MHV S peplomer protein expressed by a recombinant vaccinia virus vector exhibits IgG Fc-receptor activity.
We have previously shown that cells infected with mouse hepatitis virus (MHV) bind rabbit, mouse, and rat IgG by the Fc portion of the IgG molecule. This Fc-binding activity appeared to be mediated by the MHV S protein. S protein could also be precipitated from MHV-infected cells by a monoclonal antibody directed against the murine Fc gamma receptor (Fc gamma R). To prove definitively that the S protein mediates Fc-binding activity, we have expressed the MHV S protein utilizing recombinant vaccinia viruses. The anti-Fc gamma R monoclonal antibody, 2.4G2, precipitated recombinant S protein in cells of murine, human, and rabbit origin. Since the anti-Fc receptor monoclonal antibody does not react with human and rabbit Fc receptors these results demonstrate that the epitope recognized by this antibody is carried on the MHV S protein and is not murine in origin. Examination of various MHV isolates and escape mutants failed to identify the precise sequences in S responsible for the molecular mimicry of the murine Fc gamma R. These data are consistent with the hypothesis that a previously identified region of similarity between the S protein and the Fc gamma R mediates this activity. The Fc binding activity of S was expressed on the cell surface, since MHV-JHM-infected cells, but not uninfected cells, formed rosettes with anti-sheep red blood cell (SRBC) antibody-coated SRBC. The anti-Fc gamma R monoclonal antibody neutralized MHV-JHM and inhibited syncytium formation induced by the MHV S protein.
Oleszak
E L
EL
Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, Houston 77030.
Perlman
S
S
Leibowitz
J L
JL
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000943:Antigens, Differentiation / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D003429:Cross Reactions; D004252:DNA Mutational Analysis; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism*; D008562:Membrane Glycoproteins; D006517:Murine hepatitis virus / Q000276:immunology / Q000378:metabolism*; D009500:Neutralization Tests; D011961:Receptors, Fc / Q000276:immunology / Q000378:metabolism*; D017452:Receptors, IgG; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D064370:Spike Glycoprotein, Coronavirus; D013329:Structure-Activity Relationship; D014759:Viral Envelope Proteins / Q000276:immunology / Q000378:metabolism*; D014760:Viral Fusion Proteins / Q000276:immunology / Q000378:metabolism*; D014763:Viral Matrix Proteins
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D007141:Immunoglobulin Fc Fragments; D008562:Membrane Glycoproteins; D011961:Receptors, Fc; D017452:Receptors, IgG; D011994:Recombinant Proteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D014763:Viral Matrix Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus