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Abstract

To evaluate the reduction of human norovirus (HuNoV) by chlorine disinfection under typical drinking water treatment conditions. HuNoV, murine norovirus (MNV) and poliovirus type 1 (PV1) were inoculated into treated water before chlorination, collected from a drinking water treatment plant, and bench-scale free chlorine disinfection experiments were performed for two initial free chlorine concentrations, 0.1 and 0.5 mg l(-1). Inactivation of MNV reached more than 4 log(10) after 120 and 0.5 min contact time to chlorine at the initial free chlorine concentrations of 0.1 and 0.5 mg l(-1), respectively. MNV was inactivated faster than PV1, and there was no significant difference in the viral RNA reduction rate between HuNoV and MNV. The results suggest that appropriate water treatment process with chlorination can manage the risk of HuNoV infection via drinking water supply systems. The data obtained in this study would be useful for assessing or managing the risk of HuNoV infections from drinking water exposure.

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... In the absence of a cell culture method for NoVs, some cultivable surrogates have been widely studied; MNV-1, feline calicivirus (FCV), bacteriophage MS2, and (or) tulane virus have been widely used as a surrogate of human norovirus due to the absence of a cell culture method for NoVs (Bae and Schwab 2008;Cannon et al. 2006;Cromeans et al. 2014;Hirneisen et al. 2010;Hirneisen and Kniel 2013;Kitajima et al. 2010;Sinclair et al. 2012). Hirneisen and Kniel (2013) noted that one surrogate alone cannot fully mimic the characteristics of human norovirus stability in different treatments. ...
... They also suggest that several surrogates should be considered in the evaluation of disinfection treatments because the many different genogroups and genotypes of NoVs have different environmental responses. However, MNV-1 is generally accepted as a best surrogate for NoVs (Cannon et al. 2006;Cromeans et al. 2014;Kitajima et al. 2010;Wobus et al. 2006). Especially, Kitajima et al. (2010) reported that there was no significance in the overall viral RNA reduction rate between human norovirus and MNV-1, indicating similar persistence against free chlorine disinfection. ...
... However, MNV-1 is generally accepted as a best surrogate for NoVs (Cannon et al. 2006;Cromeans et al. 2014;Kitajima et al. 2010;Wobus et al. 2006). Especially, Kitajima et al. (2010) reported that there was no significance in the overall viral RNA reduction rate between human norovirus and MNV-1, indicating similar persistence against free chlorine disinfection. Based on these previous studies, we may speculate that the viricidal effects of combined chlorine and vitamin B 1 against NoVs could be similar to MNV-1. ...
Article
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This study investigated the synergistic effects of combined chlorine (200, 500, 700, and 1000 ppm) and vitamin B1 (1000, 2000, and 3000 ppm) on the murine norovirus-1 (MNV-1), a human norovirus (NoV) surrogate, on oyster surface. Vitamin B1 slightly reduced MNV-1 (0.04–0.3 log-reduction), whereas chlorine significantly reduced MNV-1 (0.4–1.0 log-reduction). The combined chlorine and vitamin B1 resulted in a 0.52–1.97 log-reduction of MNV-1. The synergistic reduction in the MNV titer was not dependent on the concentrations of chlorine and vitamin B1, and it ranged between 0.08 and 1.03 log10 PFU/mL. The largest synergistic reduction observed was for the combined 700 ppm chlorine and 1000 ppm vitamin B1. The pH and mechanical texture of the oysters were not significantly changed by the combined 0–1000 ppm chlorine and 3000 ppm vitamin B1. The overall sensory acceptability were significantly (P < 0.05) reduced in oysters treated with 1000 ppm chlorine and 3000 ppm vitamin B1 than in those treated with 0–700 ppm chlorine and 3000 ppm vitamin B1. This study suggests that the combined 700 ppm chlorine and 3000 ppm vitamin B1 could potentially be used to reduce NoV on oyster surface without causing concomitant changes in the mechanical texture, pH, or sensory qualities of the oysters.
... Coxsackie (Padalko et al., 2004). Au-delà d'une concentration critique établie à 9 531 µM purifiés (Kitajima et al., 2010;Sano et al., 2010;. Au contraire, le génome des NoV GII.4 non purifiés n'a été réduit que de 0,4 log10 pour un Ct de 2 500 mg.min.L -1 (Tung et al., 2013). ...
... HuNoVs" from human stool samples were more sensitive to chlorine disinfection than "untreated HuNoVs" for the same Ct value. For example, a 3.6 log10 reduction in genomes of "purified HuNoVs" was obtained for a Ct value of 15 mg.min.L -1 , while a 0.4 log10 reduction in genomes of "untreated HuNoVs" was reached for a Ct value of 250 mg.min.L -1 (Kitajima et al., 2010;Tung et al., 2013). The matrix effect promotes the persistence of HuNoVs during chlorine disinfection. ...
... Our results showed modifications of purified and complete HuNoV capsids in the whole range of CT values. As described previously, CT values ranging between 1 and 5 mg.min.L -1 led to a reduction of 1.0 to 2.0 log10 of genomes for purified HuNoVs(Kitajima et al., 2010;Sano et al., 2010;. Conversely, reduction of 0.4 log10 of genome for non-purified HuNoVs was observed using CT values of 2,500 mg.min.L -1(Tung et al., 2013). ...
Thesis
Les norovirus (NoV) sont l’une des principales causes de gastro-entérites dans le monde. La recherche des NoV dans les aliments et l’eau est réalisée à l’aide des techniques de biologie moléculaire mais elles présentent l’inconvénient de ne pas apporter d’information sur le caractère infectieux des virus. La détection du génome d’un virus capable de reconnaître préalablement son récepteur cellulaire pourrait limiter la surestimation du danger viral en excluant les particules non infectieuses n’ayant plus de capside intègre. Plusieurs études ont montré que l’interaction spécifique de la capside avec des antigènes tissulaires de groupes sanguins (HBGA) favorisait l’infection des NoV chez l’Homme. Ces sucres complexes, retrouvés dans la salive et à la surface des cellules intestinales, sont considérés comme des facteurs d’attachement mais il n’est pas exclu qu’ils puissent jouer un rôle de (co)-récepteur cellulaire ou un rôle de protection des NoV vis-à-vis des stress imposés par le système digestif de l’Homme avant d’atteindre sa cellule hôte. Dans un premier temps, des facteurs d’inactivation que les virus sont susceptibles de rencontrer avant leur arrivée dans l’intestin de l’Homme (i.e. pH acide, enzymes protéolytiques) ont été testés pour évaluer le rôle de protection des NoV par les HBGA. Dans un second temps, des traitements d’inactivation (i.e. vieillissement naturel, chaleur, oxydants) ont été testés pour évaluer le maintien de la fixation des HBGA par les capsides de NoV GII.4, et donc de l’intégrité de la capside virale. Par des approches méthodologiques complémentaires, il a été montré que l’interaction avec les HBGA ne protégeait pas les NoV GII.4 vis-à-vis du pH acide et des enzymes protéolytiques. Ensuite, nos résultats ont mis en évidence que la fixation spécifique des NoV aux HBGA permettait de sélectionner les virus possédant encore des capsides structurées. Cependant, cette approche montre certaines limites lorsque les traitements induisent des modifications mineures au niveau de la capside, suggérant que la perte de la fixation des HBGA par les capsides ne puisse pas toujours être corrélée à la perte du caractère infectieux des NoV.
... Seven studies were excluded owing to the reporting of RT-qPCR data alone and an absence of comparative surrogate infectivity and RT-qPCR data; 3 citations were excluded owing to the use of semi-quantitative conventional end point RT-PCR. Two additional studies were rejected, one owing to limited hNoV data, (Kitajima et al., 2010) and another because it was a review article where some of the data sources were duplicated (Bertrand et al., 2012). ...
... Consequently, we directly compared RT-qPCR and infectivity data from surrogates to hNoV RT-qPCR data for key treatments (excluding studies that reported on surrogates alone or hNoV RT-qPCR data alone). Data were extracted NASBA Nowak et al. (2011b) Disinfectants and sanitizers in solution hNoV RT-qPCR data only Liu et al. (2010) Liquid soap and hand sanitizers on contaminated hands hNoV RT-qPCR data only Liu et al. (2011) Alcohol based hand rubs hNoV RT-qPCR data only Mormann et al. (2010) Reduction in RT-qPCR signals following food processing conditions hNoV RT-qPCR data only Ngazoa et al. (2008) Attachment to stainless steel and household disinfection hNoV RT-qPCR data only Richards et al. (2012) Freezing and thawing and capsid integrity hNoV RT-qPCR data only D' Souza et al. (2006) Persistence on stainless steel, ceramic and formica and transfer to lettuce Qualitative RT-PCR Hudson et al. (2007) Ozone fog disinfection of surfaces Qualitative RT-PCR Barker et al. (2004) Cleaning and decontamination study Qualitative RT-PCR Bertrand et al. (2012) Review paper Avoidance of duplication Kitajima et al (2010) Chlorine inactivation in water. hNoV data was limited by the scale of the study. ...
Article
Human noroviruses (hNoV) are the single largest cause of acute gastroenteritis in the western world. The efficacy of hNoV control measures remains largely unknown, partly owing to the inability to grow the virus in vitro and partly to the large number of surrogate studies of unknown relevance. A systematic review of the persistence and survival of hNoV in foods and the environment was undertaken based upon PRISMA (preferred reporting items for systematic reviews and meta analyses) guidelines to answer the questions: (1) "What are the natural hNoV persistence characteristics in food and the environment?" and (2) "How can these properties be altered by applying physical and/or chemical treatments to foods or food contact surfaces?" Over 10,000 citations were screened using defined inclusion and exclusion criteria. One hundred and twenty-six (126) citations were identified for further evaluation and data were extracted based upon the conditions of study and treatment (e.g., treatment parameters, pH, and temperature, time, infectivity, and RT-qPCR results). Since the only markers for hNoV persistence and survival were RT-qPCR data and human challenge studies, citations for further analysis were restricted to only those that included data on hNoV behavior (using RT-qPCR) as compared directly to surrogate virus behavior (using both RT-qPCR and infectivity) in the same study, and clinical studies. Based on these criteria, a total of 12 independent studies (5 for thermal inactivation and 7 for available chlorine) and 3 human challenge studies were identified. RT-qPCR always underestimated reductions in surrogate virus titre as a function of treatment when compared to infectivity. The corresponding reductions in RT-qPCR signals for hNoV under comparable conditions were nearly always less than those observed for the surrogates. These relationships were statistically significant for heat when comparing persistence of hNoV RT-qPCR signals with surrogate MNV-1 RT-qPCR signals (P equal persistence=<0.07); and for free chlorine when comparing persistence of hNoV RT-qPCR signals to those of FCV F-9 (p=<0.01). Overall the data suggest that hNoV are frequently more resistant to typical food and environmental control measures compared with cultivable surrogate viruses, when basing data on comparative RT-qPCR results.
... log after exposure to 1 mg liter À1 free chlorine for 5 and 15 min, respectively, and oxidative damage to the virus capsid was also observed (86). Used against NoV in suspension, sodium hypochlorite at concentrations of 0.5 ppm was able to reduce NoV GII.4 GE by~1 log after 5 min,~2 log after 10 min, and~3.6 log after 30 min of exposure (38) and, at 160 ppm and above, was able to reduce the GI GE titer by 5 log (53). Tung et al. (100) reported no significant reduction in NoV GII.2 GE after 30 s of exposure to hypochlorite concentrations 1,000 ppm; GII.4 GE also was not significantly reduced at concentrations 500 ppm but was reduced by .4 ...
