Shin J, Torrison J, Choi C S, Gonzalez S M, Crabo B G, Molitor T W
Department of Clinical Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA.
Vet Microbiol. 1997 Apr;55(1-4):337-46. doi: 10.1016/s0378-1135(96)01336-3.
A major concern exists on transmission of porcine reproductive and respiratory syndrome virus (PRRSV) via semen and effect of vaccination on PRRSV shedding in semen. Recent reports suggest that the virus can be transmitted by semen from boars infected experimentally or from natural sources. Seminal shedding, viremia, and changes in semen quality in boars with or without vaccination were examined. Nine boars were divided into three groups (three boars/group). Group I boars were vaccinated with 2 ml of RespPRRS vaccine (NOBL Laboratory) intramusculary and groups II and III were non-vaccinated. At 28 post-vaccination study days, group I and group II boars were challenged with virulent PRRSV VR-2332 at 2 ml of 10(4.0) TCID50 per boar intranasally. Group III served as non-vaccinated and non-challenged control. Semen and serum samples were collected from -9 pre-vaccination study days to 85 post-challenge study days and tested for the presence of PRRSV by virus isolation and reverse transcription-nested polymerase chain reaction (RT-nPCR). Prior to detection of PRRSV RNA from samples, conditions for RT-nPCR were optimized. Two primer sets, an external and an internal, were selected for RT-nPCR. The first round of PCR using an external primer set could detect 10 TCID50 of PRRSV/reaction. However, nested PCR could detect as little as 0.01 TCID50 of PRRSV/reaction. PRRS vaccine virus was not isolated from vaccinated pigs, but the vaccine virus RNA was detected from three boars, at day 6 to 15, 9 to 12, and 15 to 21 post-vaccination by RT-nPCR. Following challenge, two of non-vaccinated/challenged boars shed virus into semen up to 50 and 57 days post-challenge, respectively. The group I vaccinated boars did not shed virus into semen after challenge. The non-vaccinated/challenged group featured sperm abnormalities in the form of significantly increased incidence of proximal droplets and abnormal tails at 36-50 days post-challenge. The latter defect was observed to increase similarly in vaccinated/challenged boars as well.
猪繁殖与呼吸综合征病毒（PRRSV）通过精液传播以及疫苗接种对精液中PRRSV排出的影响是一个主要关注点。最近的报告表明，该病毒可通过实验感染的公猪或自然感染源的精液传播。研究了接种或未接种疫苗的公猪的精液排毒、病毒血症及精液质量变化。将9头公猪分为三组（每组3头）。第I组公猪肌肉注射2毫升RespPRRS疫苗（NOBL实验室），第II组和第III组未接种疫苗。在接种疫苗后第28天的研究期，第I组和第II组公猪经鼻接种每头2毫升含10(4.0) TCID50的强毒PRRSV VR - 2332。第III组作为未接种疫苗且未受挑战的对照。从接种疫苗前9天至挑战后85天采集精液和血清样本，通过病毒分离和逆转录巢式聚合酶链反应（RT - nPCR）检测PRRSV的存在。在从样本中检测PRRSV RNA之前，对RT - nPCR条件进行了优化。选择了两组引物，一组外部引物和一组内部引物用于RT - nPCR。使用外部引物组进行的第一轮PCR可检测到10 TCID50的PRRSV/反应。然而，巢式PCR可检测到低至0.01 TCID50的PRRSV/反应。未从接种疫苗的猪中分离出PRRS疫苗病毒，但通过RT - nPCR在接种疫苗后第6至15天、第9至12天和第15至21天从三头公猪中检测到疫苗病毒RNA。挑战后，两头未接种疫苗/受挑战的公猪分别在挑战后50天和57天向精液中排毒。第I组接种疫苗的公猪在挑战后未向精液中排毒。未接种疫苗/受挑战组在挑战后36 - 50天出现精子异常，表现为近端液滴发生率显著增加和尾部异常。在接种疫苗/受挑战的公猪中也观察到后者的缺陷有类似增加。
