Das K S, Christensen J R, Balduzzi P C
Virology. 1986 Oct 30;154(2):415-9. doi: 10.1016/0042-6822(86)90469-1.
A cloned version of avian sarcoma virus UR2, plasmid pKD6, which includes the full, nonpermuted proviral sequence between two LTR regions, has been prepared. The plasmid is biologically active in transfection experiments, even when intact. Two transformation-defective mutants with nonoverlapping deletions within the transforming gene ros were constructed from pKD6. These mutants recombine to produce transforming virus when mixed DNA from both is used to transfect chick embryo fibroblasts along with helper virus DNA. However, recombination was not readily detected when cells were coinfected with fluids harvested from cultures separately transfected with DNA from each mutant. This, and marker rescue experiments with a temperature-sensitive mutant of UR2 defective in transformation but able to replicate, suggest that deletion mutants of UR2 do not propagate efficiently.
已经制备了禽肉瘤病毒UR2的克隆版本——质粒pKD6，它包含两个长末端重复序列（LTR）区域之间完整的、未重排的前病毒序列。该质粒在转染实验中具有生物学活性，即使是完整的时候。从pKD6构建了两个在转化基因ros内具有非重叠缺失的转化缺陷型突变体。当来自这两个突变体的混合DNA与辅助病毒DNA一起用于转染鸡胚成纤维细胞时，这些突变体重组产生转化病毒。然而，当用分别转染了每个突变体DNA的培养物收获的液体共同感染细胞时，重组并不容易检测到。这一点，以及用UR2的一个在转化方面有缺陷但能够复制的温度敏感型突变体进行的标记拯救实验，表明UR2的缺失突变体不能有效地增殖。
