猪繁殖与呼吸综合征病毒和猪圆环病毒2型猪体共感染发病模型的建立

Establishment of coinfection model of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2 in pigs

猪繁殖与呼吸综合征病毒(PRRSV)与猪圆环病毒2型(PCV2)多以混合感染的形式,广泛存在于世界各地的猪群。本研究选取35日龄的阴性健康猪,随机分为4组:PCV2感染组(n=5)、PCV2+PRRSV共感染组(n=5)、PRRSV感染组(n=5)和空白对照组(n=4)。攻毒后每天测量体温、观察临床症状,每周称量体重并于不同时间采血,攻毒后第21天剖杀所有猪,荧光定量PCR检测血清中病毒血症和组织中病毒载量。结果表明,PCV2+PRRSV共感染组猪的临床症状最严重,并死亡2头。病理变化主要表现为肺出血、明显的间质性肺炎,淋巴组织及淋巴细胞缺失严重,淋巴滤泡中出现大量核浓缩深染的淋巴细胞;PCV2单独感染组与PRRSV单独感染组猪的临床症状轻微,仅出现短暂性体温升高;空白对照组未出现症状。病毒血症检测结果显示,两种病毒共感染组猪的血清中PCV2与PRRSV含量均高于单独感染组。本研究成功建立了PRRSV与PCV2猪体人工共感染发病模型,为PRRSV与PCV2协同致病机理研究奠定了基础。

It is very popular that coinfection of porcine reproductive and respiratory syndrome virus（PRRSV） and porcine circovirus type 2 （PCV2） exists in field cases. In this study,nineteen 5-week-old healthy pigs free of PRRSV and PCV2 were randomly divided into four groups：pigs coinfected with PRRSV and PCV2 （n=5）;pigs infected with PRRSV alone;pigs infected with PCV2 （n=5） alone;negative co- ntrol（n=4）,and observed for 21 days. The results showed that pigs coinfected with PRRSV and PCV2 sh- owed obvious clinical symptoms,including growth retardation,severe respiratory distress,and two had died at19-20 dpi. The main microscopic lesions included severe proliferative interstitial pneumonia in lungs and lymphoid depletion,necrotizing hepatitis,mild necrotizing bronchiolitis and infiltrates of macrophages in lymphoid. In contrast,the pigs infected with PRRSV or PCV2 alone showedmoderate gross lesions and histopathological changes of lungs and lymph nodes. Meanwhile,the loads of PRRSV and PCV2 in the pigs doubly inoculated were higher than those inoculated with PRRSV or PCV2 alone. This coinfection model should be very usefully to study on the pathogenesis of PRRSV and PCV2 and development of new vaccines against these diseases in the future.