Alvarez V, Daltabuit-Test M, Arranz J, Leginagoikoa I, Juste R A, Amorena B, de Andrés D, Luján Ll, Badiola J J, Berriatua E
Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Sanidad Animal, 48160-Derio, Vizcaya, Spain.
Res Vet Sci. 2006 Apr;80(2):226-34. doi: 10.1016/j.rvsc.2005.05.008. Epub 2005 Jul 19.
A recent large-scale experimental study showed that bottle-feeding ovine colostrum from seropositive ewes results in high MVV-seroconversion in lambs. In contrast, relatively few lambs that naturally suckled colostrum from seropositive dams seroconverted as a result of it. Furthermore, lambs fed uninfected bovine colostrum readily seroconverted when mixed with ovine-colostrum lambs indicating that horizontal MVV transmission between lambs was efficient. MVV-infection was further investigated in the same samples using two PCR tests targeting sequences in the long-terminal repeats (LTR) and POL MVV genes. PCR-tests confirmed previous serological findings. However, the LTR-PCR was more sensitive and allowed detecting infection earlier than the other tests, including 5-8% of new-born lambs from seropositive dams, providing more evidence that prenatal MVV-infection may be more important than considered. The degree of agreement between PCR and antibody tests in individual samples was low up to 6 months of age and moderate at 10 months-old. Nine percent of lambs were always PCR-negative but seroconverted and 19% of lambs were PCR-positive at least once and did not seroconvert. However, seroconversion was associated with increasing number of times lambs were PCR-positive and ovine colostrum-fed lambs were more frequently PCR-positive than other lambs. The significance of these findings in terms of MVV-infection, epidemiology and control is discussed.
最近一项大规模实验研究表明，用血清反应阳性母羊的初乳人工喂养羔羊会导致羔羊出现较高的梅迪-维斯纳病毒（MVV）血清转化。相比之下，自然吮吸血清反应阳性母羊初乳的羔羊中，因初乳感染而发生血清转化的相对较少。此外，用未感染的牛初乳喂养的羔羊与用羊初乳喂养的羔羊混养时，很容易发生血清转化，这表明羔羊之间的MVV水平传播效率很高。使用针对长末端重复序列（LTR）和POL MVV基因序列的两种聚合酶链反应（PCR）检测方法，对相同样本中的MVV感染情况进行了进一步研究。PCR检测证实了先前的血清学检测结果。然而，LTR-PCR检测更灵敏，比其他检测方法能更早地检测到感染，包括来自血清反应阳性母羊所生的5%-8%的新生羔羊，这提供了更多证据表明产前MVV感染可能比之前认为的更为重要。在6月龄前，个体样本中PCR检测与抗体检测之间的一致性程度较低，10月龄时一致性为中等。9% 的羔羊PCR检测始终为阴性，但发生了血清转化，19% 的羔羊至少有一次PCR检测呈阳性，但未发生血清转化。然而，血清转化与羔羊PCR检测呈阳性的次数增加有关，并且用羊初乳喂养的羔羊比其他羔羊更频繁地出现PCR检测呈阳性。本文讨论了这些研究结果在MVV感染、流行病学和防控方面的意义。
