ANALYSIS OF 3' TERMINALS OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 TRANSCRIPTS IN PERSISTENTLY INFECTED-CELLS

To examine the 3' terminal processing of human immunodeficiency virus type 1 (HIV-1) transcripts and the effects of phorbol ester (TPA) on t his processing, cellular RNAs from persistently infected T cells (MOLT -4) or promonocytes (U937), with or without TPA treatment, were analyz ed. To map the 3' terminals of viral transcripts, the RNA samples were examined by RNase-protection assay with an HIV-1 long terminal repeat (LTR) antisense riboprobe. Without TPA treatment, the viral transcrip ts initiated at the cap site in 5' LTR and polyadenylated at poly(A) s ite in 3' LTR were dominantly detected in both types of cells. This an alysis demonstrated that some occlusion mechanism inactivating the pol y(A) site in 5' LTR might exist in these infected cells. After TPA tre atment, we found a dramatic shift in the protected patterns of viral t ranscripts in MOLT-4 cells, while the shift in U937 cells was less dra matic. These results suggested that the primary factor(s) involved in the observed effect of TPA might be cellular. We also demonstrated tha t the shift in the protected patterns of viral transcripts was associa ted with increased steady-state levels of viral transcripts. These res ults indicated that the factors involved in the TPA-induced shift migh t have some relation to the trans-activation of HIV-1 by similar subst ances.