sodium-hypochlorite and Caliciviridae-Infections

The porcine gastric mucin binding magnetic bead (PGM-MB) assay was used to evaluate the ability of chlorine, chlorine dioxide, peroxyacetic acid, hydrogen peroxide, and trisodium phosphate to inactivate human norovirus within 10% stool filtrate. One-minute free chlorine treatments at concentrations of 33 and 189 ppm reduced virus binding in the PGM-MB assay by 1.48 and 4.14 log₁₀, respectively, suggesting that chlorine is an efficient sanitizer for inactivation of human norovirus (HuNoV). Five minute treatments with 5% trisodium phosphate (pH~12) reduced HuNoV binding by 1.6 log₁₀, suggesting that TSP, or some other high pH buffer, could be used to treat food and food contact surfaces to reduce HuNoV. One minute treatments with 350 ppm chlorine dioxide dissolved in water did not reduce PGM-MB binding, suggesting that the sanitizer may not be suitable for HuNoV inactivation in liquid form. However a 60-min treatment with 350 ppm chlorine dioxide did reduce human norovirus by 2.8 log₁₀, indicating that chlorine dioxide had some, albeit limited, activity against HuNoV. Results also suggest that peroxyacetic acid has limited effectiveness against human norovirus, since 1-min treatments with up to 195 ppm reduced human norovirus binding by <1 log₁₀. Hydrogen peroxide (4%) treatment of up to 60 min resulted in minimal binding reduction (~0.1 log₁₀) suggesting that H₂O₂ is not a good liquid sanitizer for HuNoV. Overall this study suggests that HuNoV is remarkably resistant to several commonly used disinfectants and advocates for the use of chlorine (sodium hypochlorite) as a HuNoV disinfectant wherever possible.

Topics: Caliciviridae Infections; Chlorine; Chlorine Compounds; Disinfectants; Humans; Hydrogen Peroxide; Norovirus; Oxides; Peracetic Acid; Phosphates; Sodium Hypochlorite; Time; Virus Inactivation

Human noroviruses (HuNoVs) are the most common cause of acute viral gastroenteritis worldwide and are a leading cause of foodborne disease. Their environmental persistence and purported resistance to disinfection undoubtedly contribute to their success as foodborne disease agents. The purpose of this study was to compare the efficacy of three commonly used disinfectant active ingredients against representative HuNoV strains and cultivable surrogates. Ethanol (50, 70, and 90%), sodium hypochlorite (5, 75, 250, 500, and 1,000 ppm), and a quaternary ammonium compound blend (at 0.1×, 1.0×, and 10× concentrations) were evaluated against two norovirus (NoV) genogroup II strains (GII.2 and GII.4) and two surrogates (feline calicivirus [FCV] and murine norovirus [MNV-1]). Virucidal suspension assays (30-s exposure) were conducted in accordance with ASTM International standard E-1052. Virus inactivation was quantified using reverse transcription quantitative PCR targeting the ORFI-ORFII junction (HuNoV), the RNA polymerase region (MNV-1), or the ORFI region (FCV); infectivity assays were also performed for MNV-1 and FCV. The two HuNoV strains and FCV were relatively resistant to ethanol (<0.5 log inactivation) irrespective of concentration, but MNV-1 was much more susceptible (log inactivation, ∼2.0 log at higher ethanol concentrations). Both HuNoV strains were more resistant to hypochlorite than were either of the animal surrogates, with the human strains requiring ≥500 ppm of hypochlorite to achieve statistically significant reduction (≥3.0 log) in virus concentration. All four viruses were resistant to inactivation (<0.5-log reduction) using the quaternary ammonium compound formulation at all concentrations tested. This study is novel in that it clearly demonstrates the relative ineffectiveness of common active disinfectant ingredients against HuNoV and highlights the fact that the cultivable surrogates do not always mimic HuNoV strains.

Topics: Caliciviridae Infections; Colony Count, Microbial; Disinfectants; Disinfection; Dose-Response Relationship, Drug; Drug Resistance, Viral; Ethanol; Food Safety; Gastroenteritis; Humans; Norovirus; Quaternary Ammonium Compounds; Sodium Hypochlorite; Virus Inactivation

