猪细小病毒N株的生物学和免疫学特性研究

猪细小病毒N株是从广西初产母猪所产死胎脏器分离的自然弱毒株。用这个毒株接种PPV HI抗体阴性的四月龄小猪和怀孕14～23天的后备母猪进行安全性试验,结果无任何异常临床症状、病毒血症和同居感染,母猪分娩正常,初生仔猪在吃初乳前HI抗体阴性。该毒株免疫的小猪、后备母猪和怀孕母猪,完全能抵抗猪细小病毒强毒攻击,攻毒后49天剖杀母猪,结果胎儿正常,胎儿心血HI抗体阴性,取胎儿脏器未分离出病毒,分娩母猪产仔正常,仔猪吃初乳前HI抗体阴性。而对照猪攻毒后产生病毒血症,产下不同组合异常仔,并从死胎儿脏器分离出病毒,健活仔猪吃初乳前能测出HI抗体。从而证明用N株作为弱毒苗能防止由猪细小病毒引起的繁殖障碍性疾病。

STUDIIES ON N STRAIN OF PORCINE PARVOVIRUS-ITS BIOLOGICAI AND IMMUNOLOGICAL CHARACTERISTICS

The N strain of porcine parvovirus was a natural low virulent variant strain, which was isolated from the viscera of a stillborn fetus farrowed by a gilt in Guangxi.Pigs and gilts without HI antibody titres of porcine parvovirus inoculated with the N strain at four-month-old, and 14-23 days gestation respectively. As a result, nothing abnormal was found clinically. There was no viremia and viral excretion. The gilts were normal at parturition. The HI antibody was not detected in any of the piglets before sucking. Pigs gilts and pregnant sows vaccinated with the N strain could resist to the challenge of virulent porcineparvovirus. After challenge, the sows were killed 40 days later, and the fetuses were apparently healthy.The HI antibody of heart blood of these fetuses was negative to porcine parvovirus. The virus was not recovered from the organs of these fetuses. The sows were normal at parturition.The HI antibody of the piglets was negative before sucking. In contrast, the unimmunized control gilts challenged with virulent porcine parvovirus produced viremia, delivered stillbirth and mummified fetuses. The virus was isolated from their organs. The HI antibody could be detected in alive fetuses before sucking. This result suggests a possibility that the N strain of porcine parvovirus can prevent gilts from porcine parvovirus-induced reproductive failure.