... In a volunteer study, treatment of water with 10 mg Àl of chlorine for 30 min (reportedly 5 to 6 mg ml À1 free chlorine) prevented infection of volunteers (35). Other studies evaluated the effectiveness of chlorine or sodium hypochlorite to reduce NoV RNA, with generally good results (19,36,38,53,92). Chlorine solutions were also effective as a surface disinfectant for steel, melamine, berries, and herbs (6,9,27,73,98). ...
Article
This critical review addresses the persistence of human norovirus (NoV) in water, shellfish, and processed meats; on berries, herbs, vegetables, fruits, and salads; and on food contact surfaces. The review focuses on studies using NoV; information from studies involving only surrogates is not included. It also addresses NoV elimination or inactivation by various chemical, physical, or processing treatments. In most studies, persistence or elimination was determined by detection and quantification of the viral genome, although improved methods for determining infectivity have been proposed. NoV persisted for 60 to 728 days in water, depending on water source. It also persisted on berries, vegetables, and fruit, often showing 8.0, freeze-drying, and UV radiation. Ineffective disinfectants included hydrogen peroxide, quaternary ammonium compounds, most ethanol-based disinfectants, and antiseptics at normally used concentrations. Thorough washing of herbs and produce was effective in reducing, but not eliminating, NoV in most products. Washing hands with soap generally reduced NoV by
... In particular, UV and higher temperatures increase oxidative stress, thus inactivating enteric viral particles, including MS2 phages, in the environment [8][9][10][11][12]. The intentional addition of exogenous oxidants (e.g., hypochlorous acid, ozone) for disinfection purposes is also known to be an effective means of inactivating enteric viral particles, including MS2 phages [2,10,[13][14][15][16]. Oxidantdependent viral inactivation may also take place in the human gut. ...
... While the impact of exogenous oxidants on the infectivity of enteric viral particles, including MS2 phages, has been extensively studied [8,[11][12][13][14][15][16][24][25][26][27][28][29], little is known about the potential impact of endogenous ROS produced by host cells on the replication and infectivity of enteric viral particles. It is reasonable to suggest that endogenous oxidants can inactivate a viral particle using the same mechanism(s) as exogenous oxidants. ...
Article
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Most of the defective/non-infectious enteric phages and viruses that end up in wastewater originate in human feces. Some of the causes of this high level of inactivity at the host stage are unknown. There is a significant gap between how enteric phages are environmentally transmitted and how we might design molecular tools that would only detect infectious ones. Thus, there is a need to explain the low proportion of infectious viral particles once replicated. By analyzing lysis plaque content, we were able to confirm that, under aerobic conditions, Escherichia coli produce low numbers of infectious MS2 phages (I) than the total number of phages indicated by the genome copies (G) with an I/G ratio of around 2%. Anaerobic conditions of replication and ROS inhibition increase the I/G ratio to 8 and 25%, respectively. These data cannot only be explained by variations in the total numbers of MS2 phages produced or in the metabolism of E. coli. We therefore suggest that oxidative damage impacts the molecular replication and assembly of MS2 phages.
... This virus is reportedly more sensitive to PCA solution than to PAA solution (Wutzler and Sauerbrei 2004). These different sensitivities of MNV-1 and poliovirus were not observed in the case of hypochlorous acid, another oxidizing compound (Kitajima et al. 2010). ...
... Like chlorine dioxide, hypochlorous acid is effective at lower concentrations than peroxyacid at reducing viral population in suspension by at least 3 log 10 . Treatments with as little as a few mg L -1 for a few seconds are virucidal (Kitajima et al. 2010;Lim et al. 2010). In contrast, their effectiveness decreases substantially when the viruses are attached to hard surfaces (Kim et al. 2012;Sabbah et al. 2010), conditions under which their effectiveness is comparable to that of PAA or PPA solution. ...
Article
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This study was conducted to evaluate the efficacy of four different peroxyacids, namely peracetic (PAA), perpropionic (PPA), perlactic (PLA), and percitric (PCA) for inactivating viruses in suspension or attached to stainless steel or polyvinyl chloride surfaces. The test virus was a proxy for human norovirus, namely murine norovirus 1. Plaque-forming units in suspension (10(7) per mL) were treated with 50-1,000 mg L(-1) peroxyacid (equilibrium mixture of organic acid, hydrogen peroxide, peroxyacid, and water) for 1-10 min. Inactivation was measured by plaque assay. PAA and PPA were the most effective, with a 5 min treatment at 50 mg L(-1) being sufficient to reduce viral titer by at least 3.0 log10, whether the virus was in suspension or attached to stainless steel or polyvinyl chloride disks under clean or fouled conditions. Combinations of organic acid and hydrogen peroxide were found ineffective. Similar inactivation was observed in the case of virus in artificial biofilm (alginate gel). These short super-oxidizers could be used for safe inactivation of human noroviruses in water or on hard surfaces.
... Ozonation requires sophisticated techniques and operational methods and is a bit expensive [7]. Chlorination is most widely used inexpensive and effective chemical process for multiple applications, such as the deactivation of pathogens such as Escherichia coli, Rotavirus, Salmonella, and Shigella, adenoviruses and Pseudomonas aeruginosa species in drinking water, swimming pool water and wastewater [8]. Chlorine is a commonly used chemical for water disinfection, and the fate of chlorine in the water has been studied [9]. ...
Article
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Climatic conditions are fundamental to life on earth and their destruction or disturbance by direct or indirect human activities is the greatest threat to human health. Human life on earth is directly associated with environmental factors such as “air” and “water.” Pollution of air by toxic substances by the activities of mankind has shown to cause serious health issues, including damage to the immune, respiratory, neurological, and reproductive systems, and other health problems like cancer. Water intended for human consumption should be free from microorganisms and toxic substances. The impact and drastic effects of chlorinated water and their impact on human health are poorly studied. Chlorination is an inexpensive and effective process for disinfecting water worldwide. During the disinfection, the chlorine generates hundreds of different by-products called chlorination by-products such as trihalomethanes and halo acetic acids (HAA’s) at low levels. In this article we address the action of two HAA’s, tri- and di-chloroacetic acid and their impact on the progression of cancer, respiratory disorder, and neurological anomalies. © 2015, Asian Journal of Pharmaceutical and Clinical Research. All rights reserved.
... MNV S7-PP3 (AB435515) is a plaquepurified strain of MNV S7, which was isolated from a conventional mouse by Yukinobu Tohya, Nihon University, Japan. This strain is phylogenetically distinct from MNV1 but has been used as a surrogate for human norovirus (23). MgV vMC0 (ATCC VR-1597) is a recombinant virus derived from MgV strain M, which has been used as a process control virus in the quantification of enteric viruses in food and water (24). ...
Article
The inability of molecular detection methods to distinguish disinfected virions from infectious ones has hampered the assessment of infectivity for enteric viruses caused by disinfection practices. In the present study, the reduction of infectivity of murine norovirus S7-PP3 and mengovirus vMC0, surrogates of human noroviruses and enteroviruses, respectively, caused by free chlorine treatment was characterized culture-independently by detecting carbonyl groups on viral capsid protein. The amount of carbonyls on viral capsid protein was evaluated by the proportion of biotinylated virions trapped by avidin-immobilized gel (%adsorbed). This culture-independent approach demonstrated that the %adsorbed was significantly correlated with the logarithm of the infectious titer of tested viruses. Taken together with the results of previous reports, the result obtained in this study indicates that the amount of carbonyls on viral capsid protein of four important families of waterborne pathogenic viruses: Mastroviridae, Reoviridae, Caliciviridae, and Picornaviridae, is increased in proportion to the received oxidative stress of free chlorine. There was also a significant correlation between the %adsorbed and the logarithm of the ratio of genome copy number to PFU, which enables estimation of the infectious titer of a subject virus by measuring values of the total genome copy number and the %adsorbed. The proposed method is applicable when the validation of 4-log reduction of viruses, a requirement in USEPA guidelines for virus removal from water, is needed along with clear evidence of the oxidation of virus particles with chlorine-based disinfectants. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
... Indeed, a 1 mM concentration resulted in 1.7 log reduction in infectious phages on average after 10 min treatment (Table 1). This oxidizing agent has already been identified as being able to inactivate MS2 phage, hepatitis B virus, poliovirus or murine norovirus, and to reduce the number of human norovirus genome copies (Nuanualsuwan and Cliver 2003;Kitajima et al. 2010;Wigginton et al. 2012). These two oxidizing agents therefore impaired the infective capacity of Qβ differently under our conditions. ...
Article
Full-text available
Qβ phages infect E. coli in the human gut by recognizing F-pili as receptors. Infection therefore occurs under reducing conditions induced by physiological agents (e.g. glutathione) or the intestinal bacterial flora. After excretion in the environment, phage particles are exposed to oxidizing conditions and sometimes disinfection. If inactivation does not occur, the phage may infect new hosts in the human gut through the oral route. During such a life cycle, we demonstrated that, outside the human gut, cysteines of the major protein capsid of Qβ phage form disulfide bonds. Disinfection with NaClO does not allow over-oxidation to occur. Such oxidation induces inactivation rather by irreversible damage to the minor proteins. In the presence of glutathione, most disulfide bonds are reduced, which slightly increases the capacity of the phage to infect E. coli in vitro. Such reduction is reversible and barely alters infectivity of the phage. Reduction of all disulfide bonds by dithiothreitol leads to complete capsid destabilization. These data provide new insights into how the phages are impacted by oxidizing-reducing conditions outside their host cell and raises the possibility of the intervention of the redox during life cycle of the phage.
... Under exposure scenarios in this study, there was a 1-log 10 difference in calculated LR target values of NoV GII between the tolerable disease burden values of 10 À4 and 10 À6 DALY pppy . Kitajima et al. experimentally demonstrated that an approximate 1-log 10 difference in human norovirus reduction by chlorination led to an order increase in its CT values (expressed by disinfectant concentration and contact time) (Kitajima et al., 2010), which may have an economic impact on the operation of a wastewater reclamation process. Our suggestion is that the tolerable annual disease burden for wastewater reclamation and reuse should be subject to change based on the local context, including socio-economic background. ...
Article
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Multiple-barriers are widely employed for managing microbial risks in water reuse, in which different types of wastewater treatment units (biological treatment, disinfection, etc.) and health protection measures (use of personal protective gear, vegetable washing, etc.) are combined to achieve a performance target value of log10 reduction (LR) of viruses. The LR virus target value needs to be calculated based on the data obtained from monitoring the viruses of concern and the water reuse scheme in the context of the countries/regions where water reuse is implemented. In this study, we calculated the virus LR target values under two exposure scenarios for reclaimed wastewater irrigation in Japan, using the concentrations of indigenous viruses in untreated wastewater and a defined tolerable annual disease burden (10⁻⁴ or 10⁻⁶ disability-adjusted life years per person per year (DALYpppy)). Three genogroups of norovirus (norovirus genogroup I (NoV GI), geogroup II (NoV GII), and genogroup IV (NoV GIV)) in untreated wastewater were quantified as model viruses using reverse transcription-microfluidic quantitative PCR, and only NoV GII was present in quantifiable concentration. The probabilistic distribution of NoV GII concentration in untreated wastewater was then estimated from its concentration dataset, and used to calculate the LR target values of NoV GII for wastewater treatment. When an accidental ingestion of reclaimed wastewater by Japanese farmers was assumed, the NoV GII LR target values corresponding to the tolerable annual disease burden of 10⁻⁶ DALYpppy were 3.2, 4.4, and 5.7 at 95, 99, and 99.9%tile, respectively. These percentile values, defined as “reliability,” represent the cumulative probability of NoV GII concentration distribution in untreated wastewater below the corresponding tolerable annual disease burden after wastewater reclamation. An approximate 1-log10 difference of LR target values was observed between 10⁻⁴ and 10⁻⁶ DALYpppy. The LR target values were influenced mostly by the change in the logarithmic standard deviation (SD) values of NoV GII concentration in untreated wastewater and the reliability values, which highlights the importance of accurately determining the probabilistic distribution of reference virus concentrations in source water for water reuse.
