Assessment of crude antigens extracted from Toxocara canis adult worms for sero-diagnosis of toxocariasis in animals and patients

Abstract

Toxocariasis is zoonosis disease caused by infection with Toxocara canis and/or Toxocara cati that parasitise Canidae and Felidae respectively. In paratenic hosts Toxocara larvae are limited in the second stage and remain in tissues. Diagnosis of toxocariasis is therefore mainly depended on detection of specific antibodies in the circulation. Different T. canis derived antigens, including excretory/secretory antigens produced by larvae, crude antigens extracted from larvae and crude antigens extracted from adult worms, have been applied in sero-diagnosis. The two formers have been intensively studied but the last is not fully understood. In this study, crude antigens extracted from adult worms and their organs were explored for sero-diagnosis of toxocariasis by a western blot assay. Our data showed that adult worm’s crude antigens made several pseudo-positive reactions with IgG antibodies in uninfected mice and it is unable to discriminate infected from T. canis uninfected mice. Analysis of isolated reproductive compartments showed that vas deferens and seminal vesicles of male reproductive system contain three low molecular weight proteins which strongly contribute to the formation of pseudo-positive reactions. These observations were also found in rabbits and human. We conclude that crude antigens extracted from adult worms are likely unable to be used in sero-diagnosis of toxocariasis in both animals and human.