Mes A M, Hassell J A
J Virol. 1982 May;42(2):621-9. doi: 10.1128/JVI.42.2.621-629.1982.
To determine whether small or middle T-antigen (or both) of polyoma virus is required for transformation, we constructed mutants of recombinant plasmids which bear the viral oncogene and measured the capacity of these mutants to transform rat cells in culture. Insertion and deletion mutations in sequences encoding small and middle T-antigens (79.7, 81.3, and 82.9 map units) rendered the DNA incapable of causing transformation by the focus assay. Similar mutations in sequences that encoded middle but not small T-antigen (89.7, 92.1, and 96.5 map units) generally abolished the transforming activity of the DNA. However, two mutants (pPdl1-4 and PPd12-7) that carried deletions at 92.1 map units retained the capacity to transform cells; pPdl1-4 did so at frequencies equal to those of the parental plasmid, whereas pPdl2-7 transformed at 10% the frequency of its antecedent. From these studies we conclude that small T-antigen alone is insufficient to cause transformation and that middle T-antigen is required for transformation, either in combination with small T-antigen or by itself.
为了确定多瘤病毒的小T抗原或中T抗原（或两者）是否是转化所必需的，我们构建了携带病毒癌基因的重组质粒突变体，并检测了这些突变体在培养物中转化大鼠细胞的能力。编码小T抗原和中T抗原（79.7、81.3和82.9图谱单位）的序列中的插入和缺失突变使DNA无法通过焦点试验导致转化。编码中T抗原但不编码小T抗原（89.7、92.1和96.5图谱单位）的序列中的类似突变通常会消除DNA的转化活性。然而，两个在92.1图谱单位处携带缺失的突变体（pPdl1-4和PPd12-7）保留了转化细胞的能力；pPdl1-4的转化频率与亲本质粒相同，而pPdl2-7的转化频率是其前身的10%。从这些研究中我们得出结论，单独的小T抗原不足以导致转化，中T抗原对于转化是必需的，要么与小T抗原联合，要么单独起作用。
