The 33.1 kDa Excretory/secretory Protein Produced by Larvae Serves as a Potential Common Biomarker for Serodiagnosis of Toxocariasis in Paratenic Animals and Human.

Background: Toxocariasis is a prevalent zoonosis disease caused by the closely related nematode species and which parasitise Canidae and Felidae respectively. In paratenic hosts, larvae of these worms cause multiple organ damage. However, how these paratenic hosts response to these worms and whether any common biomarker can be applied for diagnosis are still unclear.

Methods: Excreted/secreted (E/S) antigens were prepared by culture of larvae in vitro. Using a western blot (WB) assay the humoral IgG responses, induced by spp. larvae to the worm's E/S antigens in different infected hosts including mice, rabbits and human, were examined.

Results: In a mouse model of toxocariasis, intraperitoneal injection of larvae induces inflammatory leukocyte accumulation in the liver and the lungs but not in the brain, although a remarkable number of larvae were detected in this organ. Mice and rabbits responded differently to spp. resulting in distinct heterogenous WB band patterns. Mice and rabbits both responded to a 33.1 kDa E/S constituent that turned out to be the most sensitive protein for serodiagnosis. Sera from human toxocariasis patients showed heterogenous WB band patterns similar to those observed in rabbits and all responded to the 33.1 kDa band.

Conclusion: 33.1 kDa E/S protein can be considered as a critical common biomarker for toxocariasis immuno-diagnosis in both paratenic animals and human and its specificity requires further investigation.