title: Identification of antigenic sites mediating antibody-dependent enhancement of feline infectious peritonitis virus infectivity.
abstract: We have previously demonstrated antibody-dependent enhancement of feline infectious peritonitis virus (FIPV) infection of macrophages using both virus-specific antisera and monoclonal antibodies (MAbs) to the spike (S) protein of FIPV. To increase our understanding of this phenomenon, six representative MAbs from a previously documented group of 12 enhancing MAbs were used to identify epitopes that mediate antibody-dependent enhancement of FIPV infectivity. Analysis of the results of kinetics-based competitive ELISA (K-cELISA) among these six enhancing MAbs grouped the epitopes into two clusters. Because transmissible gastroenteritis virus (TGEV) and FIPV are so closely related antigenically, we also conducted K-cELISA experiments between the FIPV MAbs and TGEV S protein-specific MAbs for which the epitopes had previously been mapped to specific sites on the TGEV S protein. Results of these assays indicated that the two FIPV epitope clusters are homologues of the previously defined TGEV S protein sites A and E/F. In addition, two TGEV S protein-specific MAbs also induced antibody-dependent enhancement of FIPV infection of macrophages. This functional cross-reactivity provides further support for the close antigenic relationship between FIPV and TGEV. Our results provide a preliminary localization of several enhancing epitopes within the amino acid sequence of the FIPV S protein.
authors.affiliation: Department of Microbiology, Immunology, and Parasitology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853.
authors.forename: C W
authors.initials: CW
authors.lastname: Olsen
authors.forename: W V
authors.initials: WV
authors.lastname: Corapi
authors.forename: R H
authors.initials: RH
authors.lastname: Jacobson
authors.forename: R A
authors.initials: RA
authors.lastname: Simkins
authors.forename: L J
authors.initials: LJ
authors.lastname: Saif
authors.forename: F W
authors.initials: FW
authors.lastname: Scott
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology*; D000936:Antigen-Antibody Complex / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology*; D002415:Cats; D016765:Coronavirus, Feline / Q000276:immunology / Q000472:pathogenicity*; D000939:Epitopes; D066298:In Vitro Techniques; D008264:Macrophages / Q000276:immunology / Q000382:microbiology*; D005760:Transmissible gastroenteritis virus / Q000276:immunology; D014764:Viral Proteins / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface; D000956:Antigens, Viral; D000939:Epitopes; D014764:Viral Proteins; C064484:spike protein S, Transmissible gastroenteritis virus