免疫刺激商品断奶仔猪复制多系统衰竭综合征(PMWS)

Experimental Reproduction of Postweaning Multisystemic Wasting Syndrome(PMWS) in Commercial Piglets with Porcine Circovirus 2

猪圆环病毒2型(PCV2)是引起PMWS的必需病原,与其他病原混合感染或受到外界刺激时表现PMWS临床症状。本试验将16头商品化断奶仔猪(32日龄)随机分为4组(每组4头),即对照组、钥匙孔血蓝蛋白刺激组、PCV2攻毒组和PCV2攻毒后钥匙孔血蓝蛋白刺激组,用上海某猪场分离株PCV2-SH、钥匙孔血蓝蛋白(KLH)反复刺激断奶仔猪以复制PMWS。其中对照组、钥匙孔血蓝蛋白刺激组未出现症状;PCV2攻毒组症状较轻,出现增重缓慢,伴有短暂的体温升高;而PCV2攻毒后钥匙孔血蓝蛋白刺激组出现明显的临床症状,2头猪在攻毒后第11天濒临死亡,其中1头在第12天死亡,攻毒猪宰杀后脏器出现明显的病理变化。PCV2攻毒组和PCV2攻毒后钥匙孔血蓝蛋白刺激组于攻毒后第4天出现病毒血症,宰杀后肺脏、淋巴结均检测到PCV2的DNA。以上结果说明,PCV2-SH感染结合免疫刺激可以引起商品化仔猪发生PMWS,为PCV2致病机理和免疫学研究提供了动物发病模型。

Postweaning multisystemic wasting syndrome（PMWS） is a disease of nursery and fattening pigs characterized by growth retardation,paleness of the skin and dyspnea.It has been demonstrated that PCV2 is the cause of PMWS.The expression of the disease is dependent on the co-infection with PCV2 and other factors or immunostimulation.In this study,32-day-old postweaning piglets without antibody to PCV2 were inoculated intranasally with PCV2.The effect of immunostimulation on the induction of PMWS was investigated by immunization with keyhole limpet hemocyanin（KLH） emulsified in incomplete Freunds adjuvant.Sixteen piglets were distributed to four groups,each with four： control,PCV2,PCV2＋KLH and KLH.The results showed that the 2 groups inoculated with PCV2 showed growth retardation.But the clinical signs of pigs in the group inoculated alone with PCV2 were not clearer than those in group with PCV2＋KLH.Pigs inoculated with PCV2 and immunostimulated with KLH had increased rectal temperature,and one of these pigs developed wasting and died in day 12 after challenge.PCV2 viremia was found from 4 days after challenge to the end of the experiment.PCV2 nucleic acid was found in the lung and lymph node from the pigs of two groups inoculated with PCV2 by PCR.Meanwhile,the pigs in the groups inoculated with KLH alone or control had no clinical sign and pathogen.It confirmed that PCV2 is the primary viral infectious agent of PMWS.