Grupo de Investigación Centauro, Universidad de Antioquia, Medellín, Colombia.
Grupo de Investigación CIBAV, Universidad de Antioquia, Medellín, Colombia.
Poult Sci. 2017 Jun 1;96(6):1598-1608. doi: 10.3382/ps/pew464.
Marek's disease (MD) is a lymphoproliferative disease caused by an Alphaherpesvirus, genus Mardivirus, serotype 1 (Gallid Herpesvirus 2, GaHV-2) that includes all known pathogenic strains. In addition to Marek's disease virus (MDV) serotype 1, the genus includes 2 distinct nonpathogenic serotypes: serotype 2 (GaHV-3) and serotype 3 (Meleagridis Herpesvirus 1, MeHV-1) which are used in commercially available vaccines against MD. As a result of vaccination, clinical signs are not commonly observed, and new cases are usually associated with emerging variant strains against which the vaccines are less effective. In this study, a commercial layer farm showing clinical signs compatible with MDV infection was evaluated. Histological lesions and positive immunohistochemistry in the sciatic nerve and thymus were compatible with cytolytic phase of MD. GaHV-2, GaHV-3 and MeHV-1 were identified by PCR and qPCR in blood samples from 17 birds with suspected MD. Analysis of the Meq gene of the Colombian GaHV-2 isolate revealed a 99% sequence identity with Asian strains, and in the phylogenetic analysis clustered with vv+ MDV. The analysis of amino acid alignments demonstrated an interruption of the proline rich region in P176A, P217A and P233L positions, which are generally associated with vv+ strains. Some of these changes, such as P233L and L258S positions have not been reported previously. In addition, primary cell cultures inoculated with lymphocytes isolated from the spleen showed typical cytopathic effect of GaHV-2 at 5 d post infection. Based on the molecular analysis, the results from this study indicate the presence of vv+ MDV infection in commercial birds for the first time in Colombia. It is recommended to perform further assays in order to demonstrate the pathotype characteristics in vivo.
马立克氏病（MD）是一种由α疱疹病毒引起的淋巴组织增生性疾病，属 Mardivirus 属，血清型 1（禽疱疹病毒 2，GaHV-2），包括所有已知的致病性毒株。除了马立克氏病病毒（MDV）血清型 1 外，该属还包括 2 种不同的非致病性血清型：血清型 2（GaHV-3）和血清型 3（火鸡疱疹病毒 1，MeHV-1），这两种病毒都被用于针对 MD 的商业可用疫苗。由于接种疫苗，通常不会观察到临床症状，并且新发病例通常与疫苗效果较差的新型变异株有关。在这项研究中，对一个表现出与 MDV 感染相符的临床症状的商业蛋鸡养殖场进行了评估。坐骨神经和胸腺的组织学病变和阳性免疫组织化学染色与 MD 的细胞溶解阶段相符。通过 PCR 和 qPCR 在 17 只疑似 MD 的鸡的血液样本中鉴定出 GaHV-2、GaHV-3 和 MeHV-1。对哥伦比亚 GaHV-2 分离株的 Meq 基因分析显示，其与亚洲株的序列同一性为 99%，在系统进化分析中与 vv+ MDV 聚类。对氨基酸序列比对的分析表明，在 P176A、P217A 和 P233L 位置的脯氨酸丰富区发生了中断，这些位置通常与 vv+ 株有关。其中一些变化，如 P233L 和 L258S 位置，以前尚未报道过。此外，用从脾脏分离的淋巴细胞接种的原代细胞培养物在感染后 5 天显示出典型的 GaHV-2 细胞病变效应。基于分子分析，本研究的结果首次表明 vv+MDV 感染在哥伦比亚的商业禽类中存在。建议进一步进行检测，以证明体内的病原型特征。
