Effects of hydrogen peroxide on in vitro infection of Cryptosporidium parvum

The effect of hydrogen peroxide, (H2O2) on Cryptosporidium parvum infection and the protective function of free radical scavengers were studied in cul tured bovine fallopian tubes epithelial cells. H2O2 treatment at 500 mu moL /L and 1 mmol/L significantly inhibited excystation of bleach-treated oocys ts (p < 0.01). At 48 h postinoculation, H2O2 at 500 and 750 mu mol/L result ed in a significant (p < 0.01) decrease of C. parvum infection by 35.77% an d 58.16% respectively in the cultured cells, when compared with the untreat ed control. Surprisingly, the infection was significantly increased from 22 .21% to 39.33% (p < 0.05) with lower concentration of H2O2 (50 similar to 2 00 mu moL/L). The inhibitory and stimulatory effects of H2O2 treatment on C . partum infection were, to a certain extent, abolished in the presence of reduced glutathione or mannitol. These observations indicate that reactive oxygen species, such as H2O2, may play an important role in C. parvum infec tion.