Production of monoclonal antibody against Toxocara cati second-stage larvae and its application for the detection of circulating antigens.

Toxocariasis is an important zoonotic disease caused by the second-stage larvae of Toxocara species. Human toxocariasis is usually diagnosed by serological methods. We prepared monoclonal antibody specific for Toxocara cati (T. cati) and performed the following experiments using this antibody to increase the sensitivity of our capture ELISA for antigen detection. The isotype of monoclonal antibody was IgG3. Using this monoclonal antibody, a capture ELISA was developed. The produced monoclonal antibody reacted well with excretory-secretory (ES) antigen of T. cati with protein nature but not with other T. cati related antigens. A monoclonal antibody was raised against ES antigen of T. cati larval stage. No cross-reaction was found with antigens of Ascaris suum, Dirofilaria immitis, Trichostrongylus orientalis, encysted larvae of Trichinella spiralis, and metacercariae of Centrocestus armatus. The system had enough sensitivity to detect 5 ng/mL of circulating antigens in the serum. The results indicate that the new antigen detection system provides a useful method for the diagnosis of visceral and ocular larva migrans caused by T. cati and fulfils the requirements of a serological method for diagnosis of toxocariasis.