Identification of Excretory/Secretory Antigens Produced by L2 Stage Larvae of Toxocara canis Involving in Induction of IgG Response in Mice by Proteomics Approach

Toxocara canis is a kind of round worms that parasitise Canidae. Human and other animals are their paratenic hosts in which the worm is limited in the second larval stage and therefore they can’t complete their life cycle. In these paratenic hosts, excretory/secretory antigens (E/S-Ags) produced by T. canis larvae were shown involve in regulating immune response and inducing IgG production that in turn becomes protecting molecules and biomarkers for toxocariasis sero-diagnosis. In this study, a proteomics approach of 2D-gel electrophoresis and a western blotting assay were applied for determination of biomarkers derived from E/S-Ags of T. canis larvae that are recognized by IgG in infected mice. Our results showed that the majority constituents of E/S-Ags have pI at pH 9–10 and the minority one have pI at pH 4–8. Western blotting analysis showed that 33.1 kDa and 49.4 kDa E/S-Ags were strongly recognized by specific IgG in infected mice. We conclude that these 33.1 and 49.4 kDa constituents in E/S-Ags might be potential targets for protection of the host immune system as well as biomarkers for developing diagnosis products used in veterinary and human medicine.