VIF-NEGATIVE HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 PERSISTENTLY REPLICATES IN PRIMARY MACROPHAGES, PRODUCING ATTENUATED PROGENY VIRUS

The vif gene of human immunodeficiency virus type 1 (HIV-1) is require d for efficient infection of primary T lymphocytes. In this study, we investigated in detail the role of vif in productive infection of prim ary monocyte-derived macrophages (MDM). Viruses carrying missense or d eletion mutations in vif were constructed on the background of the mon ocytotropic recombinant NLHXADA-GP. Using MDM from multiple donors, we found that vif mutants produced in complementing or partially complem enting cell lines were approximately 10% as infectious as wild-type vi rus when assayed for incomplete, complete, and circularized viral DNA molecules by quantitative PCR amplification or for viral core antigen p24 production by enzyme-linked immunosorbent assay. We then determine d the structure and infectivity of vif mutant HIV-1 by using MDM exclu sively both for virus production and as targets for infection. Biosynt hetic labeling and immunoprecipitation analysis of sucrose cushion-pur ified vif-negative HIV-1 made in MDM revealed that the virus had reduc ed p24 content compared with wild-type HIV-1. Cell-free MDM-derived vi f mutant HIV-1 was infectious in macrophages as determined by the synt hesis and maintenance of full-length viral DNA and by the production o f particle-associated viral RNA, but its infectivity was approximately 2,500-fold lower than that of wild-type virus whose titer was determi ned in parallel by measurement of the viral DNA burden. MDM infected w ith MDM-derived vif-negative HIV-1 were able to transmit the virus to uninfected MDM by cocultivation, confirming the infectiousness of this virus. We conclude that mutations in vif significantly reduce but do not eliminate the capacity of HIV-1 to replicate and produce infectiou s progeny virus in primary human macrophages.