Burny A, Cleuter Y, Kettmann R, Mammerickx M, Marbaix G, Portetelle D, Van den Broeke A, Willems L, Thomas R
Faculty of Agronomy, Gembloux, Belgium.
Adv Vet Sci Comp Med. 1988;32:149-70. doi: 10.1016/b978-0-12-039232-2.50010-4.
Bovine leukemia virus is the etiological agent of a chronic lymphatic leukemia/lymphoma in cows, sheep, and goats. Infection without neoplastic transformation also was obtained in pigs, rhesus monkeys, chimpanzees, and rabbits, and was observed in capybaras and water buffaloes. Structurally and functionally, BLV is a relative of the human T lymphotropic viruses (HTLV-I and HTLV-II). HTLV-I induces in humans a T cell leukemia, and its type II counterpart has been found in dermatopathic lymphadenopathy, hairy T cell leukemia and prolymphocytic leukemia cases. At variance with HTLV-I, BLV has not been associated with neurological diseases of the degenerative type. BLV, HTLV-I, and HTLV-II show clearcut sequence homologies. The pathology of the BLV-induced disease, most notably, the absence of chronic viremia, a long latency period, and a lack of preferred proviral integration sites in tumors, is similar to that of adult T cell leukemia/lymphoma induced by HTLV-I. The most striking feature of the three naturally transmitted leukemia viruses is the X region located between the env gene and the LTR sequence. The X region contains several overlapping long open reading frames. One of them designated XBL-I encodes a trans-activator function capable of increasing the level of gene expression directed by BLV-LTR and most probably involved in "genetic instability" of BLV-infected cells of the B cell lineage. The genetic instability puts the cell into a context of fragility and ready to move along a number of stages towards full malignancy. Little is known about these events and their causes; we have presented some theoretical possibilities. BLV infection has a worldwide distribution. In temperate climates the virus spreads mostly via iatrogenic transfer of infected lymphocytes. In warm climates and in areas heavily populated by hematophageous insects, there are indications of insect-born propagation of the virus.
牛白血病病毒是牛、绵羊和山羊慢性淋巴细胞白血病/淋巴瘤的病原体。猪、恒河猴、黑猩猩和兔子也出现了无肿瘤转化的感染情况，水豚和水牛中也观察到了这种感染。在结构和功能上，牛白血病病毒是人类嗜T淋巴细胞病毒（HTLV - I和HTLV - II）的亲属。HTLV - I在人类中诱发T细胞白血病，其II型对应物已在皮肤淋巴腺病、毛细胞T细胞白血病和原淋巴细胞白血病病例中发现。与HTLV - I不同，牛白血病病毒与退行性神经疾病无关。牛白血病病毒、HTLV - I和HTLV - II显示出明显的序列同源性。牛白血病病毒诱发疾病的病理学，最显著的是不存在慢性病毒血症、潜伏期长以及肿瘤中缺乏优先的前病毒整合位点，与HTLV - I诱发的成人T细胞白血病/淋巴瘤相似。这三种自然传播的白血病病毒最显著的特征是位于env基因和LTR序列之间的X区域。X区域包含几个重叠的长开放阅读框。其中一个命名为XBL - I的编码一种反式激活功能，能够增加由牛白血病病毒LTR指导的基因表达水平，很可能参与B细胞系牛白血病病毒感染细胞的“遗传不稳定性”。遗传不稳定性使细胞处于脆弱状态，并准备好沿着多个阶段发展为完全恶性肿瘤。关于这些事件及其原因知之甚少；我们提出了一些理论可能性。牛白血病病毒感染在全球范围内分布。在温带气候下，病毒主要通过感染淋巴细胞的医源性转移传播。在温暖气候和吸血昆虫大量繁殖的地区，有迹象表明病毒通过昆虫传播。
