Characterization of Blastocystis hominis antigens by the enzyme-linked immunosorbent assay (ELISA) and immunoblotting

Abstract

Blastocystis hominis antigens were characterized by ELISA and immunoblotting and compared with those of Giardia lamblia and Entamoeba histolytica to identify species-specific antigens which may be useful for the development of diagnostic assays. SDS-PAGE analysis revealed differences in the polypeptide patterns of the three protozoan antigens. The ELISA performed with homologous and heterologous antigens on mice hyperimmune sera raised against B. hominis was specific as no cross reactions were observed with either G. lamblia or E. histolytica antigens. B. hominis antigens did not cross react with antisera produced against the two heterologous antigens indicating the high specificity of the ELISA. Immunoblotting identified specific antigenic polypeptides for each parasite species and these may be useful for diagnosis. For B. hominis, antigenic polypeptides of molecular weights 66.2 and 57.5 kD were most reactive with homologous mice hyperimmune sera while for G. lamblia, the most reactive polypeptides were of molecular weight cs 74, 66.2 and 50 kD. For E histolytica, polypeptides of molecular weights 66.2 and 57.5 kD were highly reactive. Both the ELISA and immunoblotting can detect specific antibodies and are therefore potentially useful for the diagnosis of B. hominis infection.