Enzootic bovine leukosis in a 21-month-old Japanese Black cow with high susceptibility
Enzootic bovine leukosis in a 21-month-old Japanese Black cow with high susceptibility
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DOI：
10.1177/10406387221102123
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发表时间：
2022-06-10
影响因子：
1.5
通讯作者：
Inokuma, Hisashi
中科院分区：
文献类型：
--
作者：
Maezawa, Masaki;Sakaguchi, Kana;Inokuma, Hisashi
一头21个月大的日本黑肉牛下颌和颈浅淋巴结肿大。颈浅淋巴结的细针抽吸细胞学检查显示存在有丝分裂的大淋巴母细胞。牛白血病病毒（BLV）原病毒载量相对较高，对整个BLV基因组的系统发育分析将BLV毒株归类为具有高病毒复制活性的毒株。牛白细胞抗原基因的基因分型表明，该牛易患地方性牛白血病（EBL）。骨形态发生蛋白 6 (BMP6) 基因启动子区域高度甲基化。分别通过 B 细胞的克隆性测试和反向 PCR 测定检测 B 细胞的单克隆增殖和 BLV 原病毒在牛基因组中的单克隆整合。尸检时，观察到 L5-6 椎骨淋巴结普遍肿胀，肿瘤组织侵入椎管。组织学分析显示大圆形肿瘤细胞弥漫性增殖，BLA36 呈阳性，CD3 呈阴性。根据这些发现，这头牛被明确诊断为 EBL。在我们的病例中，高致病性 BLV 菌株的感染、BoLA-DRB3 等位基因的易感性以及 BMP6 基因的高甲基化可能导致了 EBL 的发生。
A 21-mo-old Japanese Black beef cow had swollen mandibular and superficial cervical lymph nodes. Fine-needle aspiration cytology of the superficial cervical lymph node revealed large lymphoblasts with mitoses present. The bovine leukemia virus (BLV) proviral load was relatively high, and phylogenetic analysis of the whole BLV genome classified the BLV strain as one with high viral replication activity. Genotyping of bovine leukocyte antigen genes indicated that the cow was susceptible to enzootic bovine leukosis (EBL). The bone morphogenetic protein 6 (BMP6) gene promoter region was hypermethylated. Monoclonal proliferation of B cells and monoclonal integration of the BLV provirus in the bovine genome were detected by a clonality test of B cells and an inverse PCR assay, respectively. At autopsy, generalized swelling of lymph nodes and spinal canal invasion by tumor tissue at vertebrae L5-6 were observed. Histologic analysis revealed diffuse proliferation of large round neoplastic cells that were positive for BLA36 and negative for CD3. The cow was definitively diagnosed with EBL based on these findings. Infection with a highly pathogenic strain of BLV, susceptibility of the BoLA-DRB3 alleles, and hypermethylation of the BMP6 gene may have contributed to the development of EBL in our case.