γ-Ray enhanced reactivation of γ-irradiated adenovirus in human cells

An enhanced reactivation of γ-irradiated human adenovirus type 2 (Ad 2) was detected following the infection of normal human fibroblasts which had been pre-irradiated with γ-rays. γ-irradiated or non-irradiated fibroblasts were infected with either non-irradiated or γ-irradiated Ad 2, and at 48 hours after infection cells were examined for the presence of viral structural antigens (Vag) using immunofluorescent staining. Pre-irradiation of the cells with 1 Krad immediately prior to infection resulted in a 5 to 15 fold increase in the survival of this viral function following different γ doses to the virus up to 3 Mrad. For a fixed γ dose of 2 Mrad to the virus this enhancement increased with pre-irradiation dose to the cells up to a maximum factor of 5 to 30 for a dose of 2 Krad. When infection was delayed until 48 hours after irradiation of the cells, this enhancement was reduced to about half the level found for immediate infection.