Identification of a 26-kDa protein fraction as an important antigen for application in the immunodiagnosis of strongyloidiasis.

Strongyloidiasis caused by the intestinal nematode Strongyloides stercoralis typically occurs in the asymptomatic form. The definitive diagnosis is usually done by detection of larvae on fecal samples. However, as the parasite load is often low in most cases, microscopy is not usually sensitive and specific, and diagnosis becomes extremely difficult. Thus, development of reliable serological methods is imperative. In the present study, a diversity of epitopes from S. stercoralis larva were characterized by analysis of reactivity with serum samples obtained from individuals with and without the infection by using Western blot technique. A total of 91 serum samples belonging to 5 groups were analyzed. Different reactivity profiles were observed, representing recognition of proteins with molecular mass varied from 6 to 129 kDa. A protein band of approximately 26 kDa presented a high frequency of reactivity with serum samples from the strongyloidiasis patients group (18/23). Reactivity with this protein band was also observed in only 7 of 64 non-infected individuals or individuals infected with other helminthes. Reactivity with 2 other bands, 1 of approximately 33 kDa and a duplet of approximately 21 kDa, were also found in high frequency (17/23 and 9/23, respectively). However, reactivity with these bands was also observed in all the other serum groups studied. The results indicate that the 26-kDa band maybe be an important tool for the development of diagnostic techniques for strongyloidiasis.

Evaluation of an antigen from Taenia crassiceps cysticercus for the serodiagnosis of neurocysticercosis.

We report here the evaluation of an antigen from Taenia crassiceps cysticercus as a potential reagent in an enzyme-immunoelectrotransfer blotting assay (EITB) and an enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of neurocysticercosis (NC) using clinical specimens obtained from patients in different phases of the disease. Serum and cerebrospinal fluid (CSF) samples from 64 patients suspected of having NC according to clinical manifestation and brain computed tomography were tested by ELISA with Taenia solium total saline antigen (ELISA-Tso) and by immunoblotting with T. crassiceps glycoproteins antigen (EITB-gpTcra). Forty-five serum samples were also tested immunoblotting with T. solium glycoproteins antigen (EITB-gpTso) and 30 were tested by ELISA with T. crassiceps 14 kDa glycoprotein (ELISA-gp14Tcra). Serum samples from apparently healthy individuals without any parasitic disease and from patients with other parasitic diseases were included as controls. The results of ELISA-Tso analysis with CSF obtained from 64 patients with NC showed that 53 (83%) were reactive. EITB-gpTcra analysis with serum from the same group of patients showed a sensitivity of 91%. Results of EITB-gpTso and EITB-gpTcra analysis with serum samples demonstrated an agreement of 100% between both tests. ELISA-gp14Tcra was positive in 23 (77%) sera, 22 with paired CSF positive. When ELISA-gp14Tcra results were compared to EITB-Tso results, a relative sensitivity of 95% was observed. All serum samples from the control group were negative in ELISA-gp14Tcra and only one serum from an individual with Taenia saginata was reactive in this assay, showing a specificity of 99% for ELISA-gp14Tcra. This fraction was purified in only one step with a good yield for use in immunoassays. We suggest that the gp14Tcra antigen can be used for detecting anti-cysticercus antibodies in serum samples for epidemiological investigation purposes and also for diagnostic screening of NC patients.