title: The B-oligomer of pertussis toxin deactivates CC chemokine receptor 5 and blocks entry of M-tropic HIV-1 strains.
abstract: Infection of target cells by HIV-1 requires initial binding interactions between the viral envelope glycoprotein gp120, the cell surface protein CD4, and one of the members of the seven-transmembrane G protein-coupled chemokine receptor family. Most primary isolates (R5 strains) use chemokine receptor CCR5, but some primary syncytium-inducing, as well as T cell line-adapted, strains (X4 strains) use the CXCR4 receptor. Signaling from both CCR5 and CXCR4 is mediated by pertussis toxin (PTX)-sensitive G(i) proteins and is not required for HIV-1 entry. Here, we show that the PTX holotoxin as well as its binding subunit, B-oligomer, which lacks G(i)-inhibitory activity, blocked entry of R5 but not X4 strains into primary T lymphocytes. Interestingly, B-oligomer inhibited virus production by peripheral blood mononuclear cell cultures infected with either R5 or X4 strains, indicating that it can affect HIV-1 replication at both entry and post-entry levels. T cells treated with B-oligomer did not initiate signal transduction in response to macrophage inflammatory protein (MIP)-1beta or RANTES (regulated upon activation, normal T cell expressed and secreted); however, cell surface expression of CCR5 and binding of MIP-1beta or HIV-1 to such cells were not impaired. The inhibitory effect of B-oligomer on signaling from CCR5 and on entry of R5 HIV-1 strains was reversed by protein kinase C (PKC) inhibitors, indicating that B-oligomer activity is mediated by signaling events that involve PKC. B-oligomer also blocked cocapping of CCR5 and CD4 induced by R5 HIV-1 in primary T cells, but did not affect cocapping of CXCR4 and CD4 after inoculation of the cultures with X4 HIV-1. These results suggest that the B-oligomer of PTX cross-deactivates CCR5 to impair its function as a coreceptor for HIV-1.
authors.affiliation: Picower Institute for Medical Research, Manhasset, New York 11030, USA.
authors.forename: M
authors.initials: M
authors.lastname: Alfano
authors.forename: H
authors.initials: H
authors.lastname: Schmidtmayerova
authors.forename: C A
authors.initials: CA
authors.lastname: Amella
authors.forename: T
authors.initials: T
authors.lastname: Pushkarsky
authors.forename: M
authors.initials: M
authors.lastname: Bukrinsky
mesh_terms: D065100:CCR5 Receptor Antagonists; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D054407:Chemokine CCL4; D015497:HIV-1 / Q000187:drug effects* / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D008024:Ligands; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology; D008561:Membrane Fusion / Q000187:drug effects / Q000502:physiology; D037342:Pertussis Toxin; D011940:Receptor Aggregation / Q000187:drug effects / Q000502:physiology; D019713:Receptors, CCR5 / Q000187:drug effects / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology / Q000821:virology; D010566:Virulence Factors, Bordetella / Q000737:chemistry / Q000494:pharmacology*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D065100:CCR5 Receptor Antagonists; D054407:Chemokine CCL4; D008024:Ligands; D019402:Macrophage Inflammatory Proteins; D019713:Receptors, CCR5; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D002118:Calcium