Characterization of Ozone Disinfection of Murine Norovirus

Abstract

Despite the importance of human noroviruses (NoVs) in public health, little information concerning the effectiveness of ozone against NoVs is available. We determined the efficacy of ozone disinfection using murine norovirus (MNV) as a surrogate of human NoV. MNV in ozone demand-free buffer was exposed to a predetermined dose of ozone at two different pHs and temperatures. The virus remaining in the solution was analyzed by plaque assay, real-time TaqMan reverse transcriptase PCR (RT-PCR) (short template), and long-template conventional RT-PCR. Under all conditions, more than 99% of the MNV was inactivated by ozone at 1 mg/liter within 2 min. Both RT-PCR assays significantly underestimated the inactivation of MNV, compared with that measured by plaque assay. Our results indicate that NoV may be more resistant to ozone than has been previously reported. Nevertheless, proper ozone disinfection practices can be used to easily control its transmission in water.Noroviruses (NoVs) are the major etiological agent of gastroenteritis in all age groups worldwide and are transmitted via a fecal-oral route (3,18,22,27,35). As important waterborne and food-borne pathogens, they are included on the U.S. EPA Contaminant Candidate List 3 (CCL 3) (7, 11). Water can be contaminated by NoV-containing feces released from either symptomatic or asymptomatic patients (26). High concentrations of the virus in fecal matter of infected people (ϳ10 9 viral particles/g of feces) (25), low infectious doses (Ͻ10 viral particles) (32), and high resistance to various environmental stresses (9, 21) contribute to the high prevalence of outbreaks caused by NoV. Proper disinfection of drinking and recreational water is necessary to prevent waterborne outbreaks (33).Among currently available analytical methods of virus cultivation, the plaque assay is the most convenient and commonly applied analytical method for determining virus inactivation by a disinfectant (6, 12). However, no conventional cultivation assays or convenient laboratory animal models have been available for human NoV. Thus, despite the importance of NoV in public health, limited information is available regarding the effectiveness of various disinfectants against NoV.Ozone (O 3 ), a strong oxidizing agent, has been widely used as a disinfectant in drinking water treatment plants in many European countries, receiving more attention after the discovery of potentially harmful chlorine by-products (37, 38). Owing to its high effectiveness and lack of residue after disinfection, ozone can be used for both surface and groundwater disinfection. Previously, a number of ozone disinfection studies of enteric viruses such as adenoviruses and enteroviruses have been reported (29,33). In all of these studies, ozone disinfection was determined by either plaque assay of feline calicivirus (FCV) or long-template (LT) reverse transcriptase PCR (RT-PCR) assay of human NoV. FCV, a member of the Caliciviridae family, is easily cultivated in vitro and has been commonly used as a surrogate of NoV (10, ...

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

“…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 .…”

“…Ozone as an advanced oxidation technology is widely used in water and wastewater treatment processes for inactivation of bacteria (44), viruses (19,39), and protozoa (18). 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.…”

“…The U.S. Environmental Protection Agency (USEPA) routinely uses a CT concept for characterizing disinfection requirements for microbial pathogens under a given set of reaction conditions (pH and temperature) and for which a comparative assessment of the susceptibility of the pathogens can be made (41,42). Consequently, the CT value is commonly used as an engineering target for inactivation of pathogens in water matrices, as a regulatory standard in water treatment, and for modeling the inactivation kinetics of physicochemical disinfectants (19,39).…”

Of Mice and Microflora

“…However, MNV is readily disinfected by chlorine or ozone in drinking water and, thus, is susceptible to inactivation by oxidizing disinfectants. 28,66 MNV has not been associated with clinical disease in immunecompetent mice. However, oral inoculation with a cultureadapted strain of MNV-1 (10 7 plaque-forming units) into 129S6/SvEv inbred mice results in very slight and transient granulocytic infiltration of the lamina propria of the duodenum at 24 hours post infection (without apoptosis of enterocytes) as well as mild increases in extramedullary hematopoiesis and lymphoid hyperplasia in the spleen.…”

Antiviral Properties of Silver Nanoparticles on a Magnetic Hybrid Colloid

“…For the RT-PCR assays, the viral genomes of MNV and AdV2 were extracted using a QIAamp MinElute virus spin kit (Qiagen, USA). RT-PCR for MNV was performed using a AgPath-ID one-step RT-PCR kit (Ambion, USA) as described previously (28). Briefly, the nucleic acids from MNV were reverse transcribed at 48°C for 30 min and denatured initially at 95°C for 10 min, followed by 45 cycles of 95°C for 15 s and 60°C for 1 min using a 7300 real-time PCR system (Applied Biosystems, USA).…”