The Western blot for cysticercosis, which uses lentil lectin purified glycoprotein (LLGP) antigens extracted from the metacestode of Taenia solium, has been the "gold standard" serodiagnostic assay since it was first described in 1989. We report that the diagnostic antigens at 14, 18, and 21 kDa, as well as some larger disulfide-bonded antigens, are actually all members of a very closely related family of proteins, the 8-kDa antigens. The genes for 18 unique, mature proteins have been identified. Nine of these were chemically synthesized and tested in an enzyme-linked immunosorbent assay with a battery of defined serum samples, including 32 cysticercosis-positive serum samples reactive with the 8-kDa antigens of LLGP on Western blotting, 34 serum samples from patients with other parasitic infections, and 15 normal human serum samples. One of the 8-kDa antigens, TsRS1, is 100% sensitive and 100% specific. TsRS1 will be one component of a cocktail of three to four synthetic or recombinant antigens, based on the diagnostic bands of the Western blot, which will be used for the serodiagnosis of cysticercosis.

Taeniasis diagnosis is an important step in the control and elimination of both cysticercosis and taeniasis. We report the development of 2 serological taeniasis diagnostic tests using recombinant antigens rES33 and rES38 expressed by baculovirus in insect cells in an EITB format. In laboratory testing with defined sera from nonendemic areas, rES33 has a sensitivity of 98% (n = 167) and a specificity of 99% (n = 310) (J index: 0.97); rES38 has a sensitivity of 99% (n = 146) and a specificity of 97% (n = 275) (J index: 0.96). Independent field testing in Peru showed 97% (n = 203) of the taeniasis sera were positive with rES33, and 100% of the nontaeniasis sera (n = 272) were negative with rES33; 98% (n = 198) of taeniasis sera were positive with rES38, and 91% (n = 274) of the nontaeniasis sera were negative with rES38. Among the Peruvian sera tested, 17 of 26 Peruvian Taenia saginata sera were false positive with rES38 test. Both tests were also examined with cysticercosis sera, with a positive rate ranging from 21% to 46%. rES33 and rES38 tests offer sensitive and specific diagnosis of taeniasis and easy sample collection through finger sticks that can be used in large-scale studies. They are currently being used in cysticercosis elimination programs in Peru.

The assay of choice for serological detection of cysticercosis in humans and pigs is the enzyme-linked immunoelectrotransfer blot (EITB), a Western blot assay that relies on the use of seven lentil-lectin-purified glycoproteins (LLGPs) derived from Taenia solium metacestodes. The EITB is has a sensitivity of 98% and a specificity of 100% in detecting cysticercosis, yet scarcity of native source material and the labor-intensive process of metacestode purification hinder its practicality. These limitations have necessitated the reproduction of the EITB antigens in synthetic forms. Four chemically synthesized LLGP antigens, TS14, TS18var1, TSRS1, and TSRS2var1, were assayed individually by enzyme-linked immunosorbent assay (ELISA) and Western blot for immunoreactivity against a large cohort of sera from clinically defined neurocysticercosis patients. The sensitivity and specificity of all four of these antigens using the ELISA format were well below the standards set by the LLGP EITB, whereas results of the Western blot format closely mirrored those of the LLGP EITB.

No abstract

Internal standard reference curves are used in enzyme-linked immunosorbent assay (ELISA) plates to control for inter- and intra-assay variance. To compare the diagnostic potential of multiple T. solium antigens on an unbiased, universal scale, we have created a standard curve using normal, human immunoglobulin G (hIgG). The hIgG curve is inexpensive and simple to prepare, and remains stable at 5 degrees C for at least one year, with a coefficient of variance of less than 10%. The hIgG standard curve has proven a critical tool for the comparison of several diagnostic antigens slated for assay development.