Newby T J, Carter D P, Yoon K-J, Jackwood M W, Hawkins P A
Animal Health Group, Pfizer Inc, Lincoln, Nebraska, USA.
J Vet Sci. 2002 Jun;3(2):61-6.
A nonclinical study was conducted to characterize the replication behavior of a modified live gE-deleted pseudorabies virus (PRV MS+1) in swine and potential for reversion to virulence after animal passages. Two to 3 week-old weaned pigs, negative for PRV, were maintained in isolation and challenged by intranasal instillation. For the first passage, 6 pigs were given 1 mL of PRV MS+1 (10(7.3)TCID(50)/mL) and 2 were necropsied at 3, 4 and 5 days post-inoculation (PI). Brain and secondary lymphoid tissues were collected, homogenized and the supernatants individually pooled for virus isolation, and PRV was recovered from each sample. No clinical signs of PRV infection were observed, but each pig had a nasal swab suspect or positive for PRV. For the second passage, 5 pigs were given 1 mL of the homogenate of mixed tissues from 1 animal in the previous passage (PRV at 10(1.9) TCID(50)/mL). At 5 days PI, all pigs were necropsied, and PRV was not recovered from their tissue homogenates or nasal swabs, and no clinical signs were observed. During a second attempt at a second passage, tissue homogenates from all pigs in the first passage (PRV at approximately 10(1.7)TCID50(50)/mL) were pooled and used to inoculate 15 pigs with 2 mL for 3 consecutive days. Ten pigs were monitored for clinical signs and seroconversion through 21 days PI, and 5 pigs were necropsied at 5 days PI. No clinical signs or PRV antibodies were detected in the 10 monitored pigs, and no PRV was recovered from the homogenates or nasal swabs of the 5 necropsied pigs. Thus, no evidence of reversion to virulence was demonstrated in pigs given the attenuated PRV.
进行了一项非临床研究，以表征一种缺失糖蛋白E的改良活伪狂犬病病毒（PRV MS+1）在猪体内的复制行为以及在动物传代后恢复毒力的可能性。将2至3周龄、PRV检测呈阴性的断奶仔猪单独饲养，并通过滴鼻法进行攻毒。在首次传代时，给6头猪滴鼻接种1 mL PRV MS+1（10(7.3)TCID(50)/mL），并在接种后第3、4和5天对2头猪进行剖检。采集脑和二级淋巴组织，匀浆后将上清液单独合并用于病毒分离，每个样本均分离出了PRV。未观察到PRV感染的临床症状，但每头猪的鼻拭子检测均怀疑为PRV阳性或呈阳性。在第二次传代时，给5头猪滴鼻接种1 mL来自上一代1头动物的混合组织匀浆（PRV含量为10(1.9) TCID(50)/mL）。在接种后第5天，对所有猪进行剖检，未从其组织匀浆或鼻拭子中分离出PRV，也未观察到临床症状。在第二次传代的第二次尝试中，将第一代所有猪的组织匀浆（PRV含量约为10(1.7)TCID50(50)/mL）合并，连续3天给15头猪每头接种2 mL。对10头猪在接种后21天内监测临床症状和血清转化情况，在接种后第5天对5头猪进行剖检。在10头监测猪中未检测到临床症状或PRV抗体，在5头剖检猪的匀浆或鼻拭子中也未分离出PRV。因此，在接种减毒PRV的猪中未证明有恢复毒力的迹象。
