Transmission of Porcine reproductive and respiratory syndrome virus 1 to CrossMark and from vaccinated pigs in a one-to-one model
Transmission of Porcine reproductive and respiratory syndrome virus 1 to CrossMark and from vaccinated pigs in a one-to-one model
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DOI：
10.1016/j.vetmic.2016.12.012
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发表时间：
2017-03-01
影响因子：
3.3
通讯作者：
Mateu, E.
中科院分区：
文献类型：
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作者：
Pileri, E.;Gibert, E.;Mateu, E.
本研究以一对一模型研究了猪繁殖与呼吸综合征病毒(PRRSV)I型通过接触传播给接种疫苗和未接种疫苗的猪，以及从接种过疫苗的感染猪到其他接种过的猪。试验首先将断奶仔猪随机分为两组：V组24头和U组26头。用市售PRRSV减毒活疫苗免疫V猪，将U代猪作为未接种的对照。28天后，将6头U猪分离并分配到单独的盒子中。其余20头U猪鼻腔接种PRRSV 3267分离株(即日起定为种猪(S))，48h后分箱接种，与V、U猪按1：1混合(第一接触阶段)，得到6对S：U和14对S：V。一旦一头V猪因为接触了S而被检测到是病毒携带者，被感染的V猪(从现在起被指定为V-INF)被转移到新的围栏(检测后24小时)，在那里它在第二次接触阶段与新的V猪(被指定为V2)相遇。在第一次接触阶段，猪最多保持21天，第二次接触阶段，最长暴露时间为14天。当两头V猪与相应的V2猪被重新安置并被移走时，两头V猪的疫苗病毒检测呈阳性(>；99.5%相似)；因此，最终只有12头VIA被考虑。所有暴露于S动物的V猪(12/12)都被感染，尽管首次发现病毒血症发生在13.6+/-3.6d，比U组晚一周(p<；0.05)。此外，VIA组病毒血症持续时间比U组短，分别为5.5±4.3天和12.5±2.7天。VIA组表现出显著的个体差异：8只动物的病毒期为5天或更短(3.0+/-1.4)，其余4只动物的病毒期超过1周(10.8+/-2.9)。在第二次接触中，有7/8例(87.5%)从V、f猪传播到V2猪。V2病毒血症的平均持续时间为4.8+/-3.4，并再次观察到两种不同的模式：2只动物的病毒血症持续时间为9-10天，其余的平均为3.0+/-1.4天(范围：2-5天)。与U组相比，在病毒血症开始后至少9天内，接种Vinf组和V2组的口腔分泌物中的PRRSV排泄量显著减少，V2组的排泄量甚至显著低于Vim组(p<；0.05)。我们的实验设计再现了评估疫苗接种效果的最坏情况，在这种情况下，它在减缓PRRSV传播和降低全球病毒载量，特别是口腔脱落方面仍然有效。2016由爱思唯尔出版。
The present study examined transmission by contact of Porcine reproductive and respiratory syndrome virus (PRRSV) I in a one-to-one model to vaccinated and unvaccinated pigs and from vaccinated infected pigs to other vaccinated pigs. The experiment started by randomly assigning weaned pigs to groups V n = 24) and U (n = 26). V pigs were vaccinated with a commercial live attenuated PRRSV vaccine and the U animals were kept as unvaccinated controls. Twenty-eight days later, 6 U pigs were separated and allocated in individual boxes. The remaining 20 U pigs were intranasally inoculated with PRRSV isolate 3267 (from now on designated as seeder (S) pigs) and 48 h later were distributed in boxes where they were commingled with either V or U pigs in 1:1 groups (first contact phase), resulting in 6 S:U and 14 S:V pairs. As soon as a V pig was detected to be viremic because of contact with a S, the infected V (from now on designated as V-inf) was transferred (< 24 h after detection) to a new pen where it was comingled with a new V pig (designated as V2) in a second contact phase. For the first contact phase, pigs were maintained 21 days at maximum and for the second contact phase the maximum exposure period was 14 days. Two V pigs tested positive for the vaccine virus (> 99.5% similarity) when they were relocated with the corresponding V2 pigs and they were removed; thus, only 12 Via were finally considered. All V pigs (12/ 12) exposed to S animals became infected although the first detection of viremia occurred at 13.6 +/- 3.6 days, one week later than in U (p < 0.05). Also, duration of viremia was shorter for Via compared to U, (5.5 +/- 4.3 days versus 12.5 +/- 2.7 days). The Via group showed remarkable individual variability: eight animals had a viremic period of 5 or less days (3.0 +/- 1.4) while the remaining four had a longer viremic period of more than one week (10.8 +/- 2.9). This situation was not observed in U. In the second contact phase, transmission from V, f to V2 pigs occurred in 7/8 cases (87.5%). The mean duration of viremia for V2 was 4.8 +/- 3.4 and two different patterns were again observed: two animals had viremias of 9-10 days and the rest averaged 3.0 +/- 1.4 days (range: 2-5 days). Vaccinated groups Vinf and V2 had a significantly lower PRRSV shedding in oral fluids for at least the first 9 days after the onset of the viremia compared to U, and shedding for V2 was even significantly lower (p < 0.05) than shedding for Vim. Our experimental design reproduced the worst -case scenario for evaluating the effect of vaccination and, under such conditions; it was still efficacious in slowering PRRSV transmission and decreasing the global viral load and particularly oral shedding. 2016 Published by Elsevier B.V.