title: Herpes simplex type 1-induced Fc receptor binds to the Cgamma2-Cgamma3 interface region of IgG in the area that binds staphylococcal protein A.
abstract: The binding site of immunoglobulin G (IgG) to herpes simplex virus (HSV) type 1-induced Fc receptor was investigated using human IgG Fc intermediate (Fc(i)) fragments, fragment D of staphylococcal protein A (SPA) and chemically modified human IgG. Human IgG Fc(i) fragment composed of one Cgamma2 and two Cgamma3 domains, bound strongly to HSV-1-infected cells. Fragment D, a monovalent subunit of SPA, inhibited the binding of radiolabelled human IgG Fc fragments to the HSV Fc receptor. Reductively methylated human IgG reacted equally well to HSV-infected cells, as did chemically unmodified IgG in contrast to N-acetylimidazole-modified and diethylpyrocarbonate-modifed human IgG, which were unreactive. These results suggest a similar binding site on human IgG for SPA and the HSV-1 Fc receptor with involvement of the amino acid residues Tyr and His but not Lys. The similarities of binding sites on the IgG molecule for the HSV-1 Fc receptor and rheumatoid factors (RF) may be important for understanding the mechanism of RF production in rheumatoid arthritis or other disease states.
authors.affiliation: Department of Virology, Institute of Medical Microbiology, University of Lund, Lund, Sweden.
authors.forename: P J
authors.initials: PJ
authors.lastname: Johansson
authors.forename: F A
authors.initials: FA
authors.lastname: Nardella
authors.forename: J
authors.initials: J
authors.lastname: Sjöquist
authors.forename: A K
authors.initials: AK
authors.lastname: Schröder
authors.forename: P
authors.initials: P
authors.lastname: Christensen
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D000882:Haplorhini; D018259:Herpesvirus 1, Human / Q000276:immunology*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism*; D011485:Protein Binding; D011961:Receptors, Fc / Q000378:metabolism*; D012217:Rheumatoid Factor / Q000378:metabolism; D013205:Staphylococcal Protein A / Q000378:metabolism*
chemical_list: D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D011961:Receptors, Fc; D013205:Staphylococcal Protein A; D012217:Rheumatoid Factor