Article

Mechanisms of inactivation of hepatitis A virus in water by chlorine dioxide

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Abstract

In this study, to elucidate the mechanisms of inactivation of hepatitis A virus (HAV) by chlorine dioxide, cell culture, enzyme-linked immunosorbent assay (ELISA), and long-overlapping RT-PCR were used to detect the infectivity, antigenicity, and entire genome of HAV before and after disinfection. The results revealed the complete inactivation of infectivity after a 10-min exposure to 7.5mg of chlorine dioxide per liter; and the highest level of sensitivity in the 5'non-translated regions (5'NTR) (the sequence from bp 1 to 671), inactivation of which took as much time as the inactivation of infectivity of HAV by chlorine dioxide; the complete destruction of antigenicity after a 10-min exposure to 7.5mg of chlorine dioxide per liter. It is suggested that the inactivation mechanism of HAV by chlorine dioxide was due to the loss of the 5'NTR and/or destruction of the antigenicity, which is not similar to that of chlorine (Appl Environ Microbiol 68: 4951).

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... When they are treated with 1.0 mg/l of chlorine oxide, enveloped viruses are inactivated readily compared to non-enveloped viruses (Sanekata et al., 2010). The adherence of the virus to the host cell is prevented via the disinfection action on the proteins of the viral envelope, and consequently, cell invasion and infection were prevented (Li et al., 2004). According to Noss et al. (1986), the premise of the disinfection process is a viral protein component; inactivating the coat viral protein results in the inhibition of the virus capacity to attack the host cells. ...
... The effect of ClO 2 at an initial concentration of 5 mgl −1 was elucidated on HAV, and the disinfectant could not eliminate the infectivity after 60 min; however, the virus was completely inactivated after 10 min having increased the concentration to 7.5 mgl −1 . The 5′-non-translated region (5'NTR) of the virus's genome was damaged by the disinfectant, which hindered the replication, and interaction with viral proteins and prevented adherence to the host's cells (Li et al., 2004). A faster inactivation rate of 30 s at 0.8 mgl −1 and 5 min at 0.4 mgl −1 , respectively, for HAV was reported by the Department of Public Health of Parma (Li et al., 2004;Zoni et al., 2007). ...
... The 5′-non-translated region (5'NTR) of the virus's genome was damaged by the disinfectant, which hindered the replication, and interaction with viral proteins and prevented adherence to the host's cells (Li et al., 2004). A faster inactivation rate of 30 s at 0.8 mgl −1 and 5 min at 0.4 mgl −1 , respectively, for HAV was reported by the Department of Public Health of Parma (Li et al., 2004;Zoni et al., 2007). ...
Article
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Water contamination is a global health problem, and the need for safe water is ever-growing due to the public health implications of unsafe water. Contaminated water could contain pathogenic bacteria, protozoa, and viruses that are implicated in several debilitating human diseases. The prevalence and survival of waterborne viruses differ from bacteria and other waterborne microorganisms. In addition, viruses are responsible for more severe waterborne diseases such as gastroenteritis, myocarditis, and encephalitis among others, hence the need for dedicated attention to viral inactivation. Disinfection is vital to water treatment because it removes pathogens, including viruses. The commonly used methods and techniques of disinfection for viral inactivation in water comprise physical disinfection such as membrane filtration, ultraviolet (UV) irradiation, and conventional chemical processes such as chlorine, monochloramine, chlorine dioxide, and ozone among others. However, the production of disinfection by-products (DBPs) that accompanies chemical methods of disinfection is an issue of great concern due to the increase in the risks of harm to humans, for example, the development of cancer of the bladder and adverse reproductive outcomes. Therefore, this review examines the conventional disinfection approaches alongside emerging disinfection technologies, such as photocatalytic disinfection, cavitation, and electrochemical disinfection. Moreover, the merits, limitations, and log reduction values (LRVs) of the different disinfection methods discussed were compared concerning virus removal efficiency. Future research needs to merge single disinfection techniques into one to achieve improved viral disinfection, and the development of medicinal plant-based materials as disinfectants due to their antimicrobial and safety benefits to avoid toxicity is also highlighted.
... In previous studies, it was determined that ClO 2 inactivated PV1 and hepatitis A virus (HAV) primarily by disrupting the 5′-NCR of the viral genome. 24,27,28 Despite this finding, the relationship between EV71 infectivity and the integrity of the EV71 genome following ClO 2 treatment has yet to be unexplored. ...
... The supernatant was then assayed for infectious EV71 and found to contain 10 7.75 tissue culture infective doses (TCID 50 )/ml. 28 The viral suspension was stored at −70°C. Before use, the EV71 suspension was thawed, sonicated for 30 s at 20 kHz (150 W), and filtered through a 0.22 μm pore-size membrane to remove any large clumps or aggregates of virus. ...
... The residual chlorine and ClO 2 concentrations were both measured as previously described. 28 Disinfection Experiments. Microbial inactivation experiments were conducted in sterile 500 mL glass bottles containing sterile PBS buffer solution. ...
... Sanekata suggested that enveloped viruses are inactivated more easily than nonenveloped viruses when exposed to 1.0 mg/L of ClO 2 [14]. The disinfectant action on the enveloped proteins cause a failure of the viral attachment to the host cell, and so, the failure of cell invasion and infection [15]. About that, some authors carried out a study showing that ClO 2 inactivates the virus thanks to its reaction with amino acids like cysteine and tryptophan [16]. ...
... The action mechanism was found in the viral genome damage and/or viral proteins destruction. Li et al. assessed that the disinfectant damaged the 5 -nontranslated region (5 NTR) of the genome, blocking its replication and reacting with the viral proteins, stopping the interactions with the host cells [15]. The Department of Public Health of Parma reported a faster inactivation of HAV (only 30 s at a 0.8-mg/L concentration and 5 min at 0.4 mg/L) [15,28]. ...
... Li et al. assessed that the disinfectant damaged the 5 -nontranslated region (5 NTR) of the genome, blocking its replication and reacting with the viral proteins, stopping the interactions with the host cells [15]. The Department of Public Health of Parma reported a faster inactivation of HAV (only 30 s at a 0.8-mg/L concentration and 5 min at 0.4 mg/L) [15,28]. ...
