Evaluation of cross-reactivity to Taenia hydatigena and Echinococcus granulosus in the enzyme-linked immunoelectrotransfer blot assay for the diagnosis of porcine cysticercosis

Background: Taenia solium is an important zoonotic parasite that infects humans as definitive host (taeniasis) and pigs as intermediate host (cysticercosis). Serological diagnosis of porcine cysticercosis is limited to antigen detection using ELISA, which is known to cross-react with other Taenia species, and antibody detection using the lentil-lectin glycoprotein enzyme-linked immunoelectrotransfer blot (LLGP EITB), which has not been adequately evaluated for cross-reactivity to other parasites. Field studies suggest that the GP50 diagnostic band of the LLGP EITB may cross-react to Taenia hydatigena, a common non-zoonotic parasitic infection of pigs. The objective of this study was to evaluate the specificity of the LLGP EITB assay in pigs infected experimentally with T. hydatigena and Echinococcus granulosus. Results: Twelve three-month-old seronegative were divided into two groups; six were each given an oral challenge with a single gravid proglottid of T. hydatigena and the other six were each given an oral challenge with 50 gravid proglottids of E. granulosus. Serum samples were collected biweekly until 14 weeks when all pigs underwent a detailed necropsy. Taenia hydatigena cysticerci were found in two of six pigs from the first group. Four T. hydatigena-exposed pigs were seropositive at the GP50-band only on EITB LLGP; two of these had cysts at necropsy while no seronegative pigs had cysts. One E. granulosus-exposed pig was positive to EITB LLGP, again with reactivity only to GP50; all six pigs had hepatic echinococcosis on necropsy. Conclusion: These results provide definitive evidence that the GP50 diagnostic band in pigs cross-reacts with T. hydatigena. Evidence of cross-reaction with E. granulosus was not conclusive.