Characterization of MAbs against FCV VP1 protein. The figure shows results obtained with MAbs representative of each of the five different antibody groups, G1-G5. A Indirect immunofluorescence assays performed using non-infected (−INF) or FCV-infected CRFK cells (+INF). B Plaque-reduction neutralization assay specific for FCV virus, performed as previously described . The FCV virus was preincubated in the absence (-MAb) or presence (+MAb) of MAbs (hybridoma supernatants diluted 1/20).