Identification of excretory-secretory products from larval stages of Ostertagia circumcincta cultured in vitro by SDS-PAGE and immunoblotting

Exsheathing fluid (EF) and excretory-secretory products (ES) of infective third-stage cultured larvae of Ostertagia circumcincta were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Five and seven predominant proteins were found in the EF and ES products, respectively. Immunoblotting by sheep pre-infection serum did not react with any of the EF and ES proteins, but the post-infection serum recognized four proteins of 44.5, 41.5, 38 and 24 kDa of the ES products. None of the EF products was recognized by the post-infection serum. Protectivity of the four proteins remains to be determined.