Prasad I, Zouzias D, Basilico C
J Virol. 1976 May;18(2):436-44. doi: 10.1128/JVI.18.2.436-444.1976.
The interaction of polyoma virus with a continuous line of rat cells was studied. Infection of these cells with polyoma did not cause virus multiplication but induced transformation. Transformed cells did not produce infectious virus, but in all clones tested virus was rescuable upon fusion with permissive mouse cells. Transformed rat cells contained, in addition to integrated viral genomes, 20 to 50 copies of nonintegrated viral DNA equivalents per cell (average). "Free" viral DNA molecules were also found in cells transformed by the ts-a and ts-8 polyoma mutants and kept at 33 C. This was not due to a virus carrier state, since the number of nonintegrated viral DNA molecules was found to be unchanged when cells were grown in the presence of antipolyoma serum. Recloning of the transformed cell lines produced subclones, which also contained free viral DNA. Most of these molecules were supercoiled and were found in the muclei of the transformed cells. The nonintegrated viral DNA is infectious. Its specifici infectivity is, however, about 100-fold lower than that of polyoma DNA extracted from productively infected cells, suggesting that these molecules contain a large proportion of defectives.
研究了多瘤病毒与大鼠细胞连续系的相互作用。用多瘤病毒感染这些细胞不会导致病毒增殖，但会诱导细胞转化。转化后的细胞不产生感染性病毒，但在所有测试的克隆中，与允许性小鼠细胞融合后病毒均可被拯救。除整合的病毒基因组外，转化后的大鼠细胞每个细胞平均还含有20至50个非整合病毒DNA等效拷贝。在由ts-a和ts-8多瘤病毒突变体转化并保持在33℃的细胞中也发现了“游离”病毒DNA分子。这并非由于病毒携带状态，因为当细胞在抗多瘤病毒血清存在下生长时，发现非整合病毒DNA分子的数量没有变化。对转化细胞系进行再克隆产生了亚克隆，这些亚克隆也含有游离病毒DNA。这些分子大多是超螺旋的，存在于转化细胞的细胞核中。非整合病毒DNA具有感染性。然而，其比感染性比从生产性感染细胞中提取的多瘤病毒DNA低约100倍，这表明这些分子包含很大比例的缺陷型。
