HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 LONG TERMINAL REPEAT QUASI-SPECIES DIFFER IN BASAL TRANSCRIPTION AND NUCLEAR FACTOR RECRUITMENT IN HUMAN GLIAL-CELLS AND LYMPHOCYTES

The generation of genomic diversity during the course of infection has the potential to affect all aspects of HIV-1 replication, including e xpression of the proviral genome. To gain a better understanding of th e impact of long terminal repeat (LTR) sequence diversity on LTR-direc ted gene expression in cells of the central nervous system (CNS) and i mmune system, we amplified and cloned LTRs from proviral DNA in HIV-1- infected peripheral blood. Sequence analysis of nineteen LTRs cloned f rom 2 adult and 3 pediatric patients revealed an average of 33 nucleot ide changes (with respect to the sequence of the LAI LTR) within the 4 55-bp U3 region, Transient expression analyses in cells of neuroglial and lymphocytic origin demonstrated that some of these LTRs had activi ties which varied significantly from the LAI LTR in U-373 MG cells (an astrocytoma cell line) as well as in Jurkat cells (a CD4-positive lym phocyte cell line). While LTRs which demonstrated the highest activiti es in U-373 MG cells also yielded high activities in Jurkat cells, the LTRs were generally more active in Jurkat cells when compared to the LAI LTR, Differences in LTR sequence also resulted in differences in t ranscription factor recruitment to cis-acting sites within the U3 regi on of the LTR, as demonstrated by electrophoretic mobility shift assay s. In particular, naturally occurring sequence variation impacted tran scription factor binding to an activating transcription factor/cAMP re sponse element binding (ATF/CREB) binding site (located between the LE F-1 and distal NF-kappa B transcription factor binding sites) that we identified in previous studies of the HIV-1 LTR. These findings sugges t that LTR sequence changes can significantly affect basal LTR functio n and transcription factor recruitment, which may, in turn, alter the course of viral replication in cells of CNS and immune system origin.