4th International AIDS Conference Stockholm, Sweden. — June 12-16, 1988

Int Conf AIDS. 1988 Jun 12-16;4:1.117 (abstract no. 1019)

N. Ahmad, R. J. Mervis, E. P. Lillehoj and S. Venkatesan
Lab. Mol. Microbiol., National Institute Allergy & Infectious. Diseases, Bethesda, Md., 20892, USA.

OBJECTIVE: To investigate the mechanism of HIV art/trs induced trans-activation.

METHODS: A replication defective HIV proviral DNA with a single nonsense codon in the art/trs ORF was complemented with expressible cDNA encoding art protein in DNA transfections using SW480 cells. art/trs effect on the transient expression of HIV env and gag ORFs fused to HIV LTR or an heterologous promoter was also analyzed. The complexity of the virus specific transcripts from proviral or subgenomic plasmid transfectants were examined by RNA filter blotting and nuclease S1 analysis of potential splice junctions.

RESULTS: art mediated activation of the art mutant provirus was accompanied by 1) vigorous expression of env gp160 and gag proteins, 2) increased levels of all species of viral RNAs, 3) marked increase in the relative levels of spliced 4.3 kb env mRNA, 4) complete shutdown of the HIV B ORF expression, and 5) altered splicing of the 1.8/2.0 kb RNA species leading to relative enrichment of tat and art transcripts. Using subgenomic plasmids containing HIV env ORF (in spliced or prespliced configuration) fused to either HIV LTR or an heterologous promoter, art/trs protein was shown to be absolutely required for the expression of env gp160, although env mRNA was transcribed efficiently in these systems in the absence of art/trs. However, art/trs was not essential for HIV gag expression from DNAs containing only the gag or gag and poi ORFs.

CONCLUSION: The above results support the notion that art/trs overcomes the effects of a cis regulatory element inherent in the HIV env sequences that prevents the efficient splicing and/or transport from the nucleus of the transcripts containing these sequences.

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