... The integrated CT plot in Fig. 4 shows that hNoV GII exhibited comparable or greater resistance to molecular reduction by FC than other viruses in this study in all wash waters. This is consistent with other studies that have compared the resistance of hNoV GII to FC with that of cultivable surrogates (54,(60)(61)(62)(63)(64). However, Fig. 4 also demonstrates that RT-qPCR reductions for hNoV GI were greater than RT-qPCR reductions for MS2 at all shown CT values in all three wash waters. ...
Article
Human noroviruses (hNoVs) are a known public health concern associated with the consumption of leafy green vegetables. While a number of studies have investigated pathogen reduction on the surfaces of leafy greens during the postharvest washing process, there remains a paucity of data on the level of treatment needed to inactivate viruses in the wash water, which is critical for preventing cross-contamination. The objective of this study was to quantify the susceptibility of hNoV genotype I (GI), hNoV GII, murine norovirus (MNV), and bacteriophage MS2 to free chlorine in whole leaf, chopped romaine, and shredded iceberg lettuce industrial leafy green wash waters, each sampled three times over a 4-month period. A suite of kinetic inactivation models was fit to the viral reduction data to aid in quantification of concentration-time (CT) values. Results indicate that 3-log10 infectivity reduction was achieved at CT values of less than 0.2 mg · min/liter for MNV and 2.5 mg · min/liter for MS2 in all wash water types. CT values for 2-log10 molecular reduction of hNoV GI in whole leaf and chopped romaine wash waters were 1.5 and 0.9 mg · min/liter, respectively. For hNoV GII, CT values were 13.0 and 7.5 mg · min/liter, respectively. In shredded iceberg wash water, 3-log10 molecular reduction was not observed for any virus over the time course of experiments. These findings demonstrate that noroviruses may exhibit genogroup-dependent resistance to free chlorine and emphasize the importance of distinguishing between genogroups in hNoV persistence studies. IMPORTANCE Postharvest washing of millions of pounds of leafy greens is performed daily in industrial processing facilities with the intention of removing dirt, debris, and pathogenic microorganisms prior to packaging. Modest inactivation of pathogenic microorganisms (less than 2 log10) is known to occur on the surfaces of leafy greens during washing. Therefore, the primary purpose of the sanitizing agent is to maintain microbial quality of postharvest processing water in order to limit cross-contamination. This study modeled viral inactivation data and quantified the free-chlorine CT values that processing facilities must meet in order to achieve the desired level of hNoV GI and GII reduction. Disinfection experiments were conducted in industrial leafy green wash water collected from a full-scale fresh produce processing facility in the United States, and hNoV GI and GII results were compared with surrogate molecular and infectivity data.
... Concerning viruses, norovirus is considered to be of the greatest concern in regard to fresh-cut produce (66,67). Although there have been large fluctuations in inactivation of norovirus with free chlorine in various studies (dependent on the type of detection, if the viruses are aggregated or dispersed, and if free or total chlorine is measured), concentration ϫ contact times from studies with free chlorine in loworganic-loaded waters show that norovirus and its more practical surrogate murine norovirus are both highly vulnerable to chlorination (31,68,69). Protozoan parasites, such as Cryptosporidium parvum and Cyclospora cayetanensis, have also been associated with outbreaks related to fresh produce consumption, and countries in Latin America have recognized them as pathogens of concern (4,67,70,71). ...
... Both MNV S7 strains and a prototype MNV-1 strain have been used as foodborne pathogen models for human noroviruses. MNV S7 strains have been widely used by Japanese and U.S. researchers as a free chlorine inactivation model (44), in a test for a plant-based antiviral substance (45), and in an investigation of functional receptor for MNV (34). MNV S7-PP3 cells were propagated, enumerated, and purified according to the published protocols (46). ...
Article
Human noroviruses are excreted in feces from infected individuals and included in wastewater. It is critical to remove/inactivate them in wastewater treatment processes, particularly in the disinfection step, before release to aquatic environments. However, the high mutation rates of human noroviruses raise concerns about the emergence of strains that are less susceptible to disinfectants and can survive even after wastewater treatment. This study aimed to demonstrate the strain-dependent susceptibility of norovirus to free chlorine. A population originated from the murine norovirus strain S7-PP3, a surrogate for human noroviruses in environmental testing, was exposed to free chlorine and then propagated in a host cell. This cycle of free chlorine exposure followed by propagation in cells was repeated 10 times, and populations with lower susceptibility to free chlorine were obtained from two independent trials of chlorine exposure cycles. Open reading frame 2 (ORF2) and ORF3 of the murine norovirus genome were analyzed by next-generation sequencing, and a unique nonsynonymous mutation (corresponding to a change from phenylalanine to serine) at nucleotide (nt) 7280 in ORF3, which encodes the minor capsid protein VP2, was found in chlorine-exposed populations from both trials. It was confirmed that all of the clones from the chlorine-treated population had lower susceptibility to free chlorine than those from the control population. These results indicate that exposure to free chlorine and dilution exert different driving forces to form murine norovirus (MNV) quasispecies, and that there is a selective force to form MNV quasispecies under free chlorine exposure.
... Previous research comparing hNoVs with surrogate viruses by RT-qPCR also found hNoV GI and MNV to be more susceptible to PAA, while hNoV GII and MS2 were more persistent during PAA treatment (Dunkin et al. 2017a). Disinfection studies employing free chlorine have suggested that MNV and hNoV GII exhibited similar reductions in response to disinfection (Kitajima et al. 2010;Tung et al. 2013), though similarities may be attributable to the use of free chlorine in these experiments, which is a non-specific oxidant that may have quickly oxidized both hNoV GII and MNV nucleic acid. In summary, PAA caused a moderate removal of hNoV gene copies, with hNoV GI reduction similar to that of surrogate virus MNV, while hNoV GII showed behavior more similar to MS2. ...
Article
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With increasing interest in peracetic acid (PAA) as a disinfectant in water treatment processes, this study determined PAA treatment effects on human noroviruses (hNoVs) genotype I (GI) and genotype II (GII) as well as effects on bacteriophage MS2 and murine norovirus (MNV) in relation to pH. Across all pH conditions, PAA achieved between 0.2 and 2.5 log10 reduction of hNoVs over 120 min contact time in buffer solution as measured by reverse transcription-qPCR (RT-qPCR). The PAA treatments produced similar RT-qPCR reductions of MS2 and MNV, in the range of 0.2–2.7 log10. Infectivity assays achieved > 4 log10 reduction of both MS2 and MNV in buffer solution after 120 min contact time. Comparing PAA activity across varying pH, disinfection at pH 8.5, in general, resulted in less reduction of infectivity and molecular signals compared to pH conditions of 6.5 and 7.5. This difference was most pronounced for reductions in infectivity of MNV and MS2, with as much as 2.7 log10 less reduction at pH 8.5 relative to lower pH conditions. This study revealed that PAA was an effective disinfectant for treatment of hNoV GI and GII, MS2 and MNV, with greatest virus reduction observed for MS2 and MNV infectivity. RT-qPCR reductions of MS2 and MNV were lower than concurrent MS2 and MNV infectivity reductions, suggesting that observed hNoV RT-qPCR reductions may underestimate reductions in hNoV infectivity achieved by PAA. Although virus disinfection by PAA occurred at all evaluated pH levels, PAA is most effective at pH 6.5–7.5.
... MNV has been described as the most prevalent viral agent in mice colonies [10,11,17,20,21,25,40], and NoV infection of laboratory animals has been diagnosed using rt-PCr [11,28], qrt-PCr [9], enzyme-linked immunosorbent assay (elisa) [17,18] and multiplexed fluorescent immunoassay [11]. Currently, nested and semi-nested PCr is the most sensitive diagnostic assay for the detection of low concentrations of rNa virus, and is mainly used for stool and environmental samples [19]. in this study, we have developed a semi-nested rt-PCr protocol for the detection of NoV in fecal samples from laboratory rats. ...
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Norovirus is a highly prevalent pathogen that can infect a wide range of host species. Thus far, there have only been two reports of norovirus infection in rats. Diagnostic assays for the detection of norovirus are well established, but a specific molecular assay for the diagnosis of norovirus infection in laboratory rats has not yet been reported. In this study, we describe the development of a sensitive, semi-nested RT-PCR assay for detection of norovirus in fecal samples from Rattus norvegicus, reared in animal facilities under different sanitary barrier conditions. Additionally, we describe the first report of the presence of norovirus in rat colonies from Brazilian animal facilities.
... In addition to MNV and MS2, poliovirus has been used as a cultivable non-enveloped enteric virus used in the study of inactivation. In a study investigating the ability of chlorine to inactivate non-enveloped viruses in water, Kitajima et al. (2010) inoculated water with poliovirus and MNV prior to chlorination and studied the resulting viral reduction using plaque assay. Two free chlorine concentrations of 0.5 mg l −1 and 0.1 mg l −1 were used. ...
Article
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Human noroviruses are the leading cause of foodborne illness globally. Numerous challenges in control of these viruses exist due to multiple viral characteristics: the ability to environmentally persist for over a month; relatively low infectious dose; lack of extremely effective, non-corrosive inactivation agents; and considerable inhibitory effects of food matrices and organic loads observed with common use of promising inactivation agents. Although a major breakthrough in the field, recent in vitro human norovirus cultivation systems have been limited in their ability to be widely utilized for identification of promising inactivation agents. Thus, cultivable human norovirus surrogates remain the most readily utilizable models for studying the effect of various inactivation agents on viral infectivity. The purpose of this review is to highlight recent developments and reports related to norovirus surrogate inactivation with a special focus on the various degrees of food matrix-associated inhibition for different inactivation agents.
... Similarly, the incidence of NoVs in water and shellfish samples was the highest in the low-temperature period. Prior studies conducted in Japan, South Korea, and Spain have reported that the incidence of NoVs was the highest in the winter season than in spring [41][42][43]. Moreover, most of the NoVs outbreaks are reported in the winter season worldwide due to their better survival/spread in low-temperature [44,45]. ...
Article
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The enteric viruses, including adenovirus (AdVs) and norovirus (NoVs), in shellfish is a significant food safety risk. This study investigated the prevalence, seasonal occurrence, genetic diversity, and quantification of AdVs and NoVs in the water and cultured shellfish samples at the four major coastal oyster breeding farms (COBF), five major fishing ports (FP), and their markets in Taiwan. The AdVs/NoVs in the water and shellfish samples were isolated by the membrane filtration and direct elution methods. The RNA of NoVs was reverse-transcribed into complementary DNA through reverse transcription reaction. Further NoVs and AdVs were detected using nested PCR. A higher detection rate was recorded in the low-temperature period than high-temperature. Detection difference was noted between nested PCR and qPCR outcomes for AdVs. The total detection rate of AdVs was higher in the water samples (COBF-40.6%, FP 20%) than the shellfish samples (COBF-11.7% and FP 6.3%). The AdVs load in the water and shellfish samples ranged from 1.23 × 103 to 1.00 × 106 copies/L and 3.57 × 103 to 4.27 × 104 copies/100g, respectively. The total detection of NoVs was highest in the water samples of the FP and their market shellfish samples (11.1% and 3.2%, respectively). Genotyping and phylogenetic analysis were identified as the prevalent AdVs and NoVs genotypes in the water and shellfish samples: A species HAdVs serotype 12; F species HAdVs serotype 41; and C species PAdVs serotype 5 (NoVs GI.2, GI.3 and GII.2). No significant differences were observed between the presence of AdVs, and all of the water quality parameters evaluated (heterotrophic plate count, water temperature, turbidity, pH, salinity, and dissolved oxygen). The virus contamination occurs mainly due to the direct discharge of domestic sewage, livestock farm, and fishing market wastewater into the coastal environment. Thus, this study suggested framing better estuarine management to prevent AdVs/NoVs transmission in water and cultured/distributed shellfish.
