@article{mbs:/content/journal/jgv/10.1099/0022-1317-74-4-745, author = "Olsen, Christopher W. and Corapi, Wayne V. and Jacobson, Richard H. and Simkins, Ronald A. and Saif, Linda J. and Scott, Fred W.", title = "Identification of antigenic sites mediating antibody-dependent enhancement of feline infectious peritonitis virus infectivity", journal= "Journal of General Virology", year = "1993", volume = "74", number = "4", pages = "745-749", doi = "https://doi.org/10.1099/0022-1317-74-4-745", url = "https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-74-4-745", publisher = "Microbiology Society", issn = "1465-2099", type = "Journal Article", 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.", }