CYCLIC AMP-MEDIATED GROWTH ARREST IS ASSOCIATED WITH INCREASED EXPRESSION OF HUMAN T-CELL LEUKEMIA-VIRUS TYPE-I STRUCTURAL AND TRANSFORMINGGENES

The effect of increased intracellular cyclic AMP levels on gene expres sion of the human T cell leukemia virus type I (HTLV-I) provirus was e xamined, Induction of infected cells to produce elevated levels of cyc lic AMP was associated with specific increases in viral surface antige n 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 o f Tax, Rex, and cyclic AMP in HTLV-I gene regulation. As evidenced by thymidine incorporation, treatment of the infected cells to produce cy clic AMP caused reversible growth arrest. The data indicate that HTLV- I RNA and protein synthesis can proceed at an elevated level in the ab sence of cell growth, Sustained increases in the intracellular level o f cyclic AMP may represent a method for enriching cell cultures in HTL V-I proteins.