Cyclic AMP-mediated growth arrest is associated with increased expression of human T cell leukemia virus type I structural and transforming genes.

The effect of increased intracellular cyclic AMP levels on gene expression of the human T cell leukemia virus type I (HTLV-I) provirus was examined. Induction of infected cells to produce elevated levels of cyclic AMP was associated with specific increases in viral surface antigen expression, protein synthesis, p24 release into the supernatant, and RNA levels. The patterns of HTLV-I proviral gene expression observed support results from transfection experiments regarding the function of Tax, Rex, and cyclic AMP in HTLV-I gene regulation. As evidenced by thymidine incorporation, treatment of the infected cells to produce cyclic AMP caused reversible growth arrest. The data indicate that HTLV-I RNA and protein synthesis can proceed at an elevated level in the absence of cell growth. Sustained increases in the intracellular level of cyclic AMP may represent a method for enriching cell cultures in HTLV-I proteins.