Antigenic profile, isolation and characterization of whole body extract of Paramphistomum gracile

An antigenic component of adult Paramphistomum gracile was characterized by means of indirect enzyme-linked immunosorbent assay (indirect ELISA), sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting using sera from cattle naturally infected with P. gracile, Eurytrema pancreaticum, Fasciola gigantica, Moniezia benedeni, strongylids, Trichuris sp. and Strongyloides sp. The whole body (WB) extracts of P. gracile were fractionated by gel filtration chromatography in a Sephadex G-200 column. It was found that the WB extract fractions, F1-F3 were highly antigenic, F5 was moderately antigenic and F4 was poorly antigenic. For SDS-PAGE and immunoblotting, the antigenic molecules of WB extract and all five fractions were mostly at molecular weights (MW) ranging from 12 to 150 kDa. One antigenic protein of 16 kDa detected in WB extract and F1-F3 was found to give a consistent reaction with sera from infected cattle. The antigenicity of the purified 16 kDa protein was confirmed by immunoblotting and indirect ELISA using a pool of sera and individual serum samples from infected cattle (at 1 : 78 125 dilution) and hyperimmunized rabbit (at 1 : 390 625 dilution). This finding suggests that the 16 kDa protein may be a potential antigen for the immunodiagnosis of cattle paramphistomosis caused by P. gracile.