Molecular cloning and characterization of Schistosoma japonicum aldose reductase.

Antioxidant defense is an essential mechanism for schistosomes to cope with damage from host immune-generated reactive oxygen species. The evaluation of the effects of aldose reductase, an important enzyme that may be involved in this system, has long been neglected. In the present study, aldose reductase of Schistosoma japonicum (SjAR) was cloned and characterized. The activity of SjAR was assessed in vitro and was suppressed by the reported inhibitor, epalrestat. RT-PCR analysis revealed that SjAR was expressed at each of the development stages analyzed with increased levels in cercariae. The results also showed that SjAR was expressed at higher levels in adult male worms than in adult female worms. Indirect enzyme-linked immunosorbent assay and western blot analysis indicated that the purified recombinant SjAR (rSjAR) protein displayed a significant level of antigenicity. Immunolocalization analysis revealed that SjAR was mainly distributed in the gynecophoral canal of adult male worms. BALB/c mice immunized with rSjAR induced a 32.91 % worm reduction compared to the adjuvant group (P < 0.01). Moreover, a 28.27 % reduction in egg development in the liver (P > 0.05) and a 42.75 % reduction in egg development in the fecal samples (P < 0.05) were also observed. These results suggested that SjAR may be a potential new drug target or vaccine candidate for schistosomes.