Effects of hydrogen peroxide (H2O2)on Cryptosporidium parvum infection in vitro were studied in this paper, using an oocyst excystation assay, a cell culture model, and a free radical inhibition technique. H2O2 treatment at 500 and 1 000 μmol/L significantly inhibited excystation of bleach-treated oocysts (P＜0.01). Concentrations of H2O2 at 500 and 750 μmol/L resulted in a significant decrease in C. Parvum infection at 35.77% and 58.16% respectively, when compared with the untreated control at 48 hours postinoculation. Surprisingly, C. parvum infection were significantly increased by 22.21% to 39.33% following treatment with 50 (P＜0.01), 100 (P＜0.01) or 200 (P＜0.05) μmol/L H2O2, respectively. Stimulatory effect with treatment of 100 μmol/L H2O2 was most obvious, compared with the untreated control at 48 hours postinoculation. Effects of H2O2 on C. parvum at 24, 48 and 96 hours postinoculation were similar, the highest infection being infection at 48 hours postinoculation, with the maximum inhibitory effect being seen at 96 hours postinoculation. The stimulatory and inhibitory effects of H2O2 treatment on C. parvum infection were, to a certain extent, abolished in the presence of free radical scavengers, reduced glutathione or mannitol. These observations indicate that reactive oxygen species (ROS), such as H2O2, may play a role in the course of C. parvum infection. This is the first time to demonstrate a significant action of ROS in C. parvum infection in vitro.
展开▼
