U.V. enhanced reactivation of U.V.-and gamma-irradiated adenovirus in Cockayne syndrome and Xeroderma pigmentosum fibroblasts.

U.V.-enhanced reactivation (UVER) of both U.V.-irradiated and gamma-irradiated human adenovirus type 2 (Ad 2) was examined following the infection of a variety of Cockayne Syndrome (CS) and Xeroderma pigmentosum (XP) fibroblast strains which had been pre-irradiated with U.V. light. U.V.-irradiated or non-irradiated fibroblasts were infected with either non-irradiated or irradiated Ad2, and at 48 hours after infection cells were examined for the presence of viral structural antigens (Vag) using immunofluorescent staining. Normal levels of UVER (i.e. 2-4 fold) of U.V.- and of gamma-irradiated Ad 2 were detected in 2 CS strains (CS IBE and CS 3BE), 2 XP complementation group A strains (XP 12BE and XP 25RO), and 2 XP complementation group D strains (XP 5BE and XP 6BE), although the U.V. doses to these mutant cells which resulted in peak UVER values (0 . 2 Jm-2 for XP 25RO, 0 . 14 Jm-2 for XP 12BE, 0 . 8 Jm-2 for XP 5BE and XP 6BE, and 1 . 6-5 . 0 Jm-2 for CS 1BE and CS 3BE) were considerably lower than those yielding peak UVER in normal strains (10-15 Jm-2). XP variant strains (XP 4BE and XP 115LO), however, showed substantially lower levels of UVER than normal strains.