Idiotypic replica of a Toxocara canis excretory/secretory antigen epitope

International Journal for Parasitology
R BardonC Aguila

Abstract

This study describes the production, characterization and use of an anti-idiotype serum raised against the monoclonal antibody TC-1 which recognizes a T. canis excretory/secretory antigen (ES Ag) epitope. Anti-idiotypic (anti-Id or Ab2) antibodies were produced in rabbits using TC-1 F(ab')2 fragments; these anti-Id inhibited ES Ag binding to biotinylated TC-1, and also inhibited a larval microprecipitation assay using TC-1. Assays show that the Ab2 beta or "internal image" of a T. canis ES Ag epitope was obtained. The antibodies have been used as an idiotypic copy of ES Ag in a diagnostic ELISA for murine toxocariosis. Affinity-purified anti-Id antibodies were used to raise a homologous anti-anti-Id (Ab3) response in rabbits. Antibody formation was followed in the sera of BALB/c mice inoculated with embryonated eggs of T. canis during a 12-month infestation. A 3-week latency period was observed before specific anti-TC-1 epitope antibodies were detected. High levels were reached at 7 weeks post-inoculation with a maximum at the ninth month, and were then maintained until the end of the experiment. The results show the possible utility of anti-Id antibodies as an ES Ag molecular replica.

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