STUDY OF ENHANCED REACTIVATION AND INDUCE D MUTAGENESIS OF VACCINIA VIRUS REPAIR-DEFECTIVE CELLS OF HOMOCYSTINURIA

Two lines of fibroblasts isolated from patients with homocystinuria we re characterized by the test of vaccinia virus host-cell reactivation. Xeroderma pigmentosum cells and normal fibroblasts were used as a con trol. Reduced host cell reactivation of the virus and an enhanced leve l of induced virus mutations in comparison with normal cells were reve aled in homocystinuria cells after 4NQO and gamma-ray treatment. Enhan ced reactivation and a corresponding reduced level of gamma-induced mu tagenesis were found in preirradiated normal cells and in the xeroderm a pigmentosum cells. The level of enhanced reactivation of the virus w as virtually the same in preirradiated and nonirradiated homocystinuri a cells, while the level of induced mutagenesis was reduced in both ce lls. This indicates the difference in the capability of the virus syst em for enhanced reactivation to repair potentially lethal and premutat ional DNA damages.