Detection of circulating antigens in experimental anisakiasis by two-site enzyme-linked immunosorbent assay.

A two-site enzyme-linked immunosorbent assay (ELISA) based on the avidin-biotin system was developed to study circulating antigens in the sera of rats orally or intraperitoneally infected with L3 larvae of Anisakis simplex s.l. Somatic and excretory-secretory antigens were detected from 24 h post-infection in all infected rats. A direct relationship between the number of larvae inoculated and the concentration of antigens in the sera was demonstrated; however, the amount of antigen decreased with the course of the infection. Comparative analysis revealed that intraperitoneal inoculation is most appropriate for detecting excretory-secretory antigens in serum. The minimum concentrations of A. simplex antigen detectable were approximately 2.5 microg/ml for somatic and excretory-secretory antigens. This antigen detection assay may have application in the diagnosis of anisakiasis.