IDIOTYPIC REPLICA OF A TOXOCARA-CANIS EXCRETORY-SECRETORY ANTIGEN EPITOPE

This study describes the production, characterization and use of an an ti-idiotype serum raised against the monoclonal antibody TC-1 which re cognizes a T. canis excretory/secretory antigen (ES Ag) epitope. Anti- idiotypic (anti-Id or Ab2) antibodies were produced in rabbits using T C-1 F(ab')(2) fragments; these anti-Id inhibited ES Ag binding to biot inylated TC-1, and also inhibited a larval microprecipitation assay us ing 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 followe d in the sera of BALB/c mice inoculated with embryonated eggs of T. ca nis during a 12-month infestation. A 3-week latency period was observe d before specific anti-TC-1 epitope antibodies were detected. High lev els were reached at 7 weeks post-inoculation with a maximum at the nin th month, and were then maintained until the end of the experiment. Th e results show the possible utility of anti-Id antibodies as an ES Ag molecular replica.