U.V. Enhanced Reactivation of U.V.- and γ-irradiated Adenovirus in Cockayne Syndrome and Xeroderma Pigmentosum Fibroblasts

Summary

U.V.-enhanced reactivation (UVER) of both U.V.-irradiated and γ-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 Ad 2, 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 γ-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 J m⁻² for XP 25RO, 0·14 J m⁻² for XP 12BE, 0·8 J m⁻² for XP 5BE and XP 6BE, and 1·6–5·0 J m⁻² for CS 1BE and CS 3BE) were considerably lower than those yielding peak UVER in normal strains (10–15 J m⁻²). XP variant strains (XP 4BE and XP 115LO), however, showed substantially lower levels of UVER than normal strains.