Elucidating the Functional Role of Tick Thioredoxin Reductase (TrxR)

Ticks experience a variety of oxidative stress conditions while on and off the vertebrate host. To counter-act the deleterious effects of reactive oxygen species, ticks utilized various antioxidant systems. Trx-TrxR maintains redox balance in the tick acting as electron donor system. In this study, we determined the transcriptional gene level expression of TrxR in unfed and across the blood meal cycle which revealed its importance during unfed and feeding stages in <i> Amblyomma maculatum</i>. In order to assess the functional significance of this highly conserved system, we utilized RNA interference to selectively deplete TrxR transcripts in vivo. Both transcriptional gene expression and enzymatic activity studies confirmed the successful depletion of transcript and activity, respectively. However, no significant effect was observed on total tick engorgement likely due to high redundancies and multiple back-ups in the redox system to ensure successful blood feeding upon loss of one individual component. This work opens new avenues of research in oxidative stress within tick vectors.