Abstract: Objective To inhibit the expression of the target genes of peroxiredoxin （Prx） and thioredoxin reductase （TrxR） by RNA interference and evaluate its effect on the growth of Trichomonas vaginalis. Methods Genomic DNA was extracted from cultured Trichomonas vaginalis with phenol-chloroform method and was transcribed to double stranded RNA （dsRNA）. Short interference RNAs （siRNA， 21-23 bp） synthesized by digestion of dsRNA with RNase Ⅲ and purified through filter cartridge， were transfected into the cells in three groups （A， B and C） to degrade the target genes of Prx， TrxR and Prx＋TrxR through siPORT lipid， respectively， and the untransfected was selected as a control （group D）. The levels of Prx and TrxR mRNA were determined 24 h and 48 h post-transfection by relative quantitative RT-PCR， and the growth of Trichomonas vaginalis was estimated under microscope 36 h post-transfection. Results Trichomonas vaginalis mRNA levels of Prx and TrxR decreased. Though the cell activity showed no significant difference （P＞0.05） in four groups as expected， a difference existed （P＜0.01）between the groups in the average of cells（7.2×107/L， 14.2×107/L， 3.8×107/L and 20.3×107/L in groups A， B， C and D respectively）. Conclusions RNA interference inhibits the expression of the genes of Prx and TrxR and extended Trichomonas vaginalis cells cycle considerably， but showed no influence on the cell activity.

Key words: Trichomonas vaginalis, RNA interference, Peroxiredoxin （Prx）, Thioredoxin reductase （TrxR）