The third and final diagnostic antigen of the lentil lectin purified glycoproteins (LLGP) extracted from the larval stage of Taenia solium has been characterized, cloned, and expressed. T24 is an integral membrane protein that belongs to the tetraspanin superfamily. It migrates at a position corresponding to 24-kDa and as a homodimer at 42-kDa. Antibodies from cysticercosis patients recognize secondary structure epitopes that are dependent upon correctly formed disulfide bonds. A portion of T24, the large, extracellular loop domain, was expressed in an immunologically reactive form in insect cells. When tested in a Western blot assay with a large battery of serum samples, this protein, T24H, has a sensitivity of 94% (101/107), for detecting cases of cysticercosis with two or more viable cysts, and a specificity of 98% (284/290). The identification and expression of T24H sets the stage for the development of an ELISA suitable for testing single samples and for large-scale serosurveys that is not dependent upon the isolation and purification of antigens from parasite materials.
Bibliographical noteFunding Information:
We thank Lynne Garrison for her help in producing the antibodies to native T24 in goats and Heather W. Govert for her help in evaluating the expression of recombinant T24H. We also thank Tamie Ando for his efforts to predict the tertiary structure of T24H. This work was supported by ICIDR-NIH grant U01 AI35894, NIH NIAID TMRC grant 1 PO1 AI51976-01, Burroughs Wellcome grant 063109, and Bill & Melinda Gates foundation grant 23981.
- Diagnostic antigen
- Recombinant protein
- Taenia solium
- Western blot