Host-cell reactivation in mammalian cells

SummaryInvestigations 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.