title: T-tropic human immunodeficiency virus (HIV) type 1 Nef protein enters human monocyte-macrophages and induces resistance to HIV replication: a possible mechanism of HIV T-tropic emergence in AIDS.
abstract: Increasing interest has been devoted to the role that monocyte-macrophages play in the pathogenesis of AIDS. The hypothesis of an involvement in AIDS pathogenesis of human/simian immunodeficiency virus (HIV/SIV) Nef also is currently under evaluation by many investigators. The original basis of this hypothesis came from evidence that monkeys infected with a nef-deleted SIV strain failed to develop simian AIDS. Here, we show that treatment of human monocyte-derived macrophages (MDM) with recombinant HIV-1 Nef protein (rNef) induces a strong inhibition of the replication of either macrophage (M-) or dual-tropic HIV-1 strains. Through cytofluorimetric analyses, we detected internalization of FITC-conjugated rNef in MDM as early as 6 h after treatment. Confocal microscope observations demonstrated that the intracellular distribution of internalized rNef was identical to that of endogenously produced Nef. Down-regulation of the CD4 HIV receptor detected upon rNef treatment of MDM suggested that the rNef-induced HIV inhibition occurred at the virus entry step. This deduction was strengthened by the observation that CD4-independent infection was totally insensitive to rNef treatment. The specificity of all observed effects was demonstrated by immunodepletion of rNef. Finally, we showed that the resistance to HIV replication induced by rNef treatment in MDM favours the spread of T-tropic over M-tropic HIV strains in doubly infected CD4(+) lymphocyte-MDM co-cultures. We propose that extracellular Nef contributes to AIDS pathogenesis by inducing resistance to M-tropic HIV replication in MDM, thereby facilitating the switching from M- to T-tropic HIV prevalence that correlates frequently with AIDS progression.
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Alessandrini
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Anna Claudia
authors.initials: AC
authors.lastname: Santarcangelo
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Olivetta
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Ferrantelli
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: d'Aloja
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Katherina
authors.initials: K
authors.lastname: Pugliese
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Elvira
authors.initials: E
authors.lastname: Pelosi
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Cristiana
authors.initials: C
authors.lastname: Chelucci
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Mattia
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Peschle
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Verani
authors.affiliation: Laboratory of Virology1, Laboratory of Haematology-Oncology2 and Laboratory of Clinical Biochemistry3, Istituto Superiore di Sanità, Viale Regina Elena 299, 0061 Roma, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Federico
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000821:virology*; D002478:Cells, Cultured; D054407:Chemokine CCL4; D018920:Coculture Techniques; D018450:Disease Progression; D015536:Down-Regulation / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects; D005434:Flow Cytometry; D015693:Gene Products, nef / Q000378:metabolism* / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism / Q000821:virology*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism / Q000821:virology*; D015728:Receptors, HIV / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D015704:CD4 Antigens; D054407:Chemokine CCL4; D015693:Gene Products, nef; D019402:Macrophage Inflammatory Proteins; D015728:Receptors, HIV; D054311:nef Gene Products, Human Immunodeficiency Virus