Conferral of an antiviral state to CD4(+) cells by a zipper motif envelopemutant of the human immunodeficiency virus type 1 transmembrane protein gp41

We showed in a transient coexpression study that a single proline substitut ion for any of the five conserved leucine or isoleucine residues located in the envelope (Env) transmembrane protein gp41 zipper motif of the human im munodeficiency virus type 1 dominantly interferes with wild-type Env-mediat ed viral infectivity. In the present study, we intended to explore the feas ibility of developing a genetic anti-HIV strategy targeting the zipper moti f. Stable HeLa-CD4-LTR-beta-gal clones that harbored silent copies of Tat-r egulated expression cassettes encoding the zipper motif Env mutants were fi rst generated. Expression of any of the five Env mutants in transfectants i nterfered with exogenously expressed homologous HXB2 Env-mediated cytopathi c effects. Mutant transfectants 566, 573, and 580 were further examined. Vi ral transmission mediated by the laboratory-adapted T cell-tropic HXB2, and NL4-3 viruses was greatly reduced in these transfectants compared with tha t observed in the env-defective control Delta KS and wt env transfectants, Moreover, viral replication mediated by the NL4-3 virus and a macrophage-tr opic ADA-GG virus was delayed or reduced in human T cells harboring the mut ant 566 or 580 env construct as opposed to those observed in cells harborin g the control Delta KS or mutant 573 env construct. The wt and mutant Env p roteins formed a hetero-oligomer when they were coexpressed. These results demonstrate that zipper motif Env mutants 566 and 580 confer an anti-HIV st ate to the host CD4(+) cells, which indicates that dominant inhibitory muta nts targeting the gp41 zipper motif might function as genetic anti-HIV agen ts to combat HIV-1 infection.