Preparation and partial characterization of monoclonal antibodies against the protective protein antigen of Erysipelothrix rhusiopathiae

Thirteen mouse monoclonal antibodies (Mabs) against the protective protein antigen (P64) of Erysipelothrix rhusiopathiae were prepared and partially c haracterized. The titres of the Mabs varied from 200 to 1 638 400 as determ ined by enzyme-linked immunosorbent assay (ELISA). Of the 13 Mabs 10, two a nd one belonged to the IgG(2a), IgG(1) and IgM subclasses, respectively. Al l Mabs reacted strongly with the 64 kDa protein and weakly with the 43 kDa protein upon Western blotting of the alkaline extract (AE) of E. rhusiopath iae. The protective activity (PD50/ml) of die 13 Mabs against E. rhusiopath iae infection in mice varied from <50 to >50 000. These Mabs were classifie d into three groups, highly protective Mabs, moderately protective Mabs and Mabs which did not possess protective activity, based on the protective in dex (ratio of the PD50/ml to the antibody titre). These results suggest tha t the 64 kDa protein is an effective protective antigen, which is easily cl eaved into many small proteins, including the 13 kDa protein, and possesses at least two epitopes related to its protective activity and at least one epitope which is not related tu protection of mice against E. rhusiopathiae infection.