Smith H S, Gelb L D, Martin M A
Proc Natl Acad Sci U S A. 1972 Jan;69(1):152-6. doi: 10.1073/pnas.69.1.152.
Infection with simian virus 40 is known to induce many cells to synthesize DNA and to divide in a medium lacking serum protein growth factor(s) that is essential for growth of uninfected cells (factor-free medium). Cells infected under these conditions then go through several rounds of division, since colonies containing more than 100 cells are formed. Many of these colonies are abortively transformed since, upon subsequent passage of the cells in standard medium, they can no longer grow in factor-free medium and show no other properties of viral transformation. We have examined these abortively transformed cells for the presence of simian virus 40 DNA sequences. Of the three clones tested, two were found to contain viral genetic material despite the fact that they were phenotypically normal. The number of simian virus 40 genome equivalents present was determined by measurement of DNA reassociation kinetics on hydroxyapatite. Two of the abortively transformed lines contained approximately five viral genome equivalents per diploid cell, while the DNA from a third abortive transformant was indistinguishable from that of uninfected BALB/3T3 cells. A standard simian virus 40 transformant, isolated under similar conditions, contained two copies of the viral genome per cell. The abortive transformants also appear to contain the entire viral genome rather than multiple partial copies. Subclones of one abortively transformed line containing five copies per cell had 2.7-10 copies of viral genetic material per diploid cell.
已知感染猿猴病毒40会诱导许多细胞在缺乏血清蛋白生长因子（未感染细胞生长所必需的因子，即无因子培养基）的培养基中合成DNA并进行分裂。在这些条件下感染的细胞随后会经历几轮分裂，因为会形成含有100多个细胞的集落。这些集落中的许多都发生了流产性转化，因为在随后将细胞传代至标准培养基中时，它们无法再在无因子培养基中生长，并且没有显示出病毒转化的其他特性。我们检查了这些流产性转化细胞中是否存在猿猴病毒40 DNA序列。在所测试的三个克隆中，尽管它们在表型上是正常的，但发现其中两个含有病毒遗传物质。通过在羟基磷灰石上测量DNA重缔合动力学来确定存在的猿猴病毒40基因组当量数。两个流产性转化细胞系每个二倍体细胞含有大约五个病毒基因组当量，而来自第三个流产性转化体的DNA与未感染的BALB/3T3细胞的DNA无法区分。在类似条件下分离的一个标准猿猴病毒40转化体每个细胞含有两个病毒基因组拷贝。流产性转化体似乎也含有完整的病毒基因组，而不是多个部分拷贝。一个每个细胞含有五个拷贝的流产性转化细胞系的亚克隆每个二倍体细胞含有2.7 - 10个病毒遗传物质拷贝。
