trans-dominant interference with human immunodeficiency virus type 1 replication and transmission in CD4(+) cells by an envelope double mutant

We previously reported that a human immunodeficiency virus type 1 (HIV-1) e nvelope (Env) mutant with the whole cytoplasmic domain deleted, denoted mut ant TC, is able to dominantly interfere with wild-type (wt) virus infectivi ty, In the present study, the feasibility of developing a dominant negative mutant-based genetic anti-HIV strategy targeting the gp41 cytoplasmic doma in was investigated. Mutants TC and 427,TC, a TC derivative. with a Trp-to- Ser substitution introduced into residue 427 in the CD l-binding site, and a series of mutants with deletions in the cytoplasmic domain, effectively t rans-dominantly interfered with wt Env-mediated viral infectivity, as demon strated by an env trans-complementation assay. The syncytium formation-defe ctive 427,TC double mutant not only inhibited heterologous LAV and ELI Env- mediated viral infectivity but also interfered with syncytium formation and infectivity mediated by the Env proteins of the two primary isolates 92BR and 92US, Stable HIeLa-CD4-LTR-beta-gal clones that harbored Tat-controlled expression cassettes encoding the control Delta KS, which had a deletion i n the env gene, wt, or mutant env gene were generated. Viral transmission m ediated by laboratory-adapted T-cell-tropic HXB2 and NL4-3 viruses was grea tly reduced in the TC and 427,TC transfectants compared to that observed in the control Delta KS and wt transfectants. Viral replication caused by HXB 2 and NL4-3 viruses and by macrophage-tropic ConB and ADA-GG viruses was de layed or reduced in human CD4(+) T cells transfected with the 427;TC env co nstruct compared to that observed in cells transfected with the control Del ta KS or TC env construct. The lack of significant interference by TC mutan t was due neither to the lack of TC env gene integration into host DNA nor to the lack of TC Env expression upon Tat induction. These results indicate that this 427,TC Env double mutant has a role in the development of trans- dominant mutant-based genetic anti-HIV strategies.