Identification of B Cell Epitopes of a 30 kDa Babesia equi Merozoite Surface Protein

Abstract

A 30 kDa immunodominant surface antigen (p30) of Babesia equi has been used as a diagnostic antigen. The B cell epitopes on this molecule recognized by horse sera and monoclonal antibody (MAb) against p30, 36/133.97, were determined. A synthetic peptide of p30 with amino acid sequence of ¹²³FYQEVLFKGFEAV ¹³⁵ exhibited strong positive reaction with the infected horse sera. In contrast, MAb 36/133.97 recognized different region of p30, as peptide synthesized with amino acid sequence of ²⁷ASGAVVDFQLESI ³⁹ reacted strongly. In competitive inhibition ELISA, the binding of MAb 36/133.97 to recombinant p30 was inhibited by horse antibodies, although they did not recognize same or an overlapping epitope. The data on B cell epitopes in this study may be important in improving serodiagnostic methods of B. equi infection.