Yanagawa S, Murakami A, Hoshino M, Tanaka H
Department of Viral Oncology, Kyoto University, Japan.
J Virol. 1988 Apr;62(4):1235-42. doi: 10.1128/JVI.62.4.1235-1242.1988.
A 2.7-kilobase (kb) cDNA sequence complementary to Suncus murinus mammary tumor virus (Sm-MTV) genomic RNA [corrected] was prepared using purified virions produced by the Sm-MT cell line, which had been established from a spontaneous mammary tumor of S. murinus. It was found, by using this cDNA in Southern hybridization experiments, that Sm-MTV was endogenous to this animal and that some 50 copies of endogenous provirus were present per haploid cellular genome. In addition, a proviral Sm-MTV DNA sequence, 9.4 kb long (Sm-P-MTV10), was cloned from a Sm-MT cell genomic library, and its long terminal repeat was found to be 720 base pairs (bp) long, with the U3.R and U5 regions 574 and 146 bp long, respectively. The boundary between U3 and R was not determined with certainty, though in the cDNA, the U3 and R regions were 462 and 105 bp long, respectively. The overall homology between the U3.R regions in the cDNA and Sm-P-MTV was 75%. These two DNAs differed in such transcription regulatory signals as CCAAT and TATAA, the first being missing from the cDNA. Nevertheless, chloramphenicol acetyltransferase assays showed that the long terminal repeats of the cDNA and the Sm-P-MTV were transcriptionally active but not steroid hormone responsive. Like Mason-Pfizer monkey virus, Sm-MTV used tRNA(1,2Lys) as a primer for reverse transcription. In addition, the immunosuppressive peptide sequence common to many retroviruses was found in the env region of Sm-MTV. In these two points, Sm-MTV differed from mouse MTV.
利用从褐家鼠自发乳腺肿瘤建立的Sm-MT细胞系产生的纯化病毒粒子，制备了一段与褐家鼠乳腺肿瘤病毒（Sm-MTV）基因组RNA互补的2.7千碱基（kb）cDNA序列[已校正]。通过在Southern杂交实验中使用该cDNA发现，Sm-MTV是这种动物的内源性病毒，并且每个单倍体细胞基因组中存在约50个内源性前病毒拷贝。此外，从Sm-MT细胞基因组文库中克隆了一个9.4 kb长的前病毒Sm-MTV DNA序列（Sm-P-MTV10），发现其长末端重复序列长720个碱基对（bp），U3.R和U5区域分别长574和146 bp。虽然在cDNA中U3和R区域分别长462和105 bp，但U3和R之间的边界尚未确定。cDNA和Sm-P-MTV中U3.R区域之间的总体同源性为75%。这两个DNA在转录调控信号如CCAAT和TATAA方面有所不同，第一个信号在cDNA中缺失。然而，氯霉素乙酰转移酶分析表明，cDNA和Sm-P-MTV的长末端重复序列具有转录活性，但对类固醇激素无反应。与猴泡沫病毒一样，Sm-MTV使用tRNA(1,2Lys)作为逆转录引物。此外，在Sm-MTV的env区域发现了许多逆转录病毒共有的免疫抑制肽序列。在这两点上，Sm-MTV与小鼠MTV不同。
