UV-irradiation of related mouse hybrid cells: similar increase in capacity to replicate intact minute-virus-of-mice but differential enhancement of survival of UV-irradiated virus.

3 hybrid cell lines between mouse fibroblasts (A9) and mouse lymphoma cells (L5178YS) were compared with regard to the ability of UV-pre-irradiated cells to replicate intact (unirradiated) Minute-virus-of-Mice (MVM) and to reactivate UV-irradiated MVM. UV irradiation of cells before virus infection enhanced their ability to plaque intact virus (Enhanced Capacity) to a similar extent in the 3 hybrid cell lines. However, pretreatment of cells with UV radiation enhanced the survival of UV-damaged virus (Enhanced Reactivation) in only 1 of these hybrids. The lack of detectable Enhanced Reactivation in the other hybrids without concomitant change in their Enhanced Capacity, suggests that these processes are at least partly independent. Virus survival in unirradiated cells was similar for all 3 hybrid cell lines, indicating that the absence of detectable Enhanced Reactivation in 2 of the hybrids was not due to the constitutive expression of this process, but might rather result from its loss or extinction. The expression of both Enhanced Capacity and Enhanced Reactivation requires synthesis of protein de novo shortly after cell irradiation.