Epidemiology and Risk Analysis Applied to Veterinary Sciences, Department of Infectious and Parasitic Diseases, Faculty of Veterinary Medicine, University of Liège, 4000 Liège, Belgium.
Vet J. 2011 Jan;187(1):72-80. doi: 10.1016/j.tvjl.2009.11.012. Epub 2010 Jan 12.
Infection with bluetongue virus serotype (BTV)-8 occurred in ruminants in 2006 in Central-Western Europe. The trans-placental passage of this virus has been demonstrated in naturally- and experimentally-infected cattle and in experimentally-infected sheep. Trans-placental transmission is potentially important in the 'over-wintering' of this virus and its subsequent impact on reproductive performance. This epidemiological study was carried out on a sheep flock in Belgium that had experienced a severe outbreak of BTV-8 infection, and where the seroprevalence had increased from 1.3% to 88% between January and November 2007. In total, 476 lambs and 26 aborted fetuses from 300 ewes, lambing at four distinct time periods, were investigated between November 2007 and May 2008. The following evidence suggested that BTV-8 infection occurred in utero: (1) positive PCR results from splenic tissue from aborted fetuses (n=4); (2) fetal malformations suggestive of BTV infection (n=10); (3) positive PCR results from red blood cells in-lambs (n=7), and (4) the presence of antibody at birth in viable lambs prior to the intake of colostrum (n=9). The evidence provided by this investigation strongly suggests that trans-placental BTV-8 infection occurs in naturally-infected sheep and the impact of infection on the reproductive performance of such a naïve flock was considerable, with up to 25% of ewes aborting and with flock fertility reduced by 50%. The contribution of in utero-infected lambs to the over-wintering of BTV appears limited.
2006 年，蓝舌病病毒血清型 8（BTV-8）在中欧的反刍动物中感染。该病毒已在自然感染和实验感染的牛以及实验感染的绵羊中证实存在胎盘传播。胎盘传播在该病毒的“越冬”及其随后对繁殖性能的影响中具有重要意义。本研究在比利时的一个绵羊群中进行，该羊群曾经历过严重的 BTV-8 感染爆发，2007 年 1 月至 11 月间血清阳性率从 1.3%上升至 88%。共检测了 300 只产仔母羊所产的 476 只羔羊和 26 只流产胎儿，这些母羊分四个不同时间段产仔。2007 年 11 月至 2008 年 5 月间，有以下证据表明 BTV-8 感染发生在子宫内：（1）4 例流产胎儿脾脏组织的 PCR 结果阳性；（2）10 例胎儿畸形提示 BTV 感染；（3）7 例羔羊红细胞的 PCR 结果阳性；（4）在摄入初乳之前，存活羔羊在出生时就存在抗体（9 例）。本研究提供的证据强烈表明，在自然感染的绵羊中存在 BTV-8 的胎盘感染，感染对如此原始的羊群的繁殖性能造成了巨大影响，多达 25%的母羊流产，羊群繁殖力降低了 50%。子宫内感染的羔羊对 BTV 的越冬贡献似乎有限。