... In fact, some studies had performed viral disinfection studies employing PCR, and some studies indeed showed a reduction of the viral copies. Nevertheless, they observed the same profile: the genome integrity decreased more slowly than the viral viability [18,19,30,[50][51][52][53][54]. Although some studies have reported that free chlorine can damage the viral genetic material [30] by interacting with the amine group of nucleotides [29], it is suggested that the extent of DNA damage caused by free chlorine is not sufficient to detect viral inactivation by the qPCR technique, which often results in very small amplicons [55]. ...
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Background In Brazil, ordinance no. 2,914/2011 of the Ministry of Health requires the absence of total coliforms and Escherichia coli (E. coli) in treated water. However it is essential that water treatment is effective against all pathogens. Disinfection in Water Treatment Plants (WTP) is commonly performed with chlorine. Methods The recombinant adenovirus (rAdV), which expresses green fluorescent protein (GFP) when cultivated in HEK 293A cells, was chosen as a model to evaluate the efficiency of chlorine for human adenovirus (HAdV) inactivation in filtered water samples from two WTPs: Lagoa do Peri (pH 6.9) and Morro dos Quadros (pH 6.5). Buffered demand free (BDF) water (pH 6.9 and 8.0) was used as control. The samples were previously submitted to physicochemical characterization, and bacteriological analysis. Two free chlorine concentrations and two temperatures were assayed for all samples (0.2 mg/L, 0.5 mg/L, and 15°C, and 20°C). Fluorescence microscopy (FM) was used to check viral infectivity in vitro and qPCR as a molecular method to determine viral genome copies. Real treated water samples from the WTP (at the output of WTP and the distribution network) were also evaluated for total coliforms, E. coli and HAdV. Results The time required to inactivate 4log10 of rAdV was less than 1 min, when analyzed by FM, except for BDF pH 8.0 (up to 2.5 min for 4log10). The pH had a significant influence on the efficiency of disinfection. The qPCR assay was not able to provide information regarding rAdV inactivation. The data were modeled (Chick-Watson), and the observed Ct values were comparable with the values reported in the literature and smaller than the values recommended by the EPA. In the treated water samples, HAdV was detected in the distribution network of the WTP Morro dos Quadros (2.75 × 103 PFU/L). Conclusion The Chick-Watson model proved to have adjusted well to the experimental conditions used, and it was possible to prove that the adenoviruses were rapidly inactivated in the surface water treated with chlorine and that the recombinant adenovirus expressing GFP is a good model for this evaluation.
... In this study, we used two methods to assess the efficacy: i.e., the infectivity assay and RT-qPCR. These two assays generally have different interpretation of the results (Kitajima et al. 2010;. RT-qPCR detects the intact genomic RNA of the virus including the damaged capsids, whereas the infectivity assay does not detect the virus which have damaged capsids. ...
Article
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Human norovirus is one of the major causes of food-borne gastroenteritis, and it can be easily transmitted from infected person, virus-contaminated foods, and environmental surfaces. Effective disinfection method is needed to stop the transmission of human norovirus. CAC-717 is a new disinfectant consisting of calcium hydrogen carbonate mesoscopic crystals. We aimed to evaluate the efficacy of CAC-717 against human norovirus. This study used human norovirus derived from fecal specimens and cultured murine norovirus, which is one of the surrogate viruses for human norovirus. The disinfection effect against murine norovirus was estimated by infectivity assay and transmission electron microscopy. The inactivation effect against human norovirus was assessed by reverse transcription polymerase chain reaction. Disinfection effect of CAC-717 against the infectivity of murine norovirus, was shown within 100 seconds after the CAC-717 treatment, presenting the destruction of viral capsids. The treatment of CAC-717 significantly reduced human norovirus genomic RNA (3.25-log reduction) by the presence of the mesoscopic structure of calcium hydrogen carbonate. CAC-717 stably inactivated human norovirus in stool suspensions. The inactivation effect of CAC-717 against human norovirus was less susceptible to organic substances than sodium hypochlorite. CAC-717 would be a useful alternative for disinfecting human norovirus in contaminated environmental surfaces.
... In this study, it was obtained from Dr. Tohya, Nihon University, Japan. This strain has been widely used in investigating the receptor for MNV [35] and tests for virucidal and antiviral substances [16,36]. The MNV S7-PP3 strain was propagated in RAW 264.7 cells (ATCC TIB-71). ...
Article
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Human noroviruses are the most common pathogens causing acute gastroenteritis and may lead to more severe illnesses among immunosuppressed people, including elderly and organ transplant recipients. To date, there are no safe and effective vaccines or antiviral agents for norovirus infections. In the present study, we aimed to demonstrate the antiviral activity of monogalactosyl diacylglyceride (MGDG) isolated from a microalga, Coccomyxa sp. KJ, against murine norovirus (MNV) and feline calicivirus (FCV), the surrogates for human norovirus. MGDG showed virucidal activities against these viruses in a dose- and time-dependent manner—MGDG at 100 μg/mL reduced the infectivity of MNV and FCV to approximately 10% after 60 min incubation. In the animal experiments of MNV infection, intraoral administration of MGDG (1 mg/day) exerted a therapeutic effect by suppressing viral shedding in the feces and produced high neutralizing antibody titers in sera and feces. When MGDG was orally administered to immunocompromised mice treated with 5-fluorouracil, the compound exhibited earlier stopping of viral shedding and higher neutralizing antibody titers of sera than those in the control mice administered with distilled water. Thus, MGDG may offer a new therapeutic and prophylactic alternative against norovirus infections.
... Similar to other enteric viruses, they may also be indirectly transmitted through the consumption of contaminated food and water [8,9]. The virus may survive long periods in surfaces and extreme temperatures (freezing temperatures and up to 60 • C), with low resistance to chlorine disinfection [10][11][12][13]. Due to its high stability and extreme infectivity to humans, indirect transmission from contaminated drinking water have been documented in previous studies [14][15][16][17][18]. ...
Article
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On 2 February 2017, Epidemiological Surveillance Services were notified of an outbreak of acute gastroenteritis (AGE) among schoolchildren who had taken part of a school trip from 30 January to 3 February 2017 at a holiday camp in Catalonia. A retrospective cohort study was performed to identify the causative agent, estimate the magnitude of the outbreak and identify its source, as well as to determine the route of transmission. Data collected by standardised questionnaires identified 41 episodes of AGE among 174 individuals who attended the camp. Cases had mainly symptoms of abdominal pain (73.8%), nausea (64.3%), vomiting (54.8%), diarrhoea (45.2%) and headache (42.9%). Consumption of water was associated with gastroenteritis (crude RR: 1.72, 95%CI: 1.01–2.92; adjusted RR: 1.88, 95%CI 1.03–3.56). NoV GII was detected in faeces (5 out of 13) and water samples. Additionally, faecal indicator bacteria and protozoa were detected in water samples.The outbreak showed a high attack rate and was caused by a natural water fountain not properly treated and not monitored for safety quality. There could have been a discharge of wastewater at a point close to the fountain; however, the source of contamination of the water could not be identified.Health education may be useful to eliminate risks associated with the consumption of untreated water from natural fountains.
... 31,32 Recent studies with murine and human norovirus strains reported higher resistance to chlorine disinfection (in aquatic studies) compared with poliovirus. 33 The innate resistance of a virus, as with other micro-organisms, can be disinfectant-specific. This has been shown, for example, in UV water disinfection studies with adenoviruses. ...
Article
The Spaulding classification, originally proposed in 1957, is a widely used system for matching the disinfection and sterilization of surfaces, particularly those of re-usable medical/surgical devices, with available processes. It presents a ranking, from simple disinfection through to sterilization, that should be considered in the reprocessing of devices, based on the risks associated with their use, ranging from 'critical' (presenting a high risk), through 'semi-critical' to 'non-critical' (presenting a low risk). The different levels of disinfection are based on demonstrating antimicrobial activity against established marker micro-organisms representing a range of pathogens. Although this classification system is probably as valid today as it was in 1957, the understanding of microbiology and micro-organisms has changed. This article discusses some examples of disinfection studies with viruses, bacteria, protozoa and prions that challenge the current definitions and expectations of high-, intermediate- and low-level disinfection. In many of these examples, the test micro-organisms demonstrate atypical tolerance or resistance profiles to disinfection processes. In addition to laboratory-based studies, there is now clinical evidence for at least some of these micro-organisms that biocide resistance can lead to infection outbreaks due to unexpected disinfection failure. These reports should encourage the reader to challenge current dogma, and reconsider the expectations of disinfection and sterilization practices.
... Then, the flask was frozen and thawed once to recover the MHV. The recovered MHV was purified by membrane filtration with a cellulose acetate filter (0.2 μm, DISMIC-25CS, Advantec, Tokyo, Japan) and gel filtration with an Illustra Microspin S-300 HR column (GE Healthcare, Tokyo, Japan) (Kitajima et al., 2010;Sangsanont et al., 2014). The purified MHV was regarded as intact MHV stock. ...
Article
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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes have been detected in wastewater worldwide. However, the assessment of SARS-CoV-2 infectivity in wastewater has been limited due to the stringent requirements of biosafety level 3. The main objective of this study is to investigate the applicability of capsid integrity RT-qPCR for the selective detection of intact SARS-CoV-2 in wastewater. Three capsid integrity reagents, namely ethidium monoazide (EMA, 0.1–100 μM), propidium monoazide (PMA, 0.1–100 μM), and cis-dichlorodiammineplatinum (CDDP, 0.1–1000 μM), were tested for their effects on different forms (including free genomes, intact and heat-inactivated) of murine hepatitis virus (MHV), which was used as a surrogate for SARS-CoV-2. CDDP at a concentration of 100 μM was identified as the most efficient reagent for the selective detection of infectious MHV by RT-qPCR (CDDP-RT-qPCR). Next, two common virus concentration methods including ultrafiltration (UF) and polyethylene glycol (PEG) precipitation were investigated for their compatibility with capsid integrity RT-qPCR. The UF method was more suitable than the PEG method since it recovered intact MHV (mean ± SD, 38% ± 29%) in wastewater much better than the PEG method did (0.013% ± 0.015%). Finally, CDDP-RT-qPCR was compared with RT-qPCR alone for the detection of SARS-CoV-2 in 16 raw wastewater samples collected in the Greater Tokyo Area. Five samples were positive for SARS-CoV-2 when evaluated by RT-qPCR alone. However, intact SARS-CoV-2 was detected in only three positive samples when determined by CDDP-RT-qPCR. Although CDDP-RT-qPCR was unable to determine the infectivity of SARS-CoV-2 in wastewater, this method could improve the interpretation of positive results of SARS-CoV-2 obtained by RT-qPCR.
... −1 led to a 1.0-2.0 log 10 reduction in the genomes of purified HuNoVs (Shin and Sobsey, 2008;Kitajima et al., 2010;Sano et al., 2010). Conversely, a 0.4 log 10 reduction in genomes was observed in non-purified HuNoVs, using CT values of 2,500 mg.min.l ...
Article
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Human noroviruses (HuNoVs) are one of the leading causes of acute gastroenteritis worldwide. HuNoVs are frequently detected in water and foodstuffs. Free chlorine and peroxynitrite (ONOO−) are two oxidants commonly encountered by HuNoVs in humans or in the environment during their natural life cycle. In this study, we defined the effects of these two oxidants on GII.4 HuNoVs and GII.4 virus-like particles (VLPs). The impact on the capsid structure, the major capsid protein VP1 and the ability of the viral capsid to bind to histo-blood group antigens (HBGAs) following oxidative treatments were analyzed. HBGAs are attachment factors that promote HuNoV infection in human hosts. Overall, our results indicate that free chlorine acts on regions involved in the stabilization of VP1 dimers in VLPs and affects their ability to bind to HBGAs. These effects were confirmed in purified HuNoVs. Some VP1 cross-links also take place after free chlorine treatment, albeit to a lesser extent. Not only ONOO− mainly produced VP1 cross-links but can also dissociate VLPs depending on the concentration applied. Nevertheless, ONOO− has less effect on HuNoV particles.
