Sherr C J, Fedele L A, Donner L, Turek L P
J Virol. 1979 Dec;32(3):860-75. doi: 10.1128/JVI.32.3.860-875.1979.
Extrachromosomal DNA purified from mink cells acutely infected with the Snyder-Theilen strain of feline sarcoma virus (FeSV) was digested with restriction endonucleases, and the DNA fragments were electrophoretically separated, transferred to a solid substrate, and hybridized with radiolabeled DNA transcripts complementary to different portions of the FeSV RNA genome. Major DNA species 8.4 and 5.0 kilobase pairs (kbp) long represent the linear, unintegrated proviruses of Snyder-Theilen feline leukemia virus and FeSV, respectively. Transfection experiments performed with electroeluted DNAs showed that the 8.4-kbp form led to the production of replicating nontransforming virus in mink and cat cells; in contrast, the 5.0-kbp DNA produced helper virus-independent foci of transformation in mouse NIH/3T3 cells and helper virus-dependent foci in mink cells at an efficiency comparable to that obtained with unfractionated extrachromosomal DNA. Sites of restriction endonuclease cleavage for six enzymes were oriented with respect to one another within the FeSV provirus. EcoRI recognized cleavage sites at 0.3 to 0.4 kbp from each terminus of FeSV DNA, reducing the 5.0-kbp DNA to molecules 4.3 kbp long; this enzyme excised a large internal proviral DNA fragment of corresponding size from the DNA of FeSV-transformed mink nonproducer cells. By using DNA transcripts complementary to different portions of the FeSV genome, sarcoma-specific sequences (the FeSV src gene) were positioned within 2.1 and 3.4 kbp from the 5' end of the proviral DNA with respect to the viral RNA genome. The src gene is flanked at both ends by sequences shared in common with feline leukemia virus. The localization of src sequences to this region suggests that a portion of an FeSV polyprotein which contains feline oncornavirus-associated cell membrane antigen (FOCMA-S) is the major product of this gene.
从急性感染了 Snyder - Theilen 株猫肉瘤病毒（FeSV）的水貂细胞中纯化出的染色体外 DNA，用限制性内切酶进行消化，DNA 片段经电泳分离后转移到固体基质上，并与与 FeSV RNA 基因组不同部分互补的放射性标记 DNA 转录本杂交。长度为 8.4 和 5.0 千碱基对（kbp）的主要 DNA 种类分别代表 Snyder - Theilen 猫白血病病毒和 FeSV 的线性、未整合的前病毒。用电洗脱 DNA 进行的转染实验表明，8.4 - kbp 形式的 DNA 在水貂和猫细胞中导致产生可复制的非转化病毒；相比之下，5.0 - kbp DNA 在小鼠 NIH/3T3 细胞中产生不依赖辅助病毒的转化灶，在水貂细胞中产生依赖辅助病毒的转化灶，其效率与未分级的染色体外 DNA 相当。在 FeSV 前病毒中，六种酶的限制性内切酶切割位点相互之间有特定的排列方向。EcoRI 在距 FeSV DNA 每个末端 0.3 至 0.4 kbp 处识别切割位点，将 5.0 - kbp DNA 切割成 4.3 kbp 长的分子；该酶从 FeSV 转化的水貂非生产细胞的 DNA 中切除了一个相应大小的大的内部前病毒 DNA 片段。通过使用与 FeSV 基因组不同部分互补的 DNA 转录本，肉瘤特异性序列（FeSV src 基因）相对于病毒 RNA 基因组定位在距前病毒 DNA 5' 端 2.1 和 3.4 kbp 范围内。src 基因两端侧翼是与猫白血病病毒共有的序列。src 序列定位于该区域表明，含有猫肿瘤病毒相关细胞膜抗原（FOCMA - S）的 FeSV 多蛋白的一部分是该基因的主要产物。
