Characterization and enzymatic function of thioredoxin glutathione reductase in Orientobilharzia turkestanicum isolated from Xizang

Orientobilharziasis, caused by Orientobilharzia turkestanicum, is a zoonotic parasitic disease that leads to significant economic losses in livestock and cercarial dermatitis in humans. This study focuses on the molecular characterization and functional analysis of thioredoxin glutathione reductase (TGR) from O. turkestanicum, a key enzyme involved in the parasite’s antioxidant defense system. The full-length O. turkestanicum thioredoxin glutathione reductase (OtTGR) cDNA and O. turkestanicum thioredoxin glutathione reductase with selenocysteine (OtTGRsec) were cloned and expressed as recombinant proteins in E. coli. Western blotting confirmed the specific immunoreactivity of rOtTGR with polyclonal antibodies, and immunohistochemistry revealed its predominant localization on the tegument of adult worms. Enzymatic activity assays demonstrated that rOtTGRsec possesses thioredoxin reductase, glutaredoxin, and glutathione reductase activities, with optimal activity under physiological pH and temperature conditions. RNA interference assays showed that siRNA3 effectively suppressed OtTGR expression in vitro, reducing mRNA levels by 46.1%. These findings highlight the critical role of OtTGR in parasite survival. Comparative with other trematodes, such as Schistosoma japonicum and Fasciola hepatica, suggests that OtTGR may serve as a promising target for vaccine or drug development. Although immune-protective studies were not feasible due to host incompatibility, the conserved role of TGR across trematodes underscores its potential for controlling orientobilharziasis. Future studies will explore the immunogenicity and protective efficacy of OtTGR to assess its candidacy as a therapeutic target.