Article
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A viral spread occurrence such as the SARS-CoV-2 pandemic has prompted the evaluation of different disinfectants suitable for a wide range of environmental matrices. Chlorine dioxide (ClO2) represents one of the most-used virucidal agents in different settings effective against both enveloped and nonenveloped viruses. This narrative synthesis is focused on the effectiveness of ClO2 applied in healthcare and community settings in order to eliminate respiratory transmitted, enteric, and bloodborne viruses. Influenza viruses were reduced by 99.9% by 0.5–1.0 mg/L of ClO2 in less than 5 min. Higher concentration (20 mg/L) eliminated SARS-CoV-2 from sewage. ClO2 concentrations from 0.2 to 1.0 mg/L ensured at least a 99% viral reduction of AD40, HAV, Coxsackie B5 virus, and other enteric viruses in less than 30 min. Considering bloodborne viruses, 30 mg/L of ClO2 can eliminate them in 5 min. Bloodborne viruses (HIV-1, HCV, and HBV) may be completely eliminated from medical devices and human fluids after a treatment with 30 mg/L of ClO2 for 30 min. In conclusion, ClO2 is a versatile virucidal agent suitable for different environmental matrices.
... Decomposition of NaOCl forms hypochlorous acid (NaOCl + H 2 O → HOCl + NaOH − ) and damages the nucleic acids and capsid proteins of viruses. Moreover, structures of virus particles can be altered in the inner and outer portions by application of NaOCl (Hirneisen et al., 2010;Li et al., 2004). Although NaOCl was ineffective against HAV at concentrations up to 1000 ppm during carrier tests in our study, standard efficacy was observed at concentrations of more than 200 ppm for 1 min in suspension tests. ...
... mg/L ClO 2 under low temperature (5 • C) conditions. In contrast, only 30 s was required to achieve the same reduction at a higher temperature (20 • C) compared to 5 • C. In a study by Li et al. (2004), HAV was exposed to 7.5 ppm ClO 2 for 10 min to inactivate HAV in water. However, exhaustive deterioration of viral capsid proteins after exposure to ClO 2 has been noted (Sigstam et al., 2013;Wigginton et al., 2012). ...
Article
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A carrier (stainless steel disc as a default carrier) testing method is very needed for use in the actual food-processing fields by following the standard guideline. Here, we aimed to compare the virucidal efficacy of four commercial liquid disinfectants, including sodium hypochlorite (NaOCl), chlorine dioxide (ClO2), and peracetic acid (PAA) against hepatitis A virus (HAV) following the OECD guideline protocol based on the quantitative carrier testing method and compared carrier testing results with the suspension testing results. The OECD method specifies a test for establishing whether a chemical disinfectant or a microbicide has a virucidal activity on hard non-porous surfaces. The antiviral efficacy was evaluated by plaque assays, and disinfectants were considered effective if the virus reduction was greater than or equal to 3 log10 (99.9% decrease) for carrier or 4 log10 (99.99% decrease) for suspension tests. Results indicated that ClO2 above 500 ppm and 50% ethanol were effective in the carrier test method. In contrast, more than 200 ppm NaOCl and 50 ppm ClO2 for all exposure times and 70% ethanol with contact for more than 5 min were effective in suspension tests. Treatment with PAA (80–2500 ppm) were not effective in carrier or suspension tests. Therefore, we recommend the use of more than 500 ppm ClO2 or 50% ethanol with exposure for 10 min to disinfect surfaces that may be contaminated with HAV. Thus, these results could be effective in establishing official antiviral efficacy testing methods and basic data.
... Variations in the chlorine sensitivities of different virus genome regions have been previously observed in ssRNA hepatitis A virus. 24 In that case, the 3′-and 5′-nontranslated regions reacted faster than other regions, as determined by RT-qPCR. 24 Various sensitivities to chlorine were also reported in different regions across the dsDNA genome of adenovirus. ...
... 24 In that case, the 3′-and 5′-nontranslated regions reacted faster than other regions, as determined by RT-qPCR. 24 Various sensitivities to chlorine were also reported in different regions across the dsDNA genome of adenovirus. 15 One possible explanation for the observed greater reactivity of certain genome regions over others is the enrichment of highly reactive nucleobases in those regions, as observed in the direct UVC photolysis of the human norovirus genome. ...
Article
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Free chlorine disinfection is widely applied to inactivate viruses by reacting with their biomolecules, which include nucleic acids, proteins, and lipids. Knowing the reactivities of viral genomes with free chlorine and the protection that encapsidation provides would ultimately help predict virus susceptibility to the disinfectant. The relative reactivities of different viral genome types and the impact of viral higher order structure with free chlorine are poorly characterized. Here, we studied the reactivity of viral genomes representing four genome types from virus particles with diverse structures, namely, (+)ssRNA (MS2), dsRNA (φ6), ssDNA (φX174), and dsDNA (T3) with free chlorine. We compared the reactivities of these viral nucleic acids when they were suspended in phosphate buffer solutions (naked forms) and when they were in the native virus particles (encapsidated forms). The reactivities of nucleic acids were tracked by polymerase chain reaction (PCR)-based assays. The naked dsDNA of T3 was the least reactive with free chlorine, with an average second order rate constant normalized by the number of bases in the measured regions (in M–1 s–1 b–1) that was 34×, 65×, and 189× lower than those of the dsRNA of φ6, ssRNA of MS2, and ssDNA of φX174, respectively. Moreover, different regions in the ssRNA genome of MS2 and the dsRNA genome of φ6 exhibited statistically different reaction kinetics. The genomes within virus particles reacted slower than the naked genomes overall, but the extent of these differences varied among the four viruses. The results on viral nucleic acid reactivity help explain different susceptibilities of viruses to inactivation by free chlorine and also provide a valuable comparison of the susceptibilities of different nucleic acids to oxidants.
... Une méthode d'inactivation est efficace lorsqu'elle empêche la réalisation d'au moins une fonction essentielle au cycle viral telle que la reconnaissance et la liaison aux récepteurs cellulaires, l'internalisation et la décapsidation, la réplication du génome puis l'assemblage et la libération de nouvelles particules. S'il est depuis longtemps connu que ces fonctions sont altérées par des dommages aux protéines et/ou au génome (O'Brien and Newman, 1979;Roy et al., 1981), les mécanismes moléculaires ont pu être approfondis ces quinze dernières années grâce au développement des outils de biologie moléculaire et des méthodes analytiques, dont quelques-unes sont reportées dans le Tableau 8 (Jin et al., 2012(Jin et al., , 2013Li et al., 2004;Page et al., 2010;Sigstam et al., 2013;Simonet and Gantzer, 2006a;Wigginton et al., 2012a). ...
