INTEGRATION IS REQUIRED FOR PRODUCTIVE INFECTION OF MONOCYTE-DERIVED MACROPHAGES BY HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Certain human immunodeficiency virus type 1 (HIV-1) isolates are able to productively infect nondividing cells of the monocyte/macrophage lineage. We have used a molecular genetic approach to construct two different HIV-1 integrase mutants that were studied in the contest of an infectious, macrophage-tropic HIV-1 molecular clone. One mutant, HIV-1(Delta D(35)E), containing a 37-residue deletion within the central, catalytic domain of integrase, was noninfectious in both peripheral blood mononuclear cells and monocyte-derived macrophages. The HIV-1(Delta D(35)E), mutant, however, exhibited defects in the assembly and/or release of progeny virions in transient transfection assays, as well as defects in entry and/or viral DNA synthesis during the early stages of monocyte-derived macrophage infection. The second mutant, HIV-1(D116N/8), containing a single Asp-to-Asn substitution at the invariant Asp-116 residue of integrase, was also noninfectious in both peripheral blood mononuclear cells and monocyte-derived macrophages but, in contrast to HIV-1(Delta D(35)E), was indistinguishable from wild-type virus in reverse transcriptase production. PCR analysis indicated that HIV-1(D116N/8) entered monocyte-derived macrophages efficiently and reverse transcribed its RNA but was unable to complete its replication cycle because of a presumed block to integration, These data are consistent with the hypothesis that integration is an obligate step in productive HIV-1 infection of activated peripheral blood mononuclear cells and primary human macrophage cultures.