The serodiagnostic potential of recombinant proteins TES-30 and TES-120 in an indirect ELISA in the diagnosis of toxocariasis in cattle, horses, and sheep

Abstract

Toxocariasis is a zoonotic disease that affects humans and animals alike. Although recombinant proteins are widely used for its diagnosis in humans, their performance in companion and production animals remains unknown. This study aimed to investigate the serodiagnostic potential of the recombinant proteins rTES-30 and rTES-120 from Toxocara canis in an indirect ELISA for cattle, horses, and sheep. Serum samples collected from the animals were tested with indirect ELISA and Western Blotting using T. canis TES-30 and TES-120 recombinant proteins produced in Escherichia coli, as well as native-TES. In the ELISA, rTES-30 showed high serodiagnostic potential in sheep and horses (92.6% and 85.2%, respectively), while the sensitivity of rTES-120 was higher in cattle and horses (97.2% and 92.6%, respectively). Furthermore, a highly positive association was observed between native and recombinant proteins in seropositive samples, while a moderately positive association was observed in seronegative samples, probably due to the lower specificity of native TES. In conclusion, our study indicates that the use of recombinant proteins in an indirect ELISA is an effective tool for the serodiagnosis of toxocariasis in animals, with the choice of protein being species-dependent.

Fig 1

(A) Bovine ELISA close to cut-off confirmation via WB assay. Lane 1: PageRuler™ Pre-stained Protein Ladder (Thermo Fisher Scientific, USA); Lane 2: rTES–30 with pooled sera from four seropositive animals; Lane 3: rTES–120 with pooled sera from four seropositive animals; Lane 4: rTES–30 with pooled sera from four seronegative animals; Lane 5: rTES–120 with pooled sera from four seronegative animals. (B) Horse ELISA close to cut-off, confirmed by the WB assay. Lane 1: rTES–30 with pooled sera from four seropositive animals; Lane 2: rTES–120 with pooled sera from four seropositive animals; Lane 3: rTES–30 with pooled sera from four seronegative animals; Lane 4: rTES–120 with sera from four seronegative animals; (C) Sheep ELISA close to cut-off, confirmed by the WB assay. Lane 1: rTES–30 with pooled sera from four seropositive animals; Lane 2: rTES–120 with pooled sera from four seropositive animals; Lane 3: rTES–30 with pooled sera from four seronegative animals; Lane 4: rTES–120 with pooled sera from four seronegative animals.