Host cell reactivation of Epstein-Barr virus in normal and repair-defective leukocytes.

Epstein-Barr virus (EBV)-induced transformation effi ciencies were quantitated for peripheral blood leukocytes from two patients with xeroderma pigmentosum (XP) and a patient with the related disorder Cockayne's syndrome. By transformed centers or limiting dilution assays, there were no observed differences in transformation efficien cies between XP, Cockayne's syndrome, or normal adult leukocytes. In contrast it was found that when either the leukocytes or the infecting EBV were UV irradiated prior to virus exposure, XP leukocytes showed a greater de crease in ability to undergo in vitro transformation. The doses of the transforming functions of the B95-8 strain of EBV lethal to 37% of the animals were 70, 725, and 750 ergs/sq mm when measured in XP, XP heterozygotic, and normal adult leukocytes, respectively. Transforming ac tivity of UV-irradiated EBV could be partially restored by illuminating infected XP leukocytes with visible light 36 hr after virus exposure. Illumination with visible light had little effect on transformation of neonatal or normal adult leukocytes by UV-irradiated EBV. Colony formation in soft agarose by the resulting lymphoblastoid cell lines estab lished from primary XP or Cockayne's syndrome leuko cytes showed increased sensitivity to UV-irradiation when compared to lymphoblastoid cell lines established from heterozygotic or normal individuals. These results dem onstrate that EBV is similar to other herpesviruses in being subject to host cell reactivation, and the EBV-induced transformation does not require or alter these functions.