... De plus, à la différence du chlore, il provoque également une destruction complète de l'antigénicité. L'inactivation du VHA peut donc être liée à l'atteinte des protéines de capsides et/ou à la dégradation du génome (Li et al., 2004). D'autres travaux sont nécessaires pour une meilleure compréhension des contributions respectives des altérations génomiques et protéiques, qui semblent dépendre des virus considérés. ...
Thesis
Les virus entériques sont l’une des premières causes de gastro-entérites d’origine hydrique. Ils sont excrétés en grand nombre dans les selles et ne sont pas éliminés par les stations de traitement des eaux usées, dont les effluents sont la principale source de contamination des ressources hydriques, qui sont parfois utilisées pour la production d’eau potable. Ces virus sont particulièrement résistants aux traitements de désinfection, et leur génome est parfois détecté dans l’eau potable produite. Il a récemment été démontré que des interactions avec le microbiote intestinal au sein de l’hôte favorisent l’infectivité, pathogenèse et la stabilité de certains virus entériques (entérovirus, norovirus). Dans les milieux hydriques, ils peuvent se retrouver au voisinage d’une grande diversité d’éléments biotiques ou abiotiques, particulaires ou dissous, qui pourraient avoir des conséquences sur leur survie. Ces travaux apportent de nouveaux éléments de réflexion concernant les conséquences des interactions entre la matière organique et les virus entériques sur leur persistance dans les environnements hydriques et l’efficacité de traitements d’inactivation. L’impact de plusieurs composants microbiens sur l’inactivation de quatre sérotypes d’entérovirus a été analysé. D’importants effets protecteurs, ont été mis en évidence dans le cas des traitements d’inactivation ciblant la capside virale (chaleur, chlore). Un effet sérotype-dépendant a de plus été démontré. Dans un deuxième temps, il a été montré que la matière organique dissoute hydrophobe des eaux de surface confère au Coxsackievirus B5 une protection vis-à-vis de la chaleur en stabilisant la capside. La persistance des interactions avec la matière organique dissoute s’est révélée être liée à son hydrophobicité. Enfin, une expérience d’évolution virale sous pression de sélection thermique a révélé que les interactions des virus avec leur environnement participent à la dynamique d’évolution des espèces virales en favorisant leur stabilité génomique. Ainsi l’interaction avec le lipopolysaccharide entraine une levée de la pression de sélection exercée par la température. L’ensemble des résultats indique que la capacité des entérovirus à interagir avec certains types de matières organiques est susceptible d’augmenter leur persistance dans les milieux hydriques et au cours des traitements de désinfection, leur conférant dans certaines conditions un avantage sélectif. Les connaissances acquises sur l’inactivation virale en milieu hydrique pourraient donc surestimer les abattements viraux réels, et nécessiteraient peut-être d’être revisitées en prenant en compte l’existence de telles interactions.
... Many factors have been found to exert great impacts on virus inactivation rates such as ClO 2 dosage, pH, and temperature (Berman and Hoff 1984;Chen and Vaughn 1990;Hornstra et al. 2011;Thurston-Enriquez et al. 2005). The mechanisms of inactivation of virus by ClO 2 include the disruption of the virus protein or the damage of genome (Jin et al. 2013(Jin et al. ,2012Li et al. 2004;Sigstam et al. 2013;Wigginton et al. 2012). Understanding the virus inactivation kinetics upon ClO 2 disinfection is a pressing need in environmental engineering for ensuring sufficient disinfectant doses. ...
... However, in enteroviruses such as poliovirus, enterovirus 71 and hepatitis A virus, ClO 2 has been proposed to act on the viral genome. Specifically, the inactivation by ClO 2 is caused by damage in the 5′ noncoding region within the genome, which is necessary for the formation of new virus particles within the host cell (Jin et al. 2013(Jin et al. , 2012Li et al. 2004). Moreover, it has been reported that although protein damage plays an important role in inactivation of poliovirus, inactivation is ultimately attributed to viral RNA damage (Alvarez and O'Brien 1982;Simonet and Gantzer 2006). ...
Article
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Chlorine dioxide (ClO2), an alternative disinfectant to chlorine, has been widely applied in water and wastewater disinfection. This paper aims at presenting an overview of the inactivation kinetics and mechanisms of ClO2 with viruses. The inactivation efficiencies vary greatly among different virus species. The inactivation rates for different serotypes within a family of viruses can differ by over 284%. Generally, to achieve a 4-log removal, the exposure doses, also being referred to as Ct values (mutiplying the concentration of ClO2 and contact time) vary in the range of 0.06–10 mg L−1 min. Inactivation kinetics of viruses show two phases: an initial rapid inactivation phase followed by a tailing phase. Inactivation rates of viruses increase as pH or temperature increases, but show different trends with increasing concentrations of dissolved organic matter (DOM). Both damages in viral proteins and in the 5′ noncoding region within the genome contribute to virus inactivation upon ClO2 disinfection.
... Incubating the latex sap with SaV significantly reduced the infectivity but not the viral RNA titers (Fig. 4), suggesting that the latex sap affected the viral capsids but not the genomes. Ag-ELISA has been used previously to show the negative effects of disinfectants on virus antigenicity (33,34). Using Ag-ELISA, we showed that the latex sap affected the antigenicity of SaV (Fig. 5). ...
Article
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Noroviruses are the leading cause of food-borne outbreaks, including those that involve lettuce. The culturable porcine sapovirus (SaV) was used as a norovirus surrogate to study the persistence and the potential transfer of the virus from roots to leaves and from outer to inner leaves of lettuce plants. Treatment of lettuce with SaV was done through the roots of young plants, the soil, or the outer leaves of mature plants. Sampling of roots, xylem sap, and inner and outer leaves followed by RNA extraction and SaV-specific real-time reverse transcription (RT)-PCR was performed at 2 h and on postinoculation days (PID) 2, 5, 7, 14, and/or 28. When SaV was inoculated through the roots, viral RNA persisted on the roots and in the leaves until PID 28. When the virus was inoculated through the soil, viral RNA was detected on the roots and in the xylem sap until PID 14; viral RNA was detected in the leaves only until PID 2. No infectious virus was detected inside the leaves for either treatment. When SaV was inoculated through the outer leaves, viral RNA persisted on the leaves until PID 14; however, the virus did not transfer to inner leaves. Infectious viral particles on leaves were detected only at 2 h postinoculation. The milky sap (latex) of leaves, but not the roots' xylem sap, significantly decreased virus infectivity when tested in vitro. Collectively, our results showed the transfer of SaV from roots to leaves through the xylem system and the capacity of the sap of lettuce leaves to decrease virus infectivity in leaves.
