DNA Damage and Biological Function of Human Adenovirus after U.V.-irradiation

Human adenovirus type 2 was irradiated with U.V.-light, and the radiosensitivity of several viral functions was determined and correlated with the damage in the viral DNA. The D37 for plaque formation and clone inhibition was found to be 2·1 × 103 erg/mm3 and 6·4 × 103 erg/mm2, respectively. Thymine dimers, cross-links and single-strand breaks were detected in the viral DNA. The fraction of thymine present as dimer was 1·9 × 10−6/erg/mm2, and the number of U.V. induced single-strand breaks was 21/erg/mm2/1012 daltons. An average of 30 dimers and one single-strand break were induced per lethal hit as measured by plaque formation. The addition of caffeine to the plaquing medium was found to reduce the survival of U.V.-irradiated virus, suggesting the possibility of a host-mediated repair mechanism.