Bonzon C, Fan H
Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, California 92697, USA.
J Virol. 1999 Mar;73(3):2434-41. doi: 10.1128/JVI.73.3.2434-2441.1999.
Moloney murine leukemia virus (M-MuLV) is a replication-competent, simple retrovirus that induces T-cell lymphoma with a mean latency of 3 to 4 months. During the preleukemic period (4 to 10 weeks postinoculation) a marked decrease in thymic size is apparent for M-MuLV-inoculated mice in comparison to age-matched uninoculated mice. We were interested in studying whether the thymic regression was due to an increased rate of thymocyte apoptosis in the thymi of M-MuLV-inoculated mice. Neonatal NIH/Swiss mice were inoculated subcutaneously (s.c.) with wild-type M-MuLV (approximately 10(5) XC PFU). Mice were sacrificed at 4 to 11 weeks postinoculation. Thymic single-cell suspensions were prepared and tested for apoptosis by two-parameter flow cytometry. Indications of apoptosis included changes in cell size and staining with 7-aminoactinomycin D or annexin V. The levels of thymocyte apoptosis were significantly higher in M-MuLV-inoculated mice than in uninoculated control animals, and the levels of apoptosis were correlated with thymic atrophy. To test the relevance of enhanced thymocyte apoptosis to leukemogenesis, mice were inoculated with the Mo+PyF101 enhancer variant of M-MuLV. When inoculated intraperitoneally, a route that results in wild-type M-MuLV leukemogenesis, mice displayed levels of enhanced thymocyte apoptosis comparable to those seen with wild-type M-MuLV. However, in mice inoculated s.c., a route that results in attenuated leukemogenesis, significantly lower levels of apoptosis were observed. This supported a role for higher levels of thymocyte apoptosis in M-MuLV leukemogenesis. To examine the possible role of mink cell focus-forming (MCF) recombinant virus in raising levels of thymocyte apoptosis, MCF-specific focal immunofluorescence assays were performed on thymocytes from preleukemic mice inoculated with M-MuLV and Mo+PyF101 M-MuLV. The results indicated that infection of thymocytes by MCF virus recombinants is not required for the increased level of apoptosis and thymic atrophy.
莫洛尼鼠白血病病毒（M-MuLV）是一种具有复制能力的简单逆转录病毒，可诱发T细胞淋巴瘤，平均潜伏期为3至4个月。在白血病前期（接种后4至10周），与年龄匹配的未接种小鼠相比，接种M-MuLV的小鼠胸腺大小明显减小。我们感兴趣的是研究胸腺退化是否是由于接种M-MuLV的小鼠胸腺中胸腺细胞凋亡率增加所致。新生的NIH/瑞士小鼠皮下接种野生型M-MuLV（约10⁵XC空斑形成单位）。在接种后4至11周处死小鼠。制备胸腺单细胞悬液，并通过双参数流式细胞术检测凋亡情况。凋亡的指标包括细胞大小的变化以及用7-氨基放线菌素D或膜联蛋白V染色。接种M-MuLV的小鼠胸腺细胞凋亡水平显著高于未接种的对照动物，且凋亡水平与胸腺萎缩相关。为了测试增强的胸腺细胞凋亡与白血病发生的相关性，给小鼠接种M-MuLV的Mo+PyF101增强子变体。当通过腹腔内接种（一种导致野生型M-MuLV白血病发生的途径）时，小鼠表现出与野生型M-MuLV相当的增强的胸腺细胞凋亡水平。然而，在皮下接种（一种导致白血病发生减弱的途径）的小鼠中，观察到凋亡水平明显较低。这支持了较高水平的胸腺细胞凋亡在M-MuLV白血病发生中的作用。为了研究貂细胞集落形成（MCF）重组病毒在提高胸腺细胞凋亡水平方面的可能作用，对接种M-MuLV和Mo+PyF101 M-MuLV的白血病前期小鼠的胸腺细胞进行了MCF特异性灶性免疫荧光测定。结果表明，MCF病毒重组体感染胸腺细胞并非凋亡水平升高和胸腺萎缩所必需。
