Molecular characterization and diagnostic value of Taenia solium low-molecular-weight antigen genes.

Neurocysticercosis (NCC) caused by infection with the larvae of Taenia solium is an important cause of neurological disease worldwide. In order to establish an enzyme-linked immunosorbent assay (ELISA) for this infection using recombinant proteins, we carried out molecular cloning and identified four candidates as diagnostic antigens (designated Ag1, Ag1V1, Ag2, and Ag2V1). Except for Ag2V1, these clones could encode a 7-kDa polypeptide, and Ag2V1 could encode a 10-kDa polypeptide. All of the clones were very similar. Except for Ag2V1, recombinant proteins were successfully expressed using an Escherichia coli expression system. Immunoblot analysis of NCC patient sera detected recombinant proteins, but because reactivity to recombinant Ag1 was too weak, Ag1 was not suitable as an immunodiagnostic antigen. So, Ag1V1 and Ag2 were chosen as ELISA antigens, and the Ag1V1/Ag2 chimeric protein was expressed. Of 49 serum samples from NCC patients confirmed to be seropositive by immunoblot analysis, 44 (89.7%) were positive by ELISA. No assays of serum samples from patients with other parasitic infections recognized the Ag1V1/Ag2 chimeric protein. The Ag1V1/Ag2 chimeric protein obtained in this study had a high value for differential immunodiagnosis.