A collaborative study on larval excretory/secretory antigens of Toxocara canis for the immunodiagnosis of human toxocariasis with ELISA.

Two batches of excretory/secretory (E/S) antigens from second stage larvae of Toxocara canis maintained in vitro were prepared independently in two different laboratories (Zürich and Basel) and analysed in order to obtain information for future efforts to standardize the enzyme-linked immunosorbent assay (ELISA) used for the serodiagnosis of human toxocariasis. SDS-PAGE and "Western-blotting" revealed at least 10 different antigenic components common to the two antigen preparations. However, distinct qualitative and quantitative differences among the two E/S-antigens were observed, since one antigen had a more complex composition than the other. Despite these differences, an accordance of serodiagnosis was obtained in 80% of 25 sera from patients with suspected Toxocara infection tested independently in two different ELISA systems (Basel and Zürich) with the corresponding E/S-antigens. The specificity was 93% as determined (BS-antigen, BS-ELISA) by testing 46 out of 3396 sera from patients with parasitologically proven extra-intestinal helminthic infections. Cross-reactions occurred mainly with sera from patients infected with filariae (5 from 13 cases) exhibiting very high extinction values in their homologous ELISA-system. The reproducibility (intra- and inter-test variations) of two ELISA systems using the corresponding E/S-antigens varied from 5-15%. The results demonstrate that T. canis E/S-antigens may well be applicable for standardization of the ELISA used for the serodiagnosis of human toxocariasis.

Application of the enzyme-linked immunosorbent assay (ELISA) for the diagnosis of filariasis and echinococcosis.

The Enzyme-Linked Immunosorbent Assay (ELISA) was compared with the Indirect Fluorescent Antibody Test (IFAT), the Indirect Haemagglutination Test (IHA) and Counter Immuno Electrophoresis (CIE) in the serological examination for filariasis and echinococcosis. The ELISA was the most sensitive but least specific method. The most striking phenomena were the cross-reactions observed when filariasis sera and E. granulosus hydatid fluid antigen were tested and vice versa, when echinococcosis sera were tested with D. viteae antigen. Crossreacting antibodies could be absorbed with the non-corresponding antigens. ELISA proved to be the most convenient test for the screening of large numbers of sera. For a specific diagnosis however it was nevertheless essential to test ELISA reactive sera with other methods.

[Use of an enzymatic immune method (ELISA) for the serodiagnosis of amebiasis]. / Anwendung einer Enzym-Immunmethode (ELISA) für die Serologie der Amöbiase.

The Enzyme Linked Immunosorbent Assay (ELISA) was compared with the indirect immunofluorescence antibody test (IFAT) and with the counter-immunoelectrophoresis (CIE) in the serology of amebiasis. In cases of liver abscesses, the ELISA was as sensitive as CIE, but slightly more sensitive than IFAT. In cases where the patient asymptomatically passed cysts of E. histolytica, none of the three tests was positive. As a routine laboratory screening test, the ELISA proved to be the most convenient of the three.