Trial of Antisense RNA Inhibition of HIV Replication and Gene Expression

We examined the feasibility of antisense RNA inhibition of human immunodeficiency virus (HIV) replication. In the first experiment, we established CD4⁺ T-cell lines constitutively expressing various antisense HIV sequences using the retrovirus-mediated gene transfer technique. These cell lines were tested for their ability to withstand HIV de novo infection. In this challenge assay, however, we could not detect any significant difference in the survival rate between these genetically engineered cell lines and control T cells. In the second approach, the effects of antisense sequences on Tat expression were studied by monitoring the activities of reporter enzymes. A functional Tat expression vector and the antisense sequence expression vector were co-introduced into HeLa cells stably transfected with either the HIV-long terminal repeat (LTR) directed chloramphenicol acetyltransferase (CAT) or luciferase. Although the concentration of the antisense RNA was at least 10-fold higher than that of the sense Tat mRNA in cells, these antisense sequences could not inhibit transactivation of HIV-LTR. Regulation of HIV gene expression has proven to be very complicated and Tat transactivation of the HIV-LTR is extraordinarily strong. Consequently, it may be difficult to block HIV replication by the antisense strategy.