X irradiation-induced transcription from the HIV type 1 long terminal repeat.

It has been previously shown in vitro and in vivo that the human immunodeficiency virus type 1 can be dramatically enhanced by certain heterologous viral, chemical, and physical (ultraviolet irradiation) agents. A common denominator shared by these agents is their ability to cause stress responses in cells. To analyze if a similar effect could occur by X irradiations, we tested the in vitro effect of X rays on HIV LTR-directed gene expression. The results demonstrate that the HIV-1 LTR is activated by X irradiation in a dose- and time-dependent manner, in all cell types tested, including epitheloid, fibroblast, and lymphoid cell lines. This study raises the possibility that exposure of AIDS patients to ionizing radiation (e.g., during treatment of epidemic Kaposi's sarcoma) could play a role in the activation of HIV-1 in vivo.