DETECTION OF CIRCULATING TOXOCARAL ANTIGENS IN DOGS BY SANDWICH ENZYME-IMMUNOASSAY

  • 1 January 1984
    • journal article
    • research article
    • Vol. 51  (3) , 609-613
Abstract
The presence of circulating toxocaral antigens (CTA) in the sera of dogs infected with Toxocara canis by using a sandwich enzyme-immunoassay (SEIA). A specificity of this assay with different antigens was observed, i.e., the EIA values, which express the antigen concentration, of excretory-secretory antigen from T. canis larvae were higher than those of other antigens (Ascaris lumbricoides, Dirofilaria immitis and Fasciola hepatica). The variability in intraassay was below 10%. In age distribution of CTA levels, the highest level was observed at 1 mo. of age. The levels decreased gradually until 6 mo. of age and then the same levels were maintained until adult age. Slightly elevated levels were found in the sera of fetuses. A significant correlation was obtained between age and CTA levels. The positive correlation between the number of worms and CTA levels was significant. As for the IgG, IgM and IgA antibodies, a significant correlation was observed between the IgM antibody activities and CTA levels, but this was not observed with IgG and IgA antibodies. The immunological response to T. canis infection in dogs may not be reached until 1 or 2 mo. after birth, although detectable CTA levels were observed in fetal and early life. Immunological stimulation for canine toxocariasis may be maintained by the excretory-secretory materials from the larvae through life and as a result. IgM antibody production may be observed even in chronically infected adult dogs. The SEIA technique reported may be useful as a diagnostic tool of human toxocariasis, since the CTA can be directly demonstrated by the technique.