@article{tung-thompson_gentry-shields_fraser_jaykus_2015, title={Persistence of Human Norovirus RT-qPCR Signals in Simulated Gastric Fluid}, volume={7}, ISSN={["1867-0342"]}, DOI={10.1007/s12560-014-9170-4}, abstractNote={Human noroviruses (HuNoV) are a leading cause of foodborne disease and are known to be environmentally persistent. Foods usually become contaminated by contact with fecal material, both on hands and on surfaces. Emerging evidence suggests that HuNoVs are also shed and potentially aerosolized during projectile vomiting, resulting in another source of contamination. The purpose of this study was to compare the persistence of HuNoV in vomitus-like material (simulated gastric fluid, SGF, pH 2.5) to that in a pH neutral buffer (phosphate buffered saline, PBS, pH 7.4) in suspension and on surfaces. Human fecal suspensions containing two HuNoV strains (GI.1 and GII.4) were suspended in SGF and PBS. Suspension and surface samples were held at room temperature, and subsamples were collected from both samples for a period up to 42 days. Subsamples were subjected to RNA isolation, with and without inclusion of an RNase pre-treatment, followed by RT-qPCR amplification. In suspension assays, the genome copy number of HuNoV GII.4 decreased by ≤1.0-1.3 log10 over 42 days, irrespective of suspension buffer. On stainless steel, there was virtually no reduction in HuNoV GII.4 RT-qPCR signal over the 42-days experimental period, regardless of suspension buffer. Overall, the GI.1 RT-qPCR signal dropped more precipitously. In most cases, there were no statistically significant differences (p > 0.05) between persistence in solution or on surfaces when comparing RT-qPCR assays with and without prior RNase treatment. This study suggests that HuNoV suspended in vomitus-like material can persist for long periods, a likely contributor to foodborne transmission.}, number={1}, journal={FOOD AND ENVIRONMENTAL VIROLOGY}, author={Tung-Thompson, Grace and Gentry-Shields, Jennifer and Fraser, Angela and Jaykus, Lee-Ann}, year={2015}, month={Mar}, pages={32–40} }
 @article{tung_macinga_arbogast_jaykus_2013, title={Efficacy of Commonly Used Disinfectants for Inactivation of Human Noroviruses and Their Surrogates}, volume={76}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028x.jfp-12-532}, abstractNote={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.}, number={7}, journal={JOURNAL OF FOOD PROTECTION}, author={Tung, Grace and Macinga, David and Arbogast, James and Jaykus, Lee-Ann}, year={2013}, month={Jul}, pages={1210–1217} }