... Chlorine dioxide (CD), which is a water-soluble, yellow gas at room temperature, exists as a relatively stable free radical and is a very strong oxidant agent [1][2][3]. Therefore, when dissolved in water, CD has a potent antimicrobial activity against bacteria and viruses in vitro [4][5][6][7]. ...
Article
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Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations. CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed. Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs. CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human.
... However, the uncertainty of the germicidal mechanism of chlorine dioxide has restricted its application in a more extensive field. Some authors have attempted to elucidate the biocidal mechanisms of ClO 2 and have concluded that ClO 2 could cause series of damage, such as content leakage (Zhang et al. 2007;Wei et al. 2008), protein and nucleic acid denaturation Noss et al. 1986;Li et al. 2004;Cho et al. 2010;Simonet and Gantzer 2006), and morphological alteration (Chen et al. 2002;Wang et al. 2010). However, there is still a lack of understanding on the major target site of ClO 2 interaction with microorganisms. ...
Article
The fungicidal mechanism of chlorine dioxide on Saccharomyces cerevisiae was investigated. During S. cerevisiae inactivation by ClO2, protein, DNA, and ion leakage, enzyme activity, genomic DNA structure, and cell ultrastructure were examined. Protein and DNA leakages were not observed, while ion leakages of K+, Ca2+, and Mg2+ were detected and were related to the inactivation rate. The glucose-6-phosphate dehydrogenase, citrate synthase, and phosphofructokinase activities were inhibited and were also correlated with the inactivation rate. Genomic DNA structure was not damaged except for an extremely high ClO2 concentration (100 mg L-1). Electron micrographs showed that cell surface damage was pronounced and disruption in inner cell components was also apparent. The ion leakage, the inhibition of key enzyme activities of metabolic pathway, and the alteration of cell structure were critical events in S. cerevisiae inactivation by ClO2.
... It can effectively kill most microorganisms, including bacteria, fungi, algae, viruses, parasites, and is a high effective disinfectant internationally recognized [19][20][21][22][23][24] . ...
Article
The inhibitory effect and its virulence of chlorine dioxide (ClO2) against dry rot of potato were investigated. Potatoes were treated by ClO2, then observed for indoor bioassay, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the morphology and ultrastructure of hyphae, and evaluated the control efficiency of ClO2 on potato tuber (LK99) dry rot by F. sulphureum pre-treatment. The results showed that the pathogen of potato dry rot was sensitive to ClO2, the virulence of regression of y = 5.05 + 7.308x, EC50 and EC90 were 0.3490 and 0.6261 respectively, the treatment of ClO2 could significantly inhibit the spore germination and mycelium growth of F. sulphureum, which was in a concentration-dependent manner, SEM and TEM observed that the morphology and ultrastructure of F. sulphureum hyphae were regularly damaged by ClO2, in vivo experiment further indicated that ClO2 could effectively control the dry rot of potato tubers with F. sulphureum, and ClO2 at the concentration of 0.75 ug/mL could significantly reduce the incidence of potato tuber dry rot and lesion expansion rate. The study showed that ClO2 could greatly against the pathogen of F. sulphureum, which could provide a scientific theoretical basis for the safe and efficient application of ClO2 in the prevention and control of potato diseases after harvest. © 2017, Chinese Society of Agricultural Engineering. All rights reserved.
... An alternative molecular approach to assess virus infectivity is the analysis of long target viral genome regions. The rationale behind this "long template" RT-PCR strategy is that the integrity of viral genome may correlate with virus infectivity (Allain et al. 2006;Li et al. 2004;Simonet and Gantzer 2006;Wolf et al. 2009). The fact that viral inactivation does not necessarily compromise genome integrity, however (e.g., when inactivation occurs through the degradation of surface proteins), limits the applicability of this strategy. ...
Chapter
Enteric viruses are the causes of many sporadic cases and outbreaks originating from contaminated water. Valid and reproducible methods for the detection of waterborne viral pathogens are crucial in order to determine the extent of contamination, the types of pathogens involved and the correlation between viral contamination and environmental factors. Strategies have been developed to overcome the difficulties associated with virological analysis of water samples. Various assays are available for the detection of the major pathogenic viruses potentially present in urban sewage, drinking or recreational waters. Monitoring of sewerage systems provides valuable epidemiological information regarding serotypes circulating in the community.
... La eficiencia de compuestos clorados como el hipoclorito de sodio para la inactivación del VHA es relativa teniendo en cuenta que en escenarios ambientales las partículas virales se asocian a la materia orgánica presente en el medio, lo que dificulta la inactivación (6,(31)(32)(33). En Colombia según la resolución 2115 del 2007 el valor de cloro residual libre en el agua para consumo humano es admisible en un rango de 0,3 a 2,0 mg/L. ...
Article
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Hepatitis A virus infection is a global public health problem. The virus has a wide range of distribution and it is the main cause of acute hepatitis transmitted by the enteric route in Latin America. The viral particle is stable under environmental conditions and conserves its infectivity for several weeks, enabling its transmission by contaminated water and food. Worldwide, different epidemiological patterns have been identified, which may change over time by modification of social and economic variables in the population such as vaccination and the improvement of hygiene and primary health conditions. This leaves new populations susceptible to infection. In Latin America the circulation of genotype I and subgenotypes A and B has been described, but more research is needed to provide the knowledge needed to manage the prevention and control plans for the worldwide reduction of the prevalence of infection. For this paper, a literature review was performed on the SciELO, PubMed and ScienceDirect databases under the search terms "Hepatitis A", "Epidemiology," "Seroprevalence" and "Infection." From the results obtained, only papers published in English and Spanish to describe epidemiological and molecular studies of interest in Latin America were included.