... The water disinfection process inactivates or kills pathogens prior to human consumption. The most global conventional disinfection processes are categorized into chemical and physical methods, including chlorination [2], ozonation [3] and UV irradiation [4]. On the other hand, previous studies have proven that the formation of disinfection by-products (DBP) are carcinogenic and cannot be avoided globally when chlorine is added to water. ...
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The target of this work is to investigate and assess the utilization of the synthesized in-situ deposition of metal oxide nanoparticles such as nano-nickel oxide (nNiO), nanocopper oxides (nCuO) and nanoiron oxides (nFe3O4) in aminated cellulose (Acell), as a protected and compelling antibacterial channel of contamination from domestic wastewater. The prepared Acell and nNiO/Acell, nCuO/Acell and nFe3O4/Acell nanocomposites were characterized by field emission-scanning electron microscopy (FE-SEM), Fourier transform-infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), selected area diffraction pattern (SAED) and X-ray diffraction techniques (XRD). TEM declared the synthesis of nNiO, nCuO and nFe3O4 with regular size of 10, 23 and 43 nm, correspondingly. The antibacterial impact of both nNiO/Acell, nCuO/Acell and nFe3O4/Acell nanocomposites was inspected against Gram-positive microorganisms (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative microbes (Escherichia coli, Salmonella typhi) utilizing agar disk diffusion routes. Furthermore, the ability of the synthesized nanocomposites as sterilizers for optional domestic wastewater was studied. The data for the disk diffusion obtained revealed that nFe3O4/Acell had a greater antibacterial impact than nCuO/Acell and nNiO/Acell. In addition, the purification of domestic wastewater utilizing 1.0 mg of nFe3O4, nCuO and nNiO in 1 gm of Acell was accomplished by killing 99.6%, 94.5% and 92.0% of total and fecal coliforms inside 10 mins, respectively.
... For example, a 3.6 log 10 reduction in genomes of "purified HuNoVs" was obtained for a Ct value of 15 mg.min.L À 1 , while a 0.4 log 10 reduction in genomes of "untreated HuNoVs" was reached for a Ct value of 250 mg. min.L À 1 (Kitajima et al., 2010;Tung et al., 2013). The matrix effect promotes the persistence of HuNoVs during chlorine disinfection. ...
Article
Human noroviruses (HuNoVs) are a main cause of acute gastroenteritis worldwide. They are frequently involved in foodborne and waterborne outbreaks. Environmental transmission of the virus depends on two main factors: the ability of viral particles to remain infectious and their adhesion capacity onto different surfaces. Until recently, adhesion of viral particles to food matrices was mainly investigated by considering non-specific interactions (e.g. electrostatic, hydrophobic) and there was only limited information about infectious HuNoVs because of the absence of a reliable in vitro HuNoV cultivation system. Many HuNoV strains have now been described as having specific binding interactions with human Histo-Blood Group Antigens (HBGAs) and non-HBGA ligands found in food and the environment. Relevant approaches to the in vitro replication of HuNoVs were also proposed recently. On the basis of the available literature data, this review discusses the opportunities to use this new knowledge to obtain a better understanding of HuNoV transmission to human populations and better evaluate the hazard posed by HuNoVs in foodstuffs and the environment.
... 9 However, further studies into the efficacy of various sterilization chemicals and procedures have unveiled a number of pathogens resistant to typical high-level disinfection techniques. Several strains of nonenveloped norovirus, a leading cause of viral gastroenteritis, have been reported to have higher resistance to commonly used chlorine disinfectants, 10 whereas some enveloped viruses, such as HIV, HBV, and influenza virus, are vulnerable to commercial disinfectants because of an easily compromised outer envelope. Therefore, in a 2019 Expert Guidance statement 11 from the Society for Healthcare Epidemiology of America (SHEA), subsequently adopted by the American Society of Anesthesiologists, both traditional and video laryngoscope reusable handles and blades should undergo high-level disinfection (at a minimum) or sterilization prior to use. ...
Article
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Relegated to clinical afterthought, the topic of infection control has never taken center stage in our modern dental sedation and anesthesiology practices. Surgical and procedural masks, gloves, gowns, protective eyewear, and appropriate surgical attire have remained de rigueur in both fashion and custom for decades. However, the emergence of certain seminal events throughout health care history has driven mandated changes when practitioners, staff, patients, and the surrounding communities were exposed or put at risk of exposure to infectious disease. Hepatitis, human immunodeficiency virus, and now the global COVID-19 pandemic involving the novel coronavirus SARS-CoV-2, have forced us into rethinking our current practices. This review article will contextualize previous epidemics and their influence on infection control in dental settings, and it will explore the rapid evolution of current modifications to personal protective equipment and infection mitigation practices specific to sedation and anesthesia in dentistry.
... Concerning viruses, norovirus is considered to be of the greatest concern in regard to fresh-cut produce (66,67). Although there have been large fluctuations in inactivation of norovirus with free chlorine in various studies (dependent on the type of detection, if the viruses are aggregated or dispersed, and if free or total chlorine is measured), concentration ϫ contact times from studies with free chlorine in loworganic-loaded waters show that norovirus and its more practical surrogate murine norovirus are both highly vulnerable to chlorination (31,68,69). Protozoan parasites, such as Cryptosporidium parvum and Cyclospora cayetanensis, have also been associated with outbreaks related to fresh produce consumption, and countries in Latin America have recognized them as pathogens of concern (4,67,70,71). ...
Article
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Chlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated with Escherichia coli O157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The model that incorporated chlorine dose and chemical oxygen demand (COD) of the wash water accurately predicted inactivation. Listeria monocytogenes was more resistant to chlorine reconditioning in artificial wash water than Salmonella spp. and Escherichia coli O157. During the washing process with inoculated lettuce (4 log CFU/g), in the absence of chlorine, there was a rapid microbial buildup in the water that accumulated to 5.4 ± 0.4 log CFU/100 ml after 1 h. When maintaining a residual concentration of 1 mg/liter free chlorine, wash water contamination was maintained below 2.7, 2.5, and 2.5 log CFU/100 ml for tap water and artificial process water with COD values of 500 and 1,000 mg O2/liter, respectively. A model was developed to predict water contamination during the dynamic washing process. Only minor amounts of total trihalomethanes were formed in the water during reconditioning. Total trihalomethanes accumulated to larger amounts in the water during the wash water disinfection experiments and reached 124.5 ± 13.4 μg/liter after 1 h of execution of the washing process in water with a COD of 1,000 mg O2/liter. However, no total trihalomethanes were found on the fresh-cut lettuce after rinsing.
... Ozonation requires sophisticated techniques and operational methods and is a bit expensive [7]. Chlorination is most widely used inexpensive and effective chemical process for multiple applications, such as the deactivation of pathogens such as Escherichia coli, Rotavirus, Salmonella, and Shigella, adenoviruses and Pseudomonas aeruginosa species in drinking water, swimming pool water and wastewater [8]. Chlorine is a commonly used chemical for water disinfection, and the fate of chlorine in the water has been studied [9]. ...
... In the same manner as WAIC and RMSE, the predicted EFH parameters for coxsackievirus and echovirus seemed to be the same between GLM and HBM. The number of training datasets for norovirus, rotavirus, poliovirus, hepatitis A virus, adenovirus, coxsackievirus, and echovirus was 12,25,35,9,16,29, and 12, respectively . The test datasets were selected to make the number of datasets of each article as uniform as possible. ...
Article
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Hazard analysis and critical control point (HACCP) are a series of actions to be taken to ensure product consumption safety. In food poisoning risk management, researchers in the field of predictive microbiology calculate the values that provide minimum stress (e.g., temperature and contact time in heating) for sufficient microbe inactivation based on mathematical models. HACCP has also been employed for health risk management in sanitation safety planning (SSP), but the application of predictive microbiology to water-related pathogens is difficult because the variety of pathogen types and the complex composition of the wastewater matrix does not allow us to make a simple mathematical model to predict inactivation efficiency. In this study, we performed a systematic review and meta-analysis to construct predictive inactivation curves using free chlorine for enteric viruses based on a hierarchical Bayesian model using parameters such as water quality. Our model considered uncertainty among virus disinfection tests and difference in genotype-dependent sensitivity of a virus to disinfectant. The proposed model makes it possible to identify critical disinfection stress capable of reducing virus concentration that is below the tolerable concentration to ensure human health.
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The occurrence of human norovirus (NoV) genogroup I (GI) and genogroup II (GII) strains were investigated in Korea. Between 2007 and 2010, 265 samples were collected from 89 Korean water source locations. NoV GI was detected in 4.5% and NoV GII in 1.5%. Samples collected in winter had the highest occurrence; 9.4% for NoV GI and 6.3% for NoV GII. NoV GI detection was highest in groundwater, next highest in river water, and lowest in lake water (5.9%, 5.4%, and 1.6%, respectively), and NoV GII was found only in river water. When three representative Korean basin systems (Han (H)-, Geum/Seom (G/S)-, and Nakdong (N)-river basins) were compared, both NoV genogroups were high in the G/S-, but absent in the H- river basin. The most prevalent genotypes within the GI and GII groups were GI.5 and GII.4, respectively. The NoVs found in surface water were identical to those found in patients and those found in groundwater. The NoVs appeared to be transmitted from the patient to the surface water, and then to the groundwater, suggesting a fecal-oral route of transmission. This is the first nationwide surveillance of NoV in major Korean water sources.
Article
In February 2009, a group of Guatemalan school children developed acute gastroenteritis (AGE) after participating in a school excursion. We conducted a retrospective cohort investigation to characterize the outbreak and guide control measures. A case was defined as an illness with onset of diarrhea or vomiting during February 25-March 5, 2009. Participants were interviewed using a standardized questionnaire, and stool specimens were collected. We inspected the excursion site and tested water samples for total coliforms and Escherichia coli. We identified 119 excursion participants, of which 92 (77%) had been ill. Fifty-six (62%) patients sought care for their illness, and three (3%) were hospitalized. Eighteen (90%) of the 20 specimens from ill children tested positive for norovirus. Among these, 16 (89%) were of the genogroup I (GI.7) and two (11%) were genogroup II (GII.12 and GII.17). One (8%) of the 12 food handlers had norovirus (GI.7). Drinking water samples had 146 most probable numbers (MPN)/100ml of total coliforms and five MPN/100ml of E. coli. We describe the first laboratory-confirmed norovirus outbreak in Guatemala. The high illness attack rate, detection of multiple norovirus strains in sick persons, and presence of fecal contamination of drinking water indicate likely waterborne transmission.
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The Caliciviridae family of viruses contains clinically important human and animal pathogens, as well as vesivirus 2117, a known contaminant of biopharmaceutical manufacturing processes employing Chinese hamster cells. An extensive literature exists for inactivation of various animal caliciviruses, especially feline calicivirus and murine norovirus. The caliciviruses are susceptible to wet heat inactivation at temperatures in excess of 60 °C with contact times of 30 min or greater, to UV-C inactivation at fluence ≥30 mJ/cm2, to high pressure processing >200 MPa for >5 min at 4 °C, and to certain photodynamic inactivation approaches. The enteric caliciviruses (e.g.; noroviruses) display resistance to inactivation by low pH, while the non-enteric species (e.g.; feline calicivirus) are much more susceptible. The caliciviruses are inactivated by a variety of chemicals, including alcohols, oxidizing agents, aldehydes, and β-propiolactone. As with inactivation of viruses in general, inactivation of caliciviruses by the various approaches may be matrix-, temperature-, and/or contact time-dependent. The susceptibilities of the caliciviruses to the various physical and chemical inactivation approaches are generally similar to those displayed by other small, non-enveloped viruses, with the exception that the parvoviruses and circoviruses may require higher temperatures for inactivation, while these families appear to be more susceptible to UV-C inactivation than are the caliciviruses.
