PDF(Pubmed)
Abstract：
The highly contagious, immunosuppressive, and cancer-causing Marek\'s disease virus (MDV) infects chickens. The financial costs of Marek\'s disease (MD) are significant for the chicken industry. In this study, a total of 180 samples from chicken farms suspected to be MDV-infected were collected. The chickens were sampled during the period between the months of October 2016 and February 2018 at Dakahlia and Damietta Governorates, Egypt. A total of 36 pooled samples were created. The prepared samples were inoculated into embryonated chicken eggs (ECEs). Indirect fluorescent antibody technique (IFAT) and ICP4 gene-based polymerase chain reaction (PCR) were used for MDV identification. For the genetic characterization of the identified virus, The ICP4 gene sequence was identified and compared with the sequences available from various regions of the world. Furthermore, the genomes of all detected MDVs were screened for the long terminal repeat (LTR) region of reticuloendotheliosis (REV) in their genomes. The results showed that 31 out of 36 pooled samples (86.1%) inoculated into ECEs displayed the characteristic pock lesions. By using IFAT and PCR to identify MDV in ECEs, positive results were found in 27 samples (75%). The Egyptian virus is thought to be genetically closely related to MDVs circulating in Ethiopia, China, and India. REV-LTR was amplified from 6 out of 27 field isolates genomes (22.2 %) while MDV vaccine strains were free from REV-LTR insertion. The integrated REV-LTRs depicted a close genetic relationship with those integrated in fowl poxvirus (FWPV) circulating in Egypt as well as those integrated in FWPVs and MDVs from China, USA, South Africa, and Australia. To the best of our knowledge, this investigation represents the first identification and characterization of REV-LTR insertions in Egyptian MDV field isolates. Given the findings above, additional research in the future seems crucial to determine how the REV-LTR insertions affect MDV pathogenesis, virulence, and insufficient vaccination protection.
摘要：
高度传染性的，免疫抑制,和致癌马立克病病毒（MDV）感染鸡。马立克氏病（MD）的财务成本对养鸡业来说是巨大的。在这项研究中,共从怀疑感染MDV的养鸡场收集了180个样本。这些鸡是在2016年10月至2018年2月期间在Dakahlia和Damietta省采样的，埃及。总共产生了36个汇集的样品。将制备的样品接种到含胚鸡蛋(ECE)中。间接荧光抗体技术（IFAT）和基于ICP4基因的聚合酶链反应（PCR）用于MDV鉴定。为了鉴定病毒的遗传特征，对ICP4基因序列进行了鉴定，并与来自世界各地的序列进行了比较。此外，在所有检测到的MDV的基因组中筛选网状内皮增生病(REV)的长末端重复序列(LTR)区域.结果表明，接种到ECE中的36个合并样品中的31个（86.1％）显示出特征性的麻点病变。通过使用IFAT和PCR鉴定ECE中的MDV，27份样本(75%)呈阳性。埃及病毒被认为与埃塞俄比亚传播的MDV在遗传上密切相关，中国,和印度。从27个野外分离株基因组中的6个扩增REV-LTR(22.2%),而MDV疫苗株没有插入REV-LTR。整合的REV-LTR描绘了与整合在埃及传播的禽类痘病毒（FWPV）以及整合在中国的FWPV和MDV中的紧密遗传关系，美国,南非,和澳大利亚。据我们所知,这项研究代表了埃及MDV田间分离株中REV-LTR插入的首次鉴定和表征。鉴于上述发现，未来的其他研究似乎对于确定REV-LTR插入如何影响MDV发病机制至关重要，毒力,疫苗接种保护不足。
