CHARACTERIZATION OF ENDOGENOUS ECOTROPIC AND XENOTROPIC MURINE LEUKEMIA VIRUSES

水貂细胞病灶形成（MCF）病毒是双嗜性鼠病毒 白血病病毒（MuLV）已经从白血病细胞中分离出来， 小鼠组织。 这些病毒被分为两类 基于它们加速胸腺细胞增殖的能力 AKR小鼠的淋巴瘤。 这两类MCF病毒都是通过以下方式产生的： 涉及亲嗜性MuLV和内源性MCF-7的重组 相关的env序列。 致白血病MCF MuLV（1类） 在胸腺中有效复制，而非白血病原性 （II类）在胸腺中生长不良。 长末端重复序列 已经被证明与组织特异性和疾病有关 与致白血病MuLV相关的诱导;此外，序列 存在于gag、pol或env区域的，已被证明是 表达最大致白血病性所必需的。 研究 涉及病毒性白血病发生的MCF-MuLV序列， 分子克隆DNA的白血病MCF-13和非- 获得白血病原性MCF-111 A MuLV，并将核苷酸 测定LTR、3 ′ pol和5 ′ env区的序列。 的 比较分析的结果表明，在LTR的差异 和MCF-13和MCF-111 A MuLV DNA之间的3 ′ pol区。 与MCF-13相关的LTR与 存在于异嗜性MuLV中，而MCF-7的LTR序列 111 A与亲嗜性前病毒LTR除了1 bp外是相同的。 一个12 bp的核苷酸片段，具有致白血病MCF的特征 MuLV在MCF-13的3' pol区域中存在，但缺乏 在MCF-11 A中。 未发现明显的序列差异 MCF-13和MCF-111 A MuLV DNA在env区之间。 这些结果表明，MCF-13的致白血病潜力 可以存在于LTR和3' pol序列中。

Mink cells focus forming (MCF) viruses are dualtropic murine leukemia viruses (MuLVs) which have been isolated from leukemic mouse tissue. These viruses have been divided into two classes based on their ability to accelerate the onset of thymic lymphomas in AKR mice. Both classes of MCF viruses arise by recombination involving ecotropic MuLV and endogenous MCF- related env sequences. Leukemogenic MCF MuLVs (class 1) replicate efficiently in the thymus whereas the non-leukemogenic (class II) grow poorly in the thymus. Long terminal repeats (LTRs) have been shown to be involved in tissue-specificity and disease induction associated with leukemogenic MuLVs; also, sequences present in the gag, pol, or env regions, have been shown to be necessary for expression of maximum leukemogenicity. To study the sequences of MCF-MuLVs involved in viral leukemogenesis, molecularly cloned DNAs of leukemogenic MCF-13 and non- leukemogenic MCF-111A MuLVs were obtained and the nucleotide sequences of the LTRs, 3' pol and 5' env regions determined. The results of comparative analysis indicated differences in the LTR and 3' pol regions between MCF-13 and MCF-111A MuLV DNAs. The LTR associated with MCF-13 was closely related to that present in xenotropic MuLVs, whereas the LTR sequence of MCF- 111A was identical except for 1 bp to the ecotropic proviral LTR. A 12 bp nucleotide stretch, characteristic of leukemogenic MCF MuLVs, was present in MCF-13 in the 3' pol region but was lacking in MCF-11A. No significant sequence divergence was seen between MCF-13 and MCF-111A MuLV DNAs in the env region. These results suggest that the leukemogenic potential of MCF-13 may reside in LTR and 3' pol sequences.