... Viruses are highly diverse in their structures, and virus inactivation mechanisms are often contradictory or equivocal. It has been suggested that the inactivation mechanism of hepatitis A virus (a picornavirus) by ClO 2 was due to the loss of the 5= untranslated region of the genome and/or receptor-binding domain destruction on the capsid (53). It was also found that ClO 2 inactivated poliovirus, another picornavirus, primarily by disrupting a 40-to 80-nucleotide sequence in the 5=-noncoding region of the genome (54). ...
Article
Acute gastroenteritis caused by human norovirus is a significant public health issue. Fresh produce and seafood are examples of high-risk foods associated with norovirus outbreaks. Food contact surfaces also have the potential to harbor noroviruses if exposed to fecal contamination, aerosolized vomitus, or infected food handlers. Currently, there is no effective measure to decontaminate norovirus on food contact surfaces. Chlorine dioxide (ClO2) gas is a strong oxidizer and is used as a decontaminating agent in food processing plants. The objective of this study was to determine the kinetics and mechanism of ClO2 gas inactivation of a norovirus surrogate, murine norovirus 1 (MNV-1), on stainless steel (SS) coupons. MNV-1 was inoculated on SS coupons at the concentration of 107 PFU/coupon. The samples were treated with ClO2 gas at 1, 1.5, 2, 2.5, and 4 mg/liter for up to 5 min at 25°C and a relative humidity of 85%, and virus survival was determined by plaque assay. Treatment of the SS coupons with ClO2 gas at 2 mg/liter for 5 min and 2.5 mg/liter for 2 min resulted in at least a 3-log reduction in MNV-1, while no infectious virus was recovered at a concentration of 4 mg/liter even within 1 min of treatment. Furthermore, it was found that the mechanism of ClO2 gas inactivation included degradation of viral protein, disruption of viral structure, and degradation of viral genomic RNA. In conclusion, treatment with ClO2 gas can serve as an effective method to inactivate a human norovirus surrogate on SS contact surfaces.
... Nevertheless, the mechanism of microbial inactivation by ClO2 has not been clearly clarified as lethal incidences are usually associated with complicated processes. Some authors have attempted to elucidate the biocidal mechanisms of ClO2 and have concluded that ClO2 could cause series of damage, such as content leakage (Zhang et al., 2007;Wei et al., 2008), protein and nucleic acid denaturation Li et al., 2004;Cho et al., 2010;Simonet and Gantzer, 2006), and morphological alteration (Chen et al., 2002;Wang et al., 2010). However, there is still a lack of understanding on the major target site of ClO2 interaction with microorganisms. ...
Article
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The mechanism of Fusarium tricinctum (Corda) Sacc. spore inactivation by chlorine dioxide (ClO2) was investigated. During F. tricinctum spore inactivation by ClO2, protein, DNA, and metal ion leakage, enzyme activity, and cell ultrastructure were examined. Protein and DNA leakages were not detected, while there were metal ion leakages of K+, Ca2+, and Mg2+, which were well-correlated with the inactivation rate. The enzyme activities of glucose-6-phosphate dehydrogenase, citrate synthase, and phosphofructokinase were inhibited and were also well-correlated with the inactivation rate. Electron micrographs showed the ultrastructural modifications of spores and demonstrated that spores were heavily distorted and collapsed from their regular structure. Spore surface damage and disruption in inner components was also severe. The metal ion leakage, the inhibition of enzyme activities, and the damage of spore structure were significant in F. tricinctum spore inactivation by ClO2.
... Sularda HAV'ın inaktivasyonunda 5 mg/L klor dioksite 60 dakika maruz bırakıldığında virüs sayısında 3.99 log azalma olduğu belirtilmiştir (57). Ayrıca HAV'ın 10 dakika 5, 10 ve 20 mg klora maruz bırakıldığında ise sırasıyla; %24.2, %94. ...
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Gıda kaynaklı viral enfeksiyonlar, viral gastroenteritler ve viral hepatitler (Hepatit A ve Hepatit E) olmak üzere iki gruba ayrılmaktadır. Gıda kaynaklı viral hepatitlerden, Hepatit A virüsü Picornaviridae ailesi, Hepatovirüs genusunda, Hepatit E ise Hepeviridae ailesi, Hepevirüs genusunda yer almaktadır. Gıda kaynaklı viral enfeksiyonlarda en yaygın bulaşma yolu fekal-oral olmakla birlikte, kan ve kan ürünleriyle ve kişiden kişiye temas yoluyla da bulaşabilmektedirler. Hepatit A'dan farklı olarak, Hepatit E virüsü zoonoz bir virüstür ve rezervuar hayvanlardan insanlara bulaşabilir. Dünya'da her yıl 1.43 milyon insanda Hepatit A enfeksiyonu görülmekte ve Hepatit A bakımından yüksek düzeyde endemik bölgelerde (Afrika, Asya, Orta ve Güney Amerika) 10 yaşın altındaki çocukların %90'dan fazlasının seropozitif olduğu bildirilmektedir. Hepatit E gelişmekte olan ülkelerde akut viral hepatitlerin %50'den fazlasından sorumlu tutulmaktadır. Hepatit A vakalarının yaklaşık %50'sinde enfeksiyonun kaynağı bulunamamaktadır. Hepatit A ve E'nin gıdalardan elimine edilmesi için yapılan çalışmalarda ısıl işlem uygulamasının Hepatit A'yı inaktive etmekte etkili olduğu, dondurma yönteminin ise uygun bir yöntem olmadığı belirtilmektedir. Hepatit E'nin gıdalarda inaktivasyonu için yeterli bilgiler olmamasına rağmen, etkenin Hepatit A'dan daha az dayanıklı olduğu bildirilmektedir. Gıda kaynaklı Hepatit A ve E enfeksiyonlarından korunmak için öncelikle her iki etkenin de gıdalarda elimine edilmesine yönelik daha ayrıntılı çalışmalara ihtiyaç duyulmaktadır. Anahtar Kelimeler: Hepatit A, Hepatit E, viral hepatit, gıda güvenliği Foodborne Viral Hepatitis and Food Safety Food-borne viral infections are divided into two groups as viral gastroenteritidis and viral hepatitis (Hepatitis A and E). Hepatitis A virus is a member of Hepatovirus genus of Picornaviridea family while Hepatitis E virus is classified under Hepevirus genus of the Hepeviridea family. The most common route of transmission of food-borne viral infections is the fecal-oral route. In addition, transmission via blood and blood products, person-to-person contact have been reported. Unlike from HAV, Hepatitis E virus is a zoonotic virus and can be transmitted to human by reservoir animals. Approximately 1.43 million people has been infected with Hepatitis A every year in the World. More than 90% of children younger than 10 years of age have been reported to be seropositive in highly-HAV endemic regions (Africa, Asia, centraland South America). Hepatitis E is responsible for more than 50% of the acute hepatitis cases in developing countries. In addition, sources of more than 50% of the Hepatitis A cases remain unknown. Results of studies to inactivate the Hepatitis A and E viruses from foods indicate that heat treatment is effective for eliminating Hepatitis A while freezing is ineffective. Although there are limited data about the inactivation of Hepatitis E, it has been known that Hepatitis E is less resistant to adverse conditions than Hepatitis A. In order to establish effective control measures for elimination of food borne viral Hepatitis and Hepatitis E infections, more detailed investigations are required.
