Host-cell Reactivation in Mammalian Cells

Summary

Investigations are reported regarding the generality of host-cell reactivation (HCR) of U.V.-irradiated virus and factors which influence HCR. No significant differences were found in HCR ability (determined by D₃₇) in 18 different human fibroblast cultures for U.V.-irradiated herpes virus among cells from different organs or from individuals of different sex or age. Two aspects of culture ‘age’ were: (1) the HCR ability of primary cultures increased somewhat with passage number; (2) infection of cultures at increasing times after subculture produced a marked decrease in the level of the second component of the two-component survival curve, as was also found when depleted medium was used. Normal, contact-inhibited mouse cells have a one component survival curve, whereas a transformed culture had an additional, less sensitive component. These combined data indicated that (1) several cell conditions have slight effect on HCR (as measured by D₃₇) and (2) conditions which inhibit cell-growth depress the level of the second component of the survival curve.