Assessment of Prion Inactivation by Fenton Reaction Using Protein Misfolding Cyclic Amplification and Bioassay

Inactivation of Template-Directed Misfolding of Infectious Prion Protein by Ozone

“…Increasing the concentration of hydrogen peroxide to 2.2 mol/liter reduced the contact time to 30 min for the same level of inactivation (17). Hydrogen peroxide inactivation (1.5 mol/liter) in the presence of Fe 2ϩ (15.7 mmol/liter) and heating at 50°C for 22 h was able to produce an approximately 6 log 10 reduction of prion infectivity (35). PrP Sc could also be degraded by Ն2.4 log 10 by photo-Fenton treatment (147 mmol/liter H 2 O 2 , 8.9 mmol/liter Fe 3ϩ ) after 5 h of UV-A exposure (25) and be degraded by Ն2 log 10 by titanium dioxide photocatalysis (25 mmol/liter titanium dioxide, 118 mmol/liter H 2 O 2 ) after 12 h of UV-A exposure (26).…”

“…Direct oxidation of protein targets by molecular ozone predominates reaction kinetics at lower pH, as indirect oxidative byproducts (i.e., hydroxyl radical generation) comprise a minor component of the oxidative potential at low pH (7). High inactivation rates of ozone at more acidic pHs have also been observed for Escherichia coli (35), norovirus (19) and helminth eggs (43). We are currently addressing what effects molecular ozone and its oxidative derivatives (OH .…”

“…However, the UV-ozone system studied by Johnson et al (14) produced limited ozone, thus generating limited hydroxyl radicals, requiring exposure times up to several weeks, and questioning the practicality of using UV-generated ozone as a decontamination/sterilizing approach to prion inactivation. Prion inactivation has also been studied with other advanced oxidation methods, such as the use of copper and hydrogen peroxide (17,34), iron and hydrogen peroxide (35), photo-Fenton treatment (25), and titanium dioxide photocatalysis (26). Hydrogen peroxide inactivation (100 mmol/liter) in the presence of copper (0.5 mmol/liter) was reported to achieve Ն5.2 log 10 inactivation of 263K scrapie prion with a contact time of 2 h at room temperature (34).…”

“…Although certain advanced oxidation processes have been shown to inactivate infectious prions (14,25,26,34,35), several major knowledge gaps exist; in particular, knowledge concerning how interactions between oxidant reaction conditions (e.g., temperature, pH, duration of exposure, ozone dose, and organic load) affect inactivation levels of prions is lacking. Consequently, the derivation of a concentration-time (CT) disinfection value for prions has never been reported.…”

Kinetics of Ozone Inactivation of Infectious Prion Protein

“…Ozone inactivation of Giardia lamblia at pH 7 (45), Naegleria gruberi at pH 7 (45), Cryptosporidium at pH 6 to 8 (41,42), and Bacillus subtilis spores at pH 7 (48) was higher as temperature increased toward 25°C, which is consistent with ozone inactivation of PrP Sc observed in this study. Inactivation of prions by other oxidants has also been examined in various studies (23,(54)(55)(56)(57)(58)(59)(60)(61). Chlorine and hydroxyl radicals are the primary oxidants in these studies.…”