This study evaluates five synthetic peptides derived from four, potentially protective, Taenia saginata oncosphere molecules for the serodiagnosis of T. solium cysticercosis/neurocysticercosis in three distinct Venezuelan endemic regions. The peptides, all of which have been described previously, are designated HP6-3, Ts45W-1, Ts45W-5, Ts45S-10 and TEG-1. In clinically verified and seropositive hospital cases, combining the results of three of the individual peptide-based ELISAs (HP6-3, Ts45W-1 and Ts45W-5) afforded the best balance between sensitivity (85%) and specificity (83.5%), a significant improvement on the 63.6% specificity obtained with the routinely employed T. solium cyst-fluid-based ELISA. Similarly, in the seropositive Venezuelan endemic zone samples, 89.09% of Amerindians, 77.27% of symptomatic rural subjects and 67.83% of non-symptomatic rural subjects were also classed as seropositive by the combined peptide-based ELISAs. The profile of antibody recognition to individual peptides varied between the different groups of samples examined. The relevance of the above findings for the serology and prognosis of T. solium cysticercosis/neurocysticercosis in hospital- and field-based situations is discussed.

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With the objective of providing inexpensive and reproducible assays for the detection of antibodies indicating exposure to Taenia saginata and Taenia solium, we have evaluated the diagnostic utility of the T. saginata oncosphere adhesion protein (HP6-Tsag), expressed in baculovirus (HP6-Bac) and bacteria (HP6-GST [glutathione S-transferase]), employing enzyme-linked immunosorbent assays (ELISAs) and sera from T. saginata infected cattle, T. solium infected pigs and serum and cerebrospinal fluid (CSF) samples from clinically defined T. solium neurocysticercosis (NCC) patients. The two recombinant proteins were antigenic in all three systems, with the signal to background ratio of the HP6-Bac ELISA slightly higher than that for the HP6-GST ELISA. Assay performance in cattle was similar to previously described peptide-based ELISA assays, although NCC sample sensitivity/specificity was marginally better. The sensitivity of the HP6-Bac and HP6-GST ELISAs was close for active human NCC (77.4 and 80.6% for serum and 76.9 and 73.1% for CSF samples, respectively). In inactive human NCC, however, the sensitivity of the HP6-Bac ELISA was almost twice that of the HP6-GST ELISA. Because peptides are relatively expensive and recombinant proteins are simple and economical to produce, the latter may provide useful reagents for antibody detection in countries with endemic cysticercosis/NCC.

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Abstract. This study examined the seroprevalence and serum antibody isotype profile for Taenia solium cysticercosis in an Amerindian community in the Amazonas state of Venezuela. An antigen-trapping enzyme-linked immunosorbent assay (Ag-ELISA) was used to detect viable cysticercosis. Indirect ELISA (Ab-ELISA) and enzyme-linked immunoelectrotransfer blot (EITB) was performed by using antigens prepared from T. solium metacestodes to detect anti-parasite antibodies. The Ag-ELISA and Ab-ELISAs revealed 64.7% and 79.0% seropositivity, respectively, in the Amerindian population. Immunoglobulin (Ig) M was the predominant antibody class, suggesting recent infection. In comparison sera from, clinically defined, hospital neurocysticercosis cases revealed only 27% seropositivity by Ag-ELISA, compared with 86-92% seropositivity by Ab-ELISA, and IgG 4 was the predominant antibody subclass detected. The EITB antigen recognition patterns of the hospitalized patients were very similar to that of the Amerindians, confirming exposure to the parasite. These results, combined with the predominance of IgM antibody responses and the marked detection of secreted products of viable parasites, strongly suggest that recent exposure to T. solium had occurred in the Amerindian population.

A serological study was undertaken in 1998 to evaluate levels of Taenia solium cysticercosis in 3 rural Venezuelan communities. Infection with viable metacestodes was diagnosed with a trapping enzyme-linked immunosorbent assay (ELISA) that detects a secreted product of viable parasites. Anti-metacestode antibodies were assayed by ELISA using T. solium vesicular fluid as antigen. A total of 1254 sera was collected from 3 communities (Canoabo, Sanare, and Rio Tocuyo) where previous studies had suggested the presence of T. solium. Our results demonstrate an unusually high seroprevalence of cysticercosis, indicating an attendant risk of transmitting the disease to other areas. The seroprevalence of infection with viable cysts, as indicated by detection of circulating parasite antigen, was 9.1% in Canoabo, 6.1% in Sanare, and 5.7% in Rio Tocuyo. The corresponding frequency of antibodies to T. solium cyst antigens was 36.5% in Canoabo, 36.5% in Sanare, and 4% in Rio Tocuyo. As these communities are probably representative of many others in Venezuela, T. solium cysticercosis may be a significant public health problem and more work is certainly indicated. An important finding was that local knowledge of the disease and its transmission do not necessarily guarantee diminished disease prevalence, indicating a lack of appropriate vigilance towards disease control.

A lambdaZAP-express cDNA library of Taenia saginata metacestodes was constructed. Antibody screening yielded a clone with an insert of 3,408 bp, an open reading frame of 2,589 bp, a deduced sequence of 863 amino acid and a molecular mass of 98.89 kDa. Alignments of the predicted amino acid sequence showed identity with paramyosins from several species: 98.8% with Taenia solium, 96.3% with Echinococcus.granulosus and about 70% with Schistosoma spp. The insert was expressed and purified. A collagen binding assay was performed which showed that T. saginata GST-paramyosin retained this property in a dose-dependent manner. Problems were encountered due to high backgrounds in serological assays in the homologous T. saginata system. However, the recombinant paramyosin was recognized by antibodies present in 31.6% of sera from T. solium seropositive cysticercosis patients and 100% of the sera from acute cysticercosis patients. The immunodominant epitope was the carboxyl-terminal fragment of the molecule.