Article
Human noroviruses (HuNoVs) are a major cause of food borne gastroenteritis worldwide. They are often transmitted via infected and shedding food handlers manipulating foods such as deli sandwiches. The presented study aimed to simulate HuNoV transmission during the preparation of deli sandwiches in a sandwich bar. A quantitative exposure model was developed by combining the GoldSim® and @Risk® software packages. Input data were collected from scientific literature and from a two week observational study performed at two sandwich bars. The model included three food handlers working during a three hour shift on a shared working surface where deli sandwiches are prepared. The model consisted of three components. The first component simulated the preparation of the deli sandwiches and contained the HuNoV reservoirs, locations within the model allowing the accumulation of NoV and the working of intervention measures. The second component covered the contamination sources being (1) the initial HuNoV contaminated lettuce used on the sandwiches and (2) HuNoV originating from a shedding food handler. The third component included four possible intervention measures to reduce HuNoV transmission: hand and surface disinfection during preparation of the sandwiches, hand gloving and hand washing after a restroom visit. A single HuNoV shedding food handler could cause mean levels of 43 ± 18, 81 ± 37 and 18 ± 7 HuNoV particles present on the deli sandwiches, hands and working surfaces, respectively. Introduction of contaminated lettuce as the only source of HuNoV resulted in the presence of 6.4 ± 0.8 and 4.3 ± 0.4 HuNoV on the food and hand reservoirs. The inclusion of hand and surface disinfection and hand gloving as a single intervention measure was not effective in the model as only marginal reductions of HuNoV levels were noticeable in the different reservoirs. High compliance of hand washing after a restroom visit did reduce HuNoV presence substantially on all reservoirs. The model showed that good handling practices such as washing hands after a restroom visit, hand gloving, hand disinfection and surface disinfection in deli sandwich bars were an effective way to prevent HuNoV contamination of the prepared foods, but it also demonstrated that further research is needed to ensure a better assessment of the risk of HuNoV transmission during preparation of foods.
Article
Despite the health risks posed by waterborne human rotavirus (HRV), little information is available concerning the effectiveness of chlorine or chlorine dioxide (ClO2), two common disinfectants of public water sources, against HRV and their effects on its genome remain poorly understood. This study investigated the effects of chlorine and ClO2 on purified HRV by using cell culture and RT-PCR to assess virus infectivity and genetic integrity, respectively. The disinfection efficacy of ClO2 was found to be higher than that of chlorine. According to the efficiency factor Hom model, Ct value (mg/L min) ranges required for a 4-log reduction of HRV at 20 °C by chlorine and ClO2 were 5.55-5.59 and 1.21-2.47 mg/L min, respectively. Detection of the 11 HRV genome segments revealed that damage to the 1227-2354 bp of the VP4 gene was associated with the disappearance of viral infectivity by chlorine. However, no complete accordance between culturing and RT-PCR assays was observed after treatment of HRV with ClO2. These results collectively indicate that the current practice of chlorine disinfection may be inadequate to manage the risk of waterborne HRV infection, and offer the potential to monitor the infectivity of HRV adapting PCR-based protocols in chlorine disinfection.
Article
The objective of this study was to characterize human norovirus (hNoV) GI and GII reductions during disinfection by peracetic acid (PAA) and monochloramine in secondary wastewater (WW) and phosphate buffer (PB) as assessed by reverse transcription-qPCR (RT-qPCR). Infectivity and RT-qPCR reductions are also presented for surrogate viruses murine norovirus (MNV) and bacteriophage MS2 under identical experimental conditions to aid in interpretation of hNoV molecular data. In WW, RT-qPCR reductions were less than 0.5 log10 for all viruses at concentration-time (CT) values up to 450 mg-min/L except for hNoV GI, where 1 log10 reduction was observed at CT values of less than 50 mg-min/L for monochloramine and 200 mg-min/L for PAA. In PB, hNoV GI and MNV exhibited comparable resistance to PAA and monochloramine with CT values for 2 log10 RT-qPCR reduction between 300 to 360 mg-min/L. Less than 1 log10 reduction was observed for MS2 and hNoV GII in PB at CT values for both disinfectants up to 450 mg-min/L. Our results indicate that hNoVs exhibit genogroup dependent resistance and that disinfection practices targeting hNoV GII will result in equivalent or greater reductions for hNoV GI. These data provide valuable comparisons between hNoV and surrogate molecular signals that can begin the process of informing regulators and engineers on WW treatment plant design and operational practices necessary to inactivate hNoVs.
Article
Presently there is no established cell line or small animal model that allows for the detection of infectious human norovirus. Current methods based on RT-PCR and RT-qPCR detect both infectious and non-infectious virus and thus the conclusions that may be drawn regarding the public health significance of positive findings are limited. In this study, PMA RT-PCR and RT-qPCR assays were evaluated for selective detection of infectious poliovirus, murine norovirus (MNV-1), and Norwalk virus. Viruses were inactivated using heat, chlorine, and ultraviolet light (UV). Infectious and non-infectious viruses were treated with PMA before RT-PCR and RT-qPCR. PMA RT-PCR was able to differentiate selectively between infectious and heat and chlorine inactivated poliovirus. PMA RT-PCR was able to differentiate selectively between infectious and noninfectious murine norovirus only when inactivated by chlorine. However, PMA RT-PCR could not differentiate infectious Norwalk virus from virus particles rendered non-infectious by any treatment. PMA RT-PCR assay was not able to differentiate between infectious and UV inactivated viruses suggesting that viral capsid damage may be necessary for PMA to enter and bind to the viral genome. PMA RT-PCR on naked MNV-1 and Norwalk virus RNA suggest that PMA RT-PCR can be used to detect intact, potentially infectious MNV-1 and Norwalk viruses and can be used to exclude the detection of free viral RNA by PCR assay. Copyright © 2015. Published by Elsevier B.V.
Article
Fruits and vegetables are major vehicles for transmission of food-borne enteric viruses since they are easily contaminated at pre-and postharvest stages and they undergo little or no processing. However, commonly used sanitizers are relatively ineffective for removing human norovirus surrogates from fresh produce. In this study, we systematically evaluated the effectiveness of surfactants on removal of a human norovirus surrogate, murine norovirus 1 (MNV-1), from fresh produce. We showed that a panel of surfactants, including sodium dodecyl sulfate (SDS), Nonidet P-40 (NP-40), Triton X-100, and polysorbates, significantly enhanced the removal of viruses from fresh fruits and vegetables. While tap water alone and chlorine solution (200 ppm) gave only <1.2-log reductions in virus titer in all fresh produce, a solution containing 50 ppm of surfactant was able to achieve a 3-log reduction in virus titer in strawberries and an approximately 2-log reduction in virus titer in lettuce, cabbage, and raspberries. Moreover, a reduction of approximately 3 logs was observed in all the tested fresh produce after sanitization with a solution containing a combination of 50 ppm of each surfactant and 200 ppm of chlorine. Taken together, our results demonstrate that the combination of a surfactant with a commonly used sanitizer enhanced the efficiency in removing viruses from fresh produce by approximately 100 times. Since SDS is an FDA-approved food additive and polysorbates are recognized by the FDA as GRAS (generally recognized as safe) products, implementation of this novel sanitization strategy would be a feasible approach for efficient reduction of the virus load in fresh produce.
Article
Noroviruses are the commonest cause of infectious intestinal disease, and are frequently associated with outbreaks of gastroenteritis, mainly in healthcare-associated settings, but also in outbreaks associated with contaminated food and/or water. The contamination of foods can occur during production, preparation, and/or service, or, more rarely by contamination of water supply. Contamination of water supply with norovirus is rare, and usually occurs as a consequence of leakage of sewage or as a result of leaching after heavy rainfall. Outbreaks of norovirus gastroenteritis associated with contaminated food and water can have high impact as a large number of individuals can become affected quickly over a large geographical area, with a high number of secondary cases. However, adequate capture of both epidemiological and laboratory data of norovirus outbreaks remains a major challenge, as many outbreaks fail to be identified and/ or followed up and so the incidence of norovirus-associated foodborne outbreaks is not well defined. Measures for preventing norovirus contamination are centred on good hand hygiene and environmental cleaning practices in healthcare settings, food establishments and on board cruise ships. Several guidelines for responding to outbreaks in food preparation premises are available, and there is a wide range of generic legislation for food processing and handling. There is currently no licenced vaccine or antiviral drug for prophylaxis or treatment of norovirus. However, the first trial demonstrating homologous protection against illness and infection using a norovirus VLP (virus-like particle) was reported recently. Whilst promising, the vaccine is monovalent and the evidence suggests that there is little cross-protection between norovirus strains, a multivalent vaccine is likely to be the only viable option for future vaccine development.
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There is an urgent need for structurally novel anti-norovirus agents. In this study, we describe the synthesis, anti-norovirus activity, and structure–activity relationship (SAR) of a series of heterocyclic carboxamide derivatives. Heterocyclic carboxamide 1 (50% effective concentration (EC50)=37 µM) was identified by our screening campaign using the cytopathic effect reduction assay. Initial SAR studies suggested the importance of halogen substituents on the heterocyclic scaffold and identified 3,5-di-boromo-thiophene derivative 2j (EC50=24 µM) and 4,6-di-fluoro-benzothiazole derivative 3j (EC50=5.6 µM) as more potent inhibitors than 1. Moreover, their hybrid compound, 3,5-di-bromo-thiophen-4,6-di-fluoro-benzothiazole 4b, showed the most potent anti-norovirus activity with a EC50 value of 0.53 µM (70-fold more potent than 1). Further investigation suggested that 4b might inhibit intracellular viral replication or the late stage of viral infection.
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Selecting the best quantitative PCR assay is essential to detect human norovirus genome effectively from clinical and environmental samples because no cell lines have been developed to propagate this virus. The real-time PCR methods for noroviruses GI (4 assays) and GII (3 assays) were evaluated using wastewater (n = 70) and norovirus-positive stool (n = 77) samples collected in Japan between 2012 and 2013. Standard quantitative PCR assays recommended by the U.S. Environmental Protection Agency, International Organization for Standardization, and Ministry of Health, Labour and Welfare, Japan, together with recently reported assays were included. Significant differences in positive rates and quantification cycles were observed by non-parametric analysis. The present study identifies the best assay for norovirus GI and GII to amplify norovirus genomes efficiently.
Article
Food‐ and waterborne viruses, such as human norovirus, hepatitis A virus, hepatitis E virus, rotaviruses, astroviruses, adenoviruses, and enteroviruses, are major contributors to all foodborne illnesses. Their small size, structure, and ability to clump and attach to inanimate surfaces make viruses challenging to reduce or eliminate, especially in the presence of inorganic or organic soils. Besides traditional wet and dry methods of disinfection using chemicals and heat, emerging physical nonthermal decontamination techniques (irradiation, ultraviolet, pulsed light, high hydrostatic pressure, cold atmospheric plasma, and pulsed electric field), novel virucidal surfaces, and bioactive compounds are examined for their potential to inactivate viruses on the surfaces of foods or food contact surfaces (tools, equipment, hands, etc.). Every disinfection technique is discussed based on its efficiency against viruses, specific advantages and disadvantages, and limitations. Structure, genomic organization, and molecular biology of different virus strains are reviewed, as they are key in determining these techniques effectiveness in controlling all or specific foodborne viruses. Selecting suitable viral decontamination techniques requires that their antiviral mechanism of action and ability to reduce virus infectivity must be taken into consideration. Furthermore, details about critical treatments parameters essential to control foodborne viruses in a food production environment are discussed, as they are also determinative in defining best disinfection and hygiene practices preventing viral infection after consuming a food product.