We evaluated the in vitro efficacy of weak acid hypochlorous solution (WAHS) against murine norovirus (MNV) by plaque assay and compared the efficacy with diluted NaOCl (Purelox) and 70% ethanol. WAHS was as effective as 70% ethanol and diluted Purelox for 0.5-min reactions. For 0.5-min reactions in the presence of mouse feces emulsion, the efficacy of WHAS and 1:600 diluted Purelox was decreased, reducing the virus titers by 2.3 and 2.6 log10, respectively, while 70% ethanol reduced the titer by more than 5 log10. However, WAHS showed more than 5 log10 reductions for the 5-min reaction even in the presence of feces emulsion. Since WAHS showed enough efficacy in inactivating MNV in vitro, we tried to eliminate MNV from MNV-infected mice by substituting WAHS for their drinking water. However, MNV was found to be positive in feces of mice drinking WAHS by an RT-nested PCR and plaque assay. To investigate whether hypochlorite-based disinfectants could prevent infection of a mouse with MNV, WAHS or 1:6,000 diluted Purelox was substituted for the drinking water of mice for 2 or 4 weeks, and then the mice were placed in a cage with an MNV-infected mouse. The supply of disinfectants was continued after cohabitation, but MNV was detected in the feces of all the mice at 1 week after cohabitation. In this study, we tried to eliminate and prevent MNV infection from mice by supplying hypochlorite-based disinfectants as an easy and low-cost method. Unfortunately, drinking disinfectants was ineffective, so it is important to keep the facility environment clean by use of effective disinfectants. Also, animals introduced into facilities should be tested as MNV free by quarantine and periodically confirmed as MNV free by microbiological monitoring.

Topics: Animals; Animals, Laboratory; Caliciviridae Infections; Disinfectants; Dose-Response Relationship, Drug; Drinking; Drug Resistance, Viral; Ethanol; Feces; Female; Gastroenteritis; Mice; Mice, Inbred ICR; Norovirus; Sodium Hypochlorite; Specific Pathogen-Free Organisms

We isolated a novel murine norovirus (MNV), MT30-2 strain, from feces of conventional mice in Japan to evaluate the virucidal activity of four antiseptics. The MNV MT30-2 strain was inactivated by as little as 0.2% (w/v) povidone-iodine (PVP-I) and 0.1% (w/v) sodium hypochlorite (NaOCl) treatment as determined by a novel plaque assay. Importantly, PVP-I reduced the MNV titer by 4 log(10) within 15 s of exposure. The other two antiseptics, benzethonium chloride (BEC) and chlorhexidine gluconate (CHG), did not reduce the MNV titer even when treatment lasted for 60 s. When the virus titer was reduced by PVP-I or NaOCl treatment, the amount of MNV RNA was not reduced, indicating that the presence of viral RNA was not related to the virucidal activity of the antiseptics. PVP-I and NaOCl will be useful in controlling the spread of MNV, which is a common problem in mice colonies. In this study, we isolated a novel MNV and newly revealed that two antiseptics (PVP-I and NaOCl) were able to inactivate MNV at low concentrations and in a short contact time.

Topics: Animals; Anti-Infective Agents, Local; Caliciviridae Infections; Cell Line; Feces; Japan; Male; Mice; Mice, Inbred ICR; Molecular Sequence Data; Norovirus; Phylogeny; Povidone-Iodine; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral; Sequence Analysis, RNA; Sodium Hypochlorite

Human noroviruses pose an emerging public health threat, and despite stringent control strategies, variant strains continue to spread and cause disease outbreaks. Routinely used chemical sanitizers, such as sodium hypochlorite though effective on food contact surfaces, require high concentrations to cause reduction in enteric viral titers. The aim of this study was to evaluate the efficacy of trisodium phosphate (TSP) against three human enteric virus surrogates, murine norovirus (MNV-1), feline calicivirus (FCV), and bacteriophage MS2 in comparison to routinely used sanitizers. Three concentrations of TSP (1%, 2%, and 5%) at different contact times (30 sec and 1 min) were evaluated against the surrogate viruses individually inoculated on formica coupons. Our results showed that 5% TSP was effective in obtaining a >or=6 log(10) PFU reduction for MNV-1, FCV, and MS2 after a contact time of only 30 sec or 1 min similar to 10% household bleach (0.6% sodium hypochlorite, 5000 ppm available chlorine) for high titers of FCV and MS2, and with approximately 5 log(10) reduction after either 30 sec or 1 min on low viral titers. However, 2% TSP for 1 min resulted in >or=6 log(10) PFU reduction for FCV and MS2, but only a 1.05 log(10) PFU reduction for MNV-1 at high titers, with similar results after 30 sec. Decreasing TSP levels to 1% reduced FCV by approximately 2.65 log(10) PFU, MS2 by 4.5 log(10) PFU at high titers, and no reduction for MNV-1 after 30-sec or 1 min contact. Glutaraldehyde (2%) reduced FCV and MNV-1 titers by approximately 6 log(10) PFU; however, MS2 was reduced by only 3.22 and 3.74 log(10) PFU after 30 sec and 1 min, respectively, while 70% ethanol was not effective in reducing the three viruses at either high or low titers at both contact times. Alternative control strategies using TSP with short contact times should benefit the food industry in reducing norovirus transmission.

Topics: Animals; Antiviral Agents; Caliciviridae Infections; Cats; Disinfectants; Ethanol; Food Handling; Foodborne Diseases; Gastroenteritis; Glutaral; Humans; Levivirus; Mice; Norovirus; Phosphates; Sodium Hypochlorite; Solutions; Viral Load