title: Ebola virus secretory glycoprotein (sGP) diminishes Fc gamma RIIIB-to-CR3 proximity on neutrophils.
abstract: Previous studies have shown that Ebola virus' secretory glycoprotein (sGP) binds to Fc gamma RIIIB (CD16b) and inhibits L-selectin shedding. In this study, we test the hypothesis that sGP interferes with the physical linkage between CR3 and Fc gamma RIIIB. Neutrophils were stained with rhodamine-conjugated anti-CD16b mAb (which does not inhibit sGP binding) and fluorescein-conjugated anti-CR3 mAb reagents and then incubated in media with or without sGP. Physical proximity between fluorochrome-labeled CR3 and Fc gamma RIIIB on individual cells was measured by resonance energy transfer (RET) imaging, quantitative RET microfluorometry, and single-cell imaging spectrophotometry. Cells incubated with control supernatants displayed a significant RET signal, indicative of physical proximity (<7 nm) between CR3 and Fc gamma RIIIB. In contrast, cells exposed to sGP showed a significant reduction in the CR3-Fc gamma RIIIB RET signal using these methods. Interestingly, colocalization and cocapping of CR3 and Fc gamma RIIIB were not affected, suggesting that the proximity of these two receptors is reduced without triggering dissociation. Thus, sGP alters the physical linkage between Fc gamma RIIIB and CR3.
authors.affiliation: Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Kindzelskii
authors.forename: Z
authors.initials: Z
authors.lastname: Yang
authors.forename: G J
authors.initials: GJ
authors.lastname: Nabel
authors.forename: R F
authors.initials: RF
authors.lastname: Todd
authors.forename: H R
authors.initials: HR
authors.lastname: Petty
mesh_terms: D000328:Adult; D003592:Cytophotometry; D029043:Ebolavirus / Q000276:immunology*; D004735:Energy Transfer / Q000276:immunology; D006023:Glycoproteins / Q000502:physiology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D016177:Macrophage-1 Antigen / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D011940:Receptor Aggregation / Q000276:immunology; D017452:Receptors, IgG / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D014764:Viral Proteins
chemical_list: D006023:Glycoproteins; D007166:Immunosuppressive Agents; D016177:Macrophage-1 Antigen; D017452:Receptors, IgG; D014764:Viral Proteins; C110613:secreted glycoprotein, Ebola virus