Herpes virus production as a marker of repair in ultra-violet irradiated human skin cells of different origin.

Confluent cultures of human skin fibroblasts were irradiated with ultra-violet light 0 to 48 hours before infection with herpes simplex virus type 1 (HSV). The one-cycle viral yield was measured. Different responses were obtained according to the origin of the host cells. (1) Cells from three normal donors showed a dose-dependent recovery of HSV production during the 36--40 hours following U.V. exposure. The recovery was maximal for a dose at which a plateau level of unscheduled DNA synthesis (UDS) was reached (24 Jm-2). (2) In a xeroderma pigmentosum (XP) heterozygote line from a mother of XP children, the level of UDS after irradiation up to 48Jm-2 was normal whereas the extent of recovery of HSV production capacity was lower than that of the normal lines. (3) In strains from two cases of XP children, with a normal UDS (XP variants), the recovery process was slowed down and its extent was lower than in normal or XP heterozygote cells. (4) Excision-deficient XP strains from eight cases of XP children presented either no recovery (two strains having the lowest UDS, less than 2 per cent) or a small recovery, the extent of which was in good agreement with the corresponding level of UDS (between 5 and 30 per cent). Measurement of this recovery seems to be a very sensitive assay for detecting differences in the repair abilities of U.V.-irradiated human skin cells of various origins.