Article
Noroviruses cause significant global health burdens and waterborne transmission is a known exposure pathway. Chlorination is the most common method of disinfection for water and wastewater worldwide. The purpose of this study was to investigate the underlying causes for discrepancies in human norovirus (hNoV) resistance to free chlorine that have been previously published, and to assess hNoV GI and GII persistence during disinfection of municipal secondary wastewater (WW) effluent. Our results reveal that choice of hNoV purification methodology prior to seeding the viruses in an experimental water matrix influences disinfection outcomes in treatment studies. Common hNoV purification processes such as solvent extraction and 0.45-μm filtration were ineffective in removing high levels of organics introduced into water or wastewater samples when seeding norovirus positive stool. These methods resulted in experimental water matrices receiving an additional 190 mg/L as Cl2 of 15-s chlorine demand and approximately 440 mg/L as Cl2 of 30-min chlorine demand due to seeding norovirus positive stool at 1% w/v. These high organic loads impact experimental water chemistry and bias estimations of hNoV persistence. Advanced purification of norovirus positive stool using sucrose cushion ultracentrifugation and ultrafiltration reduced 15-s chlorine demands by 99% and TOC by 93% for loose (i.e. unformed diarrhea) stools. Using these methods, hNoV GI and GII persistence was investigated during free chlorination of municipal WW. A suite five of kinetic inactivation models was fit to viral reverse transcription-qPCR reduction data, and model predicted CT values for 1, 2, and 3 log10 reduction of hNoV GI in municipal WW by free chlorine were 0.3, 2.1, and 7.8 mg-min/L, respectively. Model predicted CT values for reduction of hNoV GII in WW were 0.4, 2.0, and 7.0 mg-min/L, respectively. These results indicate that current WW treatment plant disinfection practices employing free chlorine are likely protective for public health with regards to noroviruses, and will achieve at least 3-log reduction of hNoV GI and GII RNA despite previous reports of high hNoV resistance.
Article
Viral contamination can compromise the safety of water utilized for direct consumption, produce irrigation, and postharvest washing of produce. Zero-valent iron (ZVI) is used commercially for chemical remediation of water and has been demonstrated to remove some biological contaminants from water in laboratory and field studies. This study investigated the efficacy of ZVI to remove human norovirus surrogates, Tulane virus (TV) and murine norovirus (MNV), from water and to characterize the reversibility and nature of viral association with ZVI. Genomic material of TV and MNV recovered from the effluent of inoculated water treatment columns containing a 1:1 mixture of ZVI and sand was 2 and 3 log, respectively, less than that recovered from the effluent of treatment columns containing only sand. Elution buffers (citrate buffers, pH 4 and 7, and virus elution buffer, pH 9.5, with and without added 1 M NaCl) did not increase recovery of infectious TV and MNV from ZVI as compared with elution with water alone. TV-inoculated lettuce washed with water in the presence of ZVI yielded 1.5 to 2 log fewer infectious TV from washwater as compared with lettuce washed with water alone or in the presence of sand. These data demonstrate the enhanced removal of human norovirus surrogates, TV and MNV, from water by ZVI and provide indications that unrecovered viruses are not readily disassociated from ZVI by buffers of various pH and ionic strength. These findings warrant further investigation into larger-scale simulations of water remediation of viral contaminants for potential application in the treatment of water used for drinking, irrigation, and food processing.
Article
Ferrate(VI) (FeVIO42, Fe(VI)) is an emerging oxidant/disinfectant to treat a wide range of contaminants and microbial pollutants in wastewater. This study describes the inactivation of murine norovirus (MNV) by Fe(VI) in phosphate buffer (PB) and secondary effluent wastewater (SEW). The decay of Fe(VI) had second-order kinetics in PB while Fe(VI) underwent an initial demand followed by first-order decay kinetics in SEW. The Chick-Watson inactivation kinetic model, based on integral CT (ICT) dose, fitted well the inactivation of MNV in both PB and SEW. In PB, the values of the inactivation rate constant (kd) decreased with increase in pH, which was related to the reaction of protonated Fe(VI) species (HFeO4-) with MNV. Higher kd was observed in SEW than in PB. The inactivation of indigenous fecal coliforms (FC) in SEW was also measured. A two-population double-exponential model that accounted for both dispersed and particle-associated FC fitted well the inactivation data with determined kd and particle-associated inactivation rate constant (kp). Results show that Fe(VI) was more effective in inactivating dispersed FC than MNV. The MNV inactivation results obtained herein, coupled with the detailed modeling, provide important information in designing an Fe(VI) wastewater disinfection process.
Article
Introduction. The results of experimental studies on the comparative assessment of the effects of various doses of UV radiation on the survival of poliovirus type I LSc2ab, phage MS-2, hepatitis A viruses and their RNA in tap water are presented. Material and methods. Poliomyelitis viruses of type I strain LSc2ab (PV), viruses of hepatitis A, strain HAS-15 (HAV), phages MS-2, free RNA isolated from hepatitis viruses and poliomyelitis were introduced into model reservoirs with dechlorinated Moscow tap water. Water samples were taken from each tank and subjected to ultraviolet irradiation (UVR) with a wavelength of 254 nm with doses of 25, 40, 60, 80 and 100 mJ/cm2. PV titration was performed on a BGM monkey kidney cell transplant line; MS-2 phages were determined by the agar layer method using the E. coli K12F + Str. detector; determination of PV RNA and HAV was carried out on the Rotor GeneTM 6000 amplifier in RT-PCR reaction in real-time using appropriate test systems. Extraction and isolation of RNA from samples of PV and HAV were also performed using reagent kits of domestic and foreign production. Results. Ultraviolet irradiation in doses from 25 to 100 mJ/cm2 was shown to have a pronounced inhibitory effect on phages MS-2 and PV, determined by traditional methods in accordance with the methodological guidelines MUK 4.2.1018-01 and MUK 4.2.2029-05. At UVR doses of 80 and 100 mJ/cm2, complete inactivation of MS-2 and PV phages in water was noted. At the same time, these same doses of UVR had a less inhibitory effect on PVA, HAV RNA, as well as on isolated free PVA RNA/X and HAV, which were more stable and continued to be determined by RT-PCR in water at all doses of UVR, including 80 and 100 mJ/cm2. Conclusion. If only RNA viruses are detected in the treated drinking water and there are no other direct or indirect indices of viral contamination, it is impossible to unambiguously judge the extent of the potential epidemic hazard of the water body. This requires the development of reliable additional tests confirming the infectivity of viruses, determined only by RNA or DNA markers.
Chapter
Water is the main source of sustaining life. It is an indispensable need for flora and fauna alike. However, water is often contaminated by multidrug-resistant bacteria and various other contaminants. Disinfection methods like ozonation and chlorination fail to curtail these menace, often generating harmful by-products in this process. Photocatalysis, a subsidiary of advanced oxidation processes might have an important role to play in water decontamination. They are effective, do not generate by-products, and provide complete inactivation against these MDR strains and pollutants. The already existing photocatalysts like Titanium Dioxide and Zinc Oxide are being depleted to their core. So, newer and novel photocatalysts need to be developed with a more proficient, eco-friendly and biocompatible approach. This discussion aims to have a closer look at the existing disinfection techniques and the emerging players in the field of photocatalysis.
Article
Foodborne viral illnesses are frequent worldwide and costly for the society. Human norovirus is one of the most common causal agents. Although some norovirus genotypes can now be cultured, surrogates are still used for inactivation studies. The aim of this study was to evaluate the effects of different organic loads individually (artificial feces, real fecal matter, ASTM tripartite organic load, fetal bovine serum) on the efficacy of three highly used sanitization treatments (thermal inactivation, peracetic acid and sodium hypochlorite treatment) using murine norovirus 3 in solutions and surfaces. Based on plaque-forming units, we show that organic matter protects murine norovirus 3 against thermal inactivation (viral reduction of ~ 1 log compared to 2.67 with PBS). However, there was a low-level but significant protection against peracetic acid (viral reduction of ~ 2 log compared to 2.85 with PBS) and none in the presence of sodium hypochlorite. Our study showed that the tested organic matters do not behave similarly depending on the treatments, especially with heat treatments, which showed a higher protection. Furthermore, Feclone ™ artificial feces mimicked some aspect of real fecal matter and may be used instead. Our results will be helpful to researchers undertaking viral inactivation studies in which an organic matrix is used to simulate actual conditions of human norovirus environment.
Article
Norovirus (NoV) is the most common cause of infectious gastroenteritis in the world. Gastroenteritis caused by bacterial and parasitic pathogens is commonly linked to food sources, but the link between NoV and contaminated foods has been more difficult to establish. Even when epidemiological information indicates that an outbreak originated with food, the presence of NoV in the suspect product may not be confirmed. If food is found to contain a common strain of NoV that circulates widely in the community, it is not possible to use strain typing to link the contamination to patient cases. Although food is certainly implicated in NoV spread, there are additional person-to-person and fomite transmission routes that have been shown to be important. NoV has an extremely low infectious dose, is stable in the environment, and resists disinfection. Cell culture methods are not available, so viability cannot be determined. Finally, many NoV outbreaks originate with when an infected food handler contaminates ready-to-eat food, which can be interpreted as foodborne or person-to-person transmission. This review will discuss both the physical characteristics of NoVs and the available epidemiological information with particular reference to the role of foods in NoV transmission.
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Inactivation of infectious viruses during drinking water treatment is usually achieved with free chlorine. Many drinking water utilities in the United States now use monochloramine as a secondary disinfectant to minimize disinfectant by-product formation and biofilm growth. The inactivation of human adenoviruses 2, 40, and 41 (HAdV2, HAdV40, and HAdV41), coxsackieviruses B3 and B5 (CVB3 and CVB5), echoviruses 1 and 11 (E1 and E11), and murine norovirus (MNV) are compared in this study. Experiments were performed with 0.2 mg of free chlorine or 1 mg of monochloramine/liter at pH 7 and 8 in buffered reagent-grade water at 5 degrees C. CT values (disinfectant concentration x time) for 2- to 4-log(10) (99 to 99.99%) reductions in virus titers were calculated by using the efficiency factor Hom model. The enteroviruses required the longest times for chlorine inactivation and MNV the least time. CVB5 required the longest exposure time, with CT values of 7.4 and 10 mg x min/liter (pH 7 and 8) for 4-log(10) inactivation. Monochloramine disinfection was most effective for E1 (CT values ranged from 8 to 18 mg x min/liter for 2- and 3-log(10) reductions, respectively). E11 and HAdV2 were the least susceptible to monochloramine disinfection (CT values of 1,300 and 1,600 mg-min/liter for 3-log(10) reductions, respectively). Monochloramine inactivation was most successful for the adenoviruses, CVB5, and E1 at pH 7. A greater variation in inactivation rates between viruses was observed during monochloramine disinfection than during chlorine disinfection. These data will be useful in drinking water risk assessment studies and disinfection system planning.
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A virus concentration method using a cation-coated filter was developed for large-volume freshwater applications. Poliovirus type 1 (LSc 2ab Sabin strain) inoculated into 40 ml of MilliQ (ultrapure) water was adsorbed effectively to a negatively charged filter (Millipore HA, 0.45-μm pore size) coated with aluminum ions, 99% (range, 81 to 114%) of which were recovered by elution with 1.0 mM NaOH (pH 10.8) following an acid rinse with 0.5 mM H2SO4 (pH 3.0). More than 80% poliovirus recovery yields were obtained from 500-ml, 1,000-ml, and 10-liter MilliQ water samples and from tap water samples. This method, followed by TaqMan PCR detection, was applied to determine the presence of noroviruses in tap water in Tokyo, Japan. In a 14-month survey, 4 (4.1%) and 7 (7.1%) of 98 tap water samples (100 to 532 liters) contained a detectable amount of noroviruses of genotype 1 and genotype 2, respectively. This method was proved to be useful for surveying the occurrence of enteric viruses, including noroviruses, in large volumes of freshwater.