... For example, Li et al. suggested that the destruction of antigenicity was partly responsible for the inactivation of hepatitis A virus. 40 Similarly, Simonet and Gantzer observed a discrepancy between poliovirus infectivity loss obtained by cell culture and genome decay measured by real-time PCR, suggesting an important role of protein damage in inactivation. 42 In contrast, Alvarez and O'Brien also observed reaction of ClO 2 with the capsid of poliovirus, but reported that the critical target was viral RNA. ...
Article
Waterborne viruses can exhibit resistance to common water disinfectants, yet the mechanisms that allow them to tolerate disinfection are poorly understood. Here, we generated echovirus 11 (E11) with resistance to chlorine dioxide (ClO2) by experimental evolution, and we assessed the associated genotypic and phenotypic traits. ClO2 resistance emerged after E11 populations were repeatedly reduced (either by ClO2-exposure or by dilution) and then regrown in cell culture. The resistance was linked to an improved capacity of E11 to bind to its host cells, which was further attributed to two potential causes: first, the resistant E11 populations possessed mutations that caused amino acid substitutions from ClO2-labile to ClO2-stable residues in the viral proteins, which likely increased the chemical stability of the capsid toward ClO2. Second, resistant E11 mutants exhibited the capacity to utilize alternative cell receptors for host binding. Interestingly, the emergence of ClO2 resistance resulted in an enhanced replicative fitness compared to the less resistant starting population. Overall this study contributes to a better understanding of the mechanism underlying disinfection resistance in waterborne viruses, and processes that drive resistance development.
... In contrast, Simonet and Gantzer (2006), who worked with high ClO 2 exposures (5 mg/L during 120 min), reported that viral RNA did degrade, but did not fully account for inactivation. Genome damage, specifically damage to the 5 ′ non-coding region, was found to be the main target for the treatment of enterovirus 71 and Hepatitis A virus at ClO 2 exposures of 13.5 mg/L * min or higher (Li et al., 2004;Jin et al., 2013). These authors also reported a similar finding for the inactivation of poliovirus by lower ClO 2 exposures (0.1-1.2 mg/L during 1-12 min) (Jin et al., 2012). ...
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The emergence of waterborne viruses with resistance to disinfection has been demonstrated in the laboratory and in the environment. Yet, the implications of such resistance for virus control remain obscure. In this study we investigate if viruses with resistance to a given disinfection method exhibit cross-resistance to other disinfectants. Chlorine dioxide (ClO2)- or UV-resistant populations of echovirus 11 were exposed to five inactivating treatments (free chlorine, ClO2, UV radiation, sunlight, and heat), and the extent of cross-resistance was determined. The ClO2-resistant population exhibited cross-resistance to free chlorine, but to none of the other inactivating treatments tested. We furthermore demonstrated that ClO2 and free chlorine act by a similar mechanism, in that they mainly inhibit the binding of echovirus 11 to its host cell. As such, viruses with host binding mechanisms that can withstand ClO2 treatment were also better able to withstand oxidation by free chlorine. Conversely, the UV-resistant population was not significantly cross-resistant to any other disinfection treatment. Overall, our results indicate that viruses with resistance to multiple disinfectants exist, but that they can be controlled by inactivating methods that operate by a distinctly different mechanism. We therefore suggest to utilize two disinfection barriers that act by different mechanisms in order to control disinfection-resistant viruses.
... If virus inactivation by some disinfectants is based on viral genomic damage, molecular techniques have been hypothesized to be able to effectively evaluate the disinfection effect since these techniques depend strictly on the integrity of the target nucleic acid as template. If specific regions of the genome harbor sequences sensitive to some disinfectants, as suggested in the literature (Li et al. 2004), evaluation of the disinfection effect would be feasible by using molecular techniques targeting these specific sequences. EMA/ PMA-qPCR has shown similar results to culture-based infectivity tests for chlorine but not for heat-inactivation and UV disinfection (Leifels et al. 2015). ...
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Continuous research in the field of water and health is important to ensure high standards of hygiene and to improve microbial risk assessment and water management. Various waterborne outbreaks induced by pathogenic bacteria, viruses and protozoa have been reported in recent decades. Pathogens derived from human and animal feces have been played frequently a key role in contaminations of freshwater. Reasons for the presence of pathogens in drinking water systems are insufficient wastewater treatment, contaminated raw water or damaged water supply systems. Numerous routes of transmission and the distribution of individual pathogens by raw water and drinking water constitute potential hazards to public health. Recently, different research activities have been initiated in Germany, which focus on the examination of pathogens in water to establish a modern microbial risk assessment according to the high-tech strategy employed by the federal government. This review article provides a compilation of the pathogens that are important in German water bodies (wastewater, surface water, groundwater, and drinking water) and includes coverage of German research on pathogens and technologies for reducing these pathogens in water, challenges to research, and recent developments in concentration and detection methods for pathogens. Finally, current knowledge gaps and ongoing research questions are highlighted.
... Thus, ClO 2 is considered as a promising agent in activating viruses with genome repair mechanisms such as double-stranded DNA viruses (Wigginton et al., 2012). During the inactivation of infectivity of HAdV, the destruction of the antigenicity and damaging of the 5 ′ nontranslated regions (the sequence from bp 1 to 671) of the genome occurred, suggesting that ClO 2 reacted with viral capsid protein to inhibit HAV from attaching to the host cells or uncoating or penetrating (Li et al., 2004). ...
