Antisense RNA sequences targeting the 5 ' leader packaging signal region of human immunodeficiency virus type-1 inhibits viral replication at post-transcriptional stages of the life cycle

Antisense RNA has proven a potent inhibitor of gene expression and has the potential to inhibit retroviral replication at a number of stages in the vi rus life cycle by targeting both viral and cellular RNA sequences. Antisens e RNA complementary to three target regions in the 5' leader/LTR of human i mmunodeficiency virus type-1 (HIV-1), the TAR region, the primer binding si te and the splice donor (SD)-packaging signal (psi) region were stably expr essed from the CMV IE promoter in Jurkat cells, and expression confirmed by RT-PCR. When challenged with HIV-II cell lines expressing antisense RNA ta rgeting the SD/psi region showed significant inhibition of replication (at up to 10(6) TCID 50/ml). These sequences were also expressed in lymphocytes after transduction using recombinant retroviruses and one sequence complem entary to the SD/psi region inhibited replication of HIV-1. A co-transfecti on assay using COS-1 cells was also developed both to confirm the antiviral potential of these sequences, and to determine the predominant site of act ion of these molecules. Antisense RNAs targeting the psi region and one seq uence complementary to the TAR region inhibited expression of viral protein ; furthermore, analyses of relative levels of cellular and virion RNA from these assays suggest each of these antisense molecules exerts its effect at an early stage in the transcription-translation pathway, while the longer of the sequences also inhibited packaging of virion RNA. These results sugg est that the packaging signal (psi) of HIV-1 represents an attractive targe t for antisense RNA-based gene therapy, although the main mode of action of such molecules may well be through antisense effects at an earlier stage o f replication than packaging.