ELISA detection of IgG antibody against a recombinant major surface antigen (Nc-p43) fragment of Neospora caninum in bovine sera

Abstract

An ELISA was established to measure bovine IgG directed against the recombinant antigenic determinant of Nc-p43, a major surface antigen of Neospora caninum. In a previous study, two thirds of the C-terminal of the molecule was expressed as a 6 x His tagged protein (Ncp43P) for ELISA using 2/3 of the N-terminal of SAG1 from Toxoplasma gondii as a control (TgSAG1A). Among 852 cattle sera collected from stock farms scattered nation-wide, 103 sera (12.1%) were found to react with Ncp43P positively, but no positive reaction was observed with TgSAG1A. This study shows that Ncp43P could be available as an efficient antigen for the diagnosis of neosporosis in cattle. Furthermore, it together with TgSAG1A, could be useful for the differential diagnosis of N. caninum and T. gondii infections in other mammals.

Fig. 1

Cloning of genes from the C-terminal 2/3 fragment of Nc-p43 from Neospora caninum (Ncp43C) and from the N-terminal 2/3 fragment of SAG1 from Toxoplasma gondii (TgSAG1N) in pQE30 vector.

Fig. 2

SDS-PAGE of M15 strain transformed with Ncp43C (Ncp43P) and TgSAG1N (TgSAG1A) plasmids, which were expressed by IPTG induction (i). Ni-NTA column purified antigens were represented by 26 kDa and 19 kDa bands. Numerals on the left indicated molecular mass as kDa.