were examined pathologically and the PRRSV loads in different tissues were detected.Results showed that the high fever and PRRS symptoms of infected pigs were delayed by 2 or 3 days respectively compared to the donor piglet.From day 3 after cohabitation,viremia was detected in all piglets,which reached to a high level(108.6 copies/mL)at day 10.Fecal samples were positive for PRRSV from day 5,and reached to a high level(103.9 copies/0.1g)at day 7.Three piglets died at day 12 or 13 after contagious infection,which was delayed by 1 or 2 days compared to the donor piglet.The macroscopic or microscopic pathological changes of lungs and viral loads in different organs were similar to the donor piglet.These data suggest that the piglet model for PRRSV contagious infection is usable to evaluate the protective effect of PRRSV vaccine.