title: Replication of different clones of human immunodeficiency virus type 1 in primary fetal human astrocytes: enhancement of viral gene expression by Nef.
abstract: Dementia is a common complication of AIDS which is associated with human immunodeficiency virus type 1 (HIV-1) infection of brain macrophages and microglia. Recent studies have shown that astrocytes are also infected in the brain but HIV-1 replication in these cells is restricted. To determine virus specificity of this restriction we tested the expression of 15 HIV-1 molecular clones in primary human fetal astrocytes by infection and DNA transfection. Infection with cell-free viruses was poorly productive and revealed no clone-specific differences. In contrast, transfected cells produced transiently high levels of HIV-1 p24 core antigen, up to 50 nanograms per ml culture supernatant, and nanogram levels of p24 were detected 3-4 weeks after transfection of some viral clones. The average peak expression of HIV-1 in astrocytes varied as a function of viral clone used by a factor of 15 but the differences and the subsequent virus spread did not correlate with the tropism of the viral clones to T cells or macrophages. Functional vif, vpu, and vpr genes were dispensable for virus replication from transfected DNA, but intact nef provided a detectable enhancement of early viral gene expression and promoted maintenance of HIV-1 infection. We conclude that primary astrocytes present no fundamental barriers to moderate expression of different strains of HIV-1 and that the presence of functional Nef is advantageous to virus infection in these cells.
mesh_terms: D001253:Astrocytes / Q000821:virology*; D018929:Cell Culture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D015754:Genes, nef / Q000502:physiology*; D016655:HIV Core Protein p24 / Q000032:analysis; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D012680:Sensitivity and Specificity; D013997:Time Factors; D014162:Transfection; D014779:Virus Replication / Q000502:physiology