Article
As the coronavirus disease 2019 continues to spread globally, its culprit, the severe acute respiratory syndrome coronavirus 2 has been brought under scrutiny. In addition to inhalation transmission, the possible fecal-oral viral transmission via water/wastewater has also been brought under the spotlight, necessitating a timely global review on the current knowledge about waterborne viruses in drinking water treatment system – the very barrier that intercepts waterborne pathogens to terminal water users. In this article we reviewed the occurrence, concentration methods, and control strategies, also, treatment performance on waterborne viruses during drinking water treatment were summarized. Additionally, we emphasized the potential of applying the quantitative microbial risk assessment to guide drinking water treatment to mitigate the viral exposure risks, especially when the unregulated novel viral pathogens are of concern. This review paves road for better control of viruses at drinking water treatment plants to protect public health.
... In addition, the denaturation of viral proteins has been reported to be involved Frontiers in Plant Science | www.frontiersin.org in the inactivation of human rotavirus (Xue et al., 2013). ClO 2 damages the 5' non-coding region in the viral genome that is necessary for formation of new virus particles within the host cells (Li et al., 2004;Jin et al., 2013). Furthermore, RNA damage, in addition to protein damage, has been attributed to the inactivation of poliovirus (Simonet and Gantzer, 2006). ...
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Maintaining microbial safety and quality of fresh fruits and vegetables are a global concern. Harmful microbes can contaminate fresh produce at any stage from farm to fork. Microbial contamination can affect the quality and shelf-life of fresh produce, and the consumption of contaminated food can cause foodborne illnesses. Additionally, there has been an increased emphasis on the freshness and appearance of fresh produce by modern consumers. Hence, disinfection methods that not only reduce microbial load but also preserve the quality of fresh produce are required. Chlorine dioxide (ClO2) has emerged as a better alternative to chlorine-based disinfectants. In this review, we discuss the efficacy of gaseous and aqueous ClO2 in inhibiting microbial growth immediately after treatment (short-term effect) versus regulating microbial growth during storage of fresh produce (long-term effect). We further elaborate upon the effects of ClO2 application on retaining or enhancing the quality of fresh produce and discuss the current understanding of the mode of action of ClO2 against microbes affecting fresh produce.
... These different responses suggest that even minor variations in structural or genomic components can have a marked impact on viral resistance to inactivation. It has been demonstrated that exposure to inactivating oxidants and radiation can result in modifications to viral proteins (Sano et al. 2009;Hotze et al. 2009;Wigginton et al. 2010) and nucleic acids (Nuanualsuwan et al. 2002;Li et al. 2004), leading to inactivation of viruses. Sunlight-mediated inactivation may not be the most effective route to protozoan and helminthic disinfection. ...
Article
Wastewater stabilization ponds (WSPs) have been proven to be economical alternatives to conventional wastewater treatment technologies due to their unique advantages including ease of operation, minimal energy input, and minimal maintenance requirements. Their reported high pathogen removal efficiencies have made WSPs a popular choice for wastewater treatment, especially as tertiary lagoons. This paper provides a critical overview of the various disinfection processes and mechanisms that occur in WSPs. A thorough review of the removal or attenuation mechanisms for bacterial, viral, protozoan, and helminthic pathogens is presented. Factors that impact the removal efficiency of pathogenic organisms may include sunlight, pH, dissolved oxygen, temperature, sedimentation, attachment, hydraulic retention time, pond depth, predation and nutrient availability; the relationship between these factors is also discussed. The purpose of this review paper is to utilize the current understanding of pathogen removal mechanisms in pond systems to improve the operation and design of WSPs, and more importantly, to provide guidance for the definition of regulations with respect to pathogen removal in eco-engineered wastewater treatment systems such as WSPs.
... Bleach is probably the most common disinfectant used in food industries, because it acts quickly and efficiently and because of its low cost (Fraisse et al. 2011;Seymour and Appleton 2001). Chlorine Dioxide is known for its antiviral properties such as acting on viral nucleic acids and proteins (Li et al. 2004). The following results concerning synthetic chemical agents will be presented in Table 1. ...
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Fresh foods like fruits, vegetables and shellfish are potential sources for viral infections such as human norovirus (NoV). Chemical treatment like chlorination is a well-known process for food pathogens and virus elimination. However, with the increase of the consumer demand for less toxic treatment, the use of natural antimicrobials like essential oils from spice or plants, fruit extracts, and cold pasteurization treatments (fermentation, irradiation, ozonation and high pressure) could be considered. The aim of this review is to discuss these technologies and their efficacy to eliminate NoV on the surface of fresh food.
... 1,2) There are many theories about its mechanism of action, including cell membrane destruction, 3,4) protein inactivation, 5) and viral DNA damage. 6) Due to its effectiveness against viruses and bacteria, it has been used not only in water and wastewater treatment, but has also been considered for environmental and food disinfection or medical applications. [7][8][9][10][11] However, chlorine dioxide gas is highly toxic, and the radicals that are responsible for the reaction are highly reactive. ...
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Matching transformation system (MA-T) is an on-demand aqueous chlorine dioxide solution. It is a disinfectant developed to maximize the safety of chlorine dioxide radical in water and its effectiveness against various microorganisms. In this study, we examined the safety and effectiveness of MA-T for its use in various infectious disease countermeasures, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and consider if MA-T can be implemented in society. To validate the safety of MA-T, we conducted safety tests and efficacy tests in accordance with GLP-based reliability criteria. To evaluate the efficacy, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) confirmation tests against various bacteria, and virus inactivation test against various viruses including SARS-CoV-2 by TCID50 method were performed. The results of safety tests showed that MA-T was at least as safe as Japanese tap water. As a result of efficacy tests for microorganisms, MA-T was effective against many bacteria. Efficacy tests for virus showed that MA-T inactivates SARS-CoV-1, Middle East respiratory syndrome coronavirus (MERS-CoV), rotavirus A (RV-A), hepatitis C virus (HCV), dengue virus (DENV), and hepatitis B virus (HBV). MA-T also inactivated 99.98% of SARS-CoV-2, which is equivalent to ethanol for disinfection. MA-T has proven to be a safe and effective disinfectant. MA-T is a next-generation disinfectant that has the potential to be safer and more effective than conventional chlorine disinfectants and other disinfectants. It also proved to be an effective disinfectant against SARS-CoV-2, which is currently causing pandemic all over the world.