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Noroviruses (NoVs) are a leading cause of gastroenteritis worldwide and are recognized as the foremost cause of foodborne illness. Despite numerous efforts, routine cell cultures have failed to yield replicating NoV. This paper describes methods used to try to grow NoV in vitro in two laboratories. Cells (A549, AGS, Caco-2, CCD-18, CRFK, CR-PEC, Detroit 551, Detroit 562, FRhK-4, HCT-8, HeLa, HEC, HEp-2, Ht-29, HuTu-80, I-407, IEC-6, IEC-18, Kato-3, L20B, MA104, MDBK, MDCK, RD, TMK, Vero and 293) were cultured on solid or permeable surfaces. Differentiation was induced using cell culture supplements such as insulin, DMSO and butyric acid. In some cases, the cells and the NoV-containing stool samples were treated with bioactive digestive additives. Variables evaluated in cultivation experiments included the method of preparation of the virus inoculum, the genotype of the virus, conditions for maintenance of cell monolayers, additives in the maintenance medium and the method of inoculation of the cells. Serial blind passage studies were performed routinely. In addition to evaluation for CPE, evidence of virus replication was sought using immunofluorescent assays to detect newly produced viral capsid antigen and RT-PCR assays to detect the viral genome. Although some infected cultures remained NoV positive by RT-PCR for up to five passages and an occasional cell in a monolayer showed evidence of specific immunofluorescence, no reproducible NoV-induced CPE was observed and all RT-PCR results that were positive initially were negative following continued passaging. Thus, attempts to develop a method for the cultivation of NoV were unsuccessful.
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Noroviruses are understudied because these important enteric pathogens have not been cultured to date. We found that the norovirus murine norovirus 1 (MNV-1) infects macrophage-like cells in vivo and replicates in cultured primary dendritic cells and macrophages. MNV-1 growth was inhibited by the interferon-alphabeta receptor and STAT-1, and was associated with extensive rearrangements of intracellular membranes. An amino acid substitution in the capsid protein of serially passaged MNV-1 was associated with virulence attenuation in vivo. This is the first report of replication of a norovirus in cell culture. The capacity of MNV-1 to replicate in a STAT-1-regulated fashion and the unexpected tropism of a norovirus for cells of the hematopoietic lineage provide important insights into norovirus biology.
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Noroviruses (NoV) are the major cause of nonbacterial gastroenteritis. However, there is no published study to ascertain their survival on foodstuffs which are directly related to human health risk. In the present study, we developed a rapid, simple, and sensitive real-time nucleic acid sequence-based amplification (NASBA) combined with an enzymatic treatment for distinguishing infectious from noninfectious human NoV. The developed method was validated using spiked ready-to-eat food samples. When feline calicivirus (FCV) was used as a NoV surrogate in the preliminary assays, it appeared more sensitive to heat inactivation and enzymatic pretreatment than the human NoV. This suggests that FCV may not be an ideal model for studying NoV. Our results reveal clearly that the developed enzymatic pretreatment/real-time NASBA combination successfully distinguished the infectious from heat-inactivated NoV. Moreover, we demonstrate that NoV survived for at least 10 days on refrigerated ready-to-eat foods, such as lettuce and turkey. However, the survival rate was higher on turkey than on lettuce, probably because of their different surface natures. The approach developed in this study may be suitable for more in-depth studies of the persistence and inactivation of human NoV and may be applied to other nonculturable RNA viruses. Moreover, the evaluation of infectious NoV survival provided valuable information concerning its persistence on ready-to-eat food.
Article
The effects of heat (72°C) and UV-light (254nm) on the infectivity of murine norovirus-1 (MNV-1) and human norovirus (NoV) are reported. The infectivity of MNV-1 was measured using standard cell-culture plaque assays and was compared with a specific duplex RT-qPCR for MNV-1, which targets two fragments of the MNV genome, one 142bp (short-range, sRT-qPCR) and a second 4.6kb (long-range, loRT-qPCR) upstream from the reverse transcription (RT) priming site (poly-A tail). After the heat treatment of MNV neither the sRT- nor loRT-qPCR correlated with decreased infectivity as assessed by the plaque assay. However, after UV-exposure, the lo-qPCR showed decreased qPCR amplification, which became more pronounced with increased UV-exposure time, and reflected decreased infectivity as shown in the plaque assay. The sRT-qPCR amplification was not affected by UV-exposure. Similar results were obtained when challenging non-culturable human GI and GII NoV with UV-light. Using previously published RT-qPCR assays for GI and GII NoV, no decrease in RT-qPCR amplification was seen when using the respective reverse primers of the RT-qPCR assay in the RT reaction, whereas a significant decrease in qPCR amplification occurred when the RT reaction was primed at the poly-A tail about 2.3kb from the qPCR amplification site. The results indicate that, in contrast to RT-qPCR with a long-range RT, RT-qPCR with a short-range RT does not reflect genomic integrity and therefore viral infectivity. Furthermore, human NoV appears to be highly sensitive to UV-irradiation which could lead to more efficient decontamination procedures.
Article
We determined the disinfection efficiency of chlorine and chlorine dioxide (ClO(2)) using murine norovirus (MNV) and coliphage MS2 as surrogates for human norovirus. Experiments were performed in oxidant demand-free buffer (pH 7.2) at 5 degrees C and 20 degrees C. The extent of virus inactivation by a disinfectant was quantified using three different analytical methods: plaque, short template real-time TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR), and long template RT-PCR assays. Rapid inactivation of MNV by both chlorine and chlorine dioxide was observed by the plaque assay. According to the efficiency factor Hom model, Ct values of 0.314mg/Lmin and 0.247mg/Lmin were required for a 4-log reduction of MNV at 5 degrees C by chlorine and chlorine dioxide, respectively. Lower Ct values were required at 20 degrees C. Both long template and short template RT-PCR assays significantly underestimated the virus inactivation compared to the plaque assay. Our study demonstrates that adequate treatment of water with either chlorine or ClO(2) is likely to effectively control the waterborne transmission of human norovirus.
Article
The infectivity evaluation of noncultivatable viruses, such as human norovirus, is crucial to address needs for ensuring the safety in usage of water and marine products. In this work, we tested a new approach to evaluate viral particle integrity, in which oxidatively produced carbonyl groups on viral capsid protein were quantitatively detected. As a result, the decrease in the infectivity of human astrovirus, a representative enteric virus, positively correlated with the amount of oxidative damage on viral particles. Furthermore, when human norovirus was treated by 1 ppm free chlorine for 15 min, 49.93% of virions were recovered as oxidatively damaged particles, which represents a 5-fold increase over those treated by 0.5 ppm free chlorine for 15 min. The detection of the carbonylated viral particles could be a powerful tool for the evaluation of the decrease in the infectivity of noncultivatable viruses.
Article
A one-step reverse transcription quantitative real-time polymerase chain reaction (RT-QPCR) method in combination with RNase treatment and low copy number samples was developed in order to examine the effect of temperature on the ability of virus capsids to protect their RNA content. The method was applied to a non-cultivable virus (GII.4 norovirus) and Feline calicivirus vaccine strain F-9 (FCV) which is often used as a norovirus surrogate. Results demonstrated that FCV RNA is exposed maximally after 2min at 63.3 degrees C and this correlated with a greater than 4.5log reduction in infectivity as assessed by plaque assay. In contrast human GII.4 norovirus RNA present in diluted clinical specimens was not exposed maximally until 76.6 degrees C, at least 13.3 degrees C greater than that for FCV. These data suggest that norovirus possesses greater thermostability than this commonly used surrogate. Further, these studies indicate that current food processing regimes for pasteurisation are insufficient to achieve inactivation of GII.4 NoVs. The method provides a novel molecular method for predicting virus infectivity.
Article
In an effort to validate previous research suggesting remarkable resistance of norovirus to free chlorine disinfection, we characterized the disinfection response of purified and dispersed Norwalk virus (NV) by bench-scale free chlorine disinfection using RT-PCR for virus assays. The inactivation of NV by two doses of free chlorine (1 and 5mg/L) at pH 6 and 5 degrees C based on two RT-PCR assays was similar to that of coliphage MS2, but much faster than that of poliovirus 1. Despite the underestimation of virus inactivation by RT-PCR assays, the predicted CT values for NV based on RT-PCR assays are lower than the ones for most other important waterborne viruses and the CT guidelines for chlorine disinfection of viruses under the Surface Water Treatment Rule by the United States Environmental Protection Agency. Overall, the results of this study indicate that NV is not highly resistant to free chlorine disinfection as suggested by previous research and it is likely that NV contamination of drinking water can be controlled by adequate free chlorine disinfection practices with provision of proper pre-treatment processes before chlorination.
Article
We developed a new procedure for concentration of enteric viruses from water using a negatively charged membrane. Rinsing the membrane with 0.5 mM H2SO4 (pH 3.0) in order to elute cations prior to viral elution with 1 mM NaOH (pH 10.5) promoted poliovirus recovery yields from 33 to 95% when applied to pure water and 38 to 89% when applied to natural seawater from Tokyo Bay, Japan, respectively. This method showed average recovery yields of spiked poliovirus of 62% (n = 8) from 1 liter of artificial seawater. This method showed higher recovery yields (>61%) than that of the conventional method using positively charged membrane (6%) when applied to seawater. This method is also free from beef extract elution, which has an inhibitory effect in the subsequent viral genome detection by reverse transcription-PCR. Naturally occurring Norwalk viruses from 2 liters of Tokyo Bay water in winter and infectious enteroviruses from 2 liters of recreational coastal seawater in summer were detected by using this viral concentration method.
Article
We have developed an assay for the detection of Norwalk-like viruses (NLVs) based on reverse transcription-PCR (RT-PCR) that is highly sensitive to a broad range of NLVs. We isolated virus from 71 NLV-positive stool specimens from 37 outbreaks of nonbacterial acute gastroenteritis and sequenced the open reading frame 1 (ORF1)-ORF2 junction region, the most conserved region of the NLV genome. The data were subjected to multiple-sequence alignment analysis and similarity plot analysis. We used the most conserved sequences that react with diverse NLVs to design primers and TaqMan probes for the respective genogroups of NLV, GI and GII, for use in a real-time quantitative RT-PCR assay. Our method detected NLV in 99% (80 of 81) of the stool specimens that were positive by electron microscopy, a better detection rate than with the two available RT-PCR methods. Furthermore, our new method also detected NLV in 20 of 28 stool specimens from the same NLV-related outbreaks that were negative for virus by electron microscopy. Our new assay is free from carryover DNA contamination and detects low copy numbers of NLV RNA. It can be used as a routine assay for diagnosis as well as for elucidation of the epidemiology of NLV infections.
Article
Noroviruses are one of the major causes of viral gastroenteritis in Japan. A quantitative risk assessment was conducted to evaluate the health risk caused by this virus in drinking water. A Monte Carlo analysis was used to calculate both the probability of infection and the disease burden using disability-adjusted life years (DALYs). The concentration of noroviruses in tap water was estimated based on qualitative data and a most probable number (MPN) method with an assumed Poisson lognormal distribution. This numerical method was evaluated using two sets of available count data of Cryptosporidium: that collected from a river and that found in tap water in Japan. The dose-response relationships for noroviruses were estimated using assumed ID50 (10 or 100). The annual risk was higher than the US-EPA acceptable level (10(-4) [infection/ person-year]) but around the WHO level (10(-6) [DALYs/ person-year]). As suggested by others, since microbial concentrations are generally lognormally distributed, the arithmetic mean was directly related to the annual risk, suggesting that the arithmetic mean is more useful in representing the degree of microbial contamination than the geometric mean.