Significance of a common 65 kDa antigen in the experimental fasciolosis and toxoplasmosis.

In the current study, cross-reaction between two important zoonotic parasites; extracellular helminthes Fasciola gigantica and intracellular protozoa Toxoplasma gondii was proved by enzyme linked immunosorbent assay. Five antigens were used to identify and compare the cross-binding activities in the prepared antisera. Two F. gigantica antigens; adult flukes (FgA) and eggs (FgEA) were used to detect IgG in T. gondii naturally infected human sera (TgIHS) and experimentally infected sera of sheep (TgISS), mice (TgIMS) and rats (TgIRS). Three types of T. gondii antigens; RH (TgRHA), local sheep isolate (TgLA) and ME49 isolate (TgMEA) were used to detect cross binding activities in F. gigantica experimental infected rabbit sera (FgIRS) and F. gigantica naturally infected bovine sera (FgIBS). The cross-binding activities in the prepared antisera were strongly directed towards FgA and TgLA rather than the other antigens. The characterization of the five antigens using SDS-PAGE showed 4 common bands of FgA and TgLA; 165, 97, 76, and 65 kDa. While two common bands were observed between TgRHA, TgMEA and FgA; 165, and 65 kDa. Whereas, two common bands found between three types of T. gondii antigens and FgEA were identified; 165 and 65 kDa. The immunogenic cross-reactive bands between FgA and TgLA with F. gigantica infected bovine sera were identified by immunoblot. In FgA, the common immunogenic bands were 165, 65 and 14 kDa. While in TgLA, common immunogenic bands were 165 and 65 kDa. Whereas, the common immunogenic band between FgA and TgLA identified with T. gondii experimentally infected sheep sera was 65 kDa. The current research proves cross reaction between F. gigantica and T. gondii. One common band of 65 kDa showed broad immunogenic cross-reactivity with the developed antisera raising the prospect of being putative common immunodiagnostic candidate of both infections.