... The mechanism of action of ClO 2 differs depending on the microorganism considered. ClO 2 inactivates a virus by disrupting the viral structure, thereby degrading viral proteins and genomic RNA-DNA, 14,15 destroys the bacterial cytoplasmic membrane resulting in the outflow of intracellular components, 12 and damages the spore's inner membrane, resulting in inactivation of bacterial spores. 16 In yeast, a eukaryotic microbe, ClO 2 causes ion leakage, inhibits the enzymatic activity of metabolic pathways, and alters the cell structure. ...
Article
The microsporidium Nosema bombycis (Nb) causes pebrine, a fatal disease in sericulture. Nb is effectively killed by chlorine dioxide (ClO2); however, the precise killing mechanism remains unclear. We used laser tweezers Raman spectroscopy (LTRS) to monitor the action of ClO2 on individual Nb spores in real time. Raman peaks of ClO2 appeared in Nb spores, corresponding to decreased peaks of trehalose that gradually disappeared. A peak (1658 cm–1) corresponding to the protein α-helix significantly weakened while that (1668 cm–1) corresponding to irregular protein structures was enhanced; their intensities were negatively correlated in a certain time range and dependent on ClO2 concentration. The intensities of peaks at 782 cm–1 (nucleic acids) and 1004 cm–1 (phenylalanine of protein) did not change evidently even under extremely high ClO2 concentrations. Thus, ClO2 rapidly permeates the Nb spore wall, changing the protein secondary structure to lose biological function and destroy permeability, causing trehalose to leak out. These effects are ClO2 concentration-dependent, but no other obvious changes to biomacromolecules were detected. Single-cell analysis using LTRS is an effective method to monitor the action of chemical sporicides on microbes in real time, providing insight into the heterogeneity of cell stress resistance.
... Previous studies have shown that ClO 2 produces its antiviral activity against hepatitis A virus by acting on viral nucleic acids and proteins (19,26). Since ClO 2 has the ability to kill ASFV, we next investigated that whether ClO 2 can damage the nucleic acids of the virus. ...
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African swine fever (ASF) is a highly contagious disease and provokes severe economic losses and health threats. At present no effective vaccine or treatment is available to prevent or cure ASF. Consequently, there is an urgent need to develop effective drugs against ASF virus (ASFV). Chlorine dioxide (ClO2), an ideal biocide, has broad-spectrum antibacterial activity and no drug resistance. Here, we found that ClO2 strongly inhibited ASFV replication in porcine alveolar macrophages (PAMs). The inhibitory effect of ClO2 occurred during viral attachment rather than entry, indicating that ClO2 suppressed the early stage of virus life cycle. ClO2 showed a potent anti-ASFV effect when added either before, simultaneously with, or after virus infection. Furthermore, ClO2 could destroy viral nucleic acids and proteins, which may contribute to its capacity of inactivating ASFV virions. The minimum concentration of degradation of ASFV nucleic acids by ClO2 is 1.2 μg/mL, and the degradation is a temperature-dependent manner. These have guiding significance for ClO2 prevention and control of ASFV infection in pig farms. In addition, ClO2 decreased the expression of ASFV-induced inflammatory cytokines. Overall, our findings suggest that ClO2 may be an ideal candidate for the development of novel anti-ASFV prophylactic and therapeutic drugs in swine industry.
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Pre-harvest contamination of fresh produce and fruits is a possible route for viral transmission which should not be ignored. The contamination originates from viruses shed in human or animal fecal materials which eventually reach crops through many steps and hurdles, including spread of viruses into the agricultural environment through leakage of septic tanks/pipes or runoff from animal lagoons, virus survival during biosolids and manure treatment, virus survival and transport in soil and subsequent contamination of irrigation water, and virus transmission to crops through irrigation water, etc. Initially, large quantities of virus particles may be released from infected humans or animals, and then in the environment viruses are gradually inactivated under various natural conditions (e.g., temperature, water activity, microbial activities, etc.) and only a tiny portion of viruses may reach crops and cause the contamination. However, the fact that the infectious dose of some foodborne viruses is as low as 10–100 particles makes the pre-harvest contamination still a threat to human health. In the USA, the Environmental Protection Agency (USEPA) and United States Department of Agriculture (USDA) regulations and guidances on proper treatment and usage of manure and biosolids for agricultural purpose may largely reduce the release of viruses to the environment; however, pre-harvest viral contamination due to fecal matter is not completely avoidable. This review focuses on the current knowledge of pre-harvest viral contamination and describes the complex transmission process regarding the presence and survival of virus in soil and fecal material, the effect of different biosolids/manure treatment on virus inactivation, the transmission of virus from soil to water, the contamination of crops by irrigation water and survival of virus on crops. KeywordsFoodborne virus-Pre-harvest contamination-Biosolids-Manure-Irrigation
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  Over one-half of foodborne illnesses are believed to be viral in origin. The ability of viruses to persist in the environment and foods, coupled with low infectious doses, allows even a small amount of contamination to cause serious problems. An increased incidence of foodborne illnesses and consumer demand for fresh, convenient, and safe foods have prompted research into alternative food-processing technologies. This review focuses on viral inactivation by both traditional processing technologies such as use of antimicrobial agents and the application of heat, and also novel processing technologies including high-pressure processing, ultraviolet- and gamma-irradiation, and pulsed electric fields. These industrially applicable control measures will be discussed in relation to the 2 most common causes of foodborne viral illnesses, hepatitis A virus and human noroviruses. Other enteric viruses, including adenoviruses, rotaviruses, aichi virus, and laboratory and industrial viral surrogates such as feline caliciviruses, murine noroviruses, bacteriophage MS2 and ΦX174, and virus-like particles are also discussed. The basis of each technology, inactivation efficacy, proposed mechanisms of viral inactivation, factors affecting viral inactivation, and applicability to the food industry with a focus on ready-to-eat foods, produce, and shellfish, are all featured in this review.
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Surface disinfection, as part of environmental hygiene practices, is an efficient barrier to gastroenteritis transmission. However, surface disinfectants may be difficult to obtain in remote, resource-limited, or disaster relief settings. Electrochemical oxidants (ECO) are chlorine-based disinfectants that can be generated using battery power to electrolyze brine (NaCl) solutions. Electrolysis generates a mixed-oxidant solution that contains both chlorine (HOCl, OCl(-)) and reactive oxygen species (e.g., ·OH, O3, H2O2, and ·O2-) capable of inactivating pathogens. One onsite generator of ECO is the Smart Electrochlorinator 200 (SE-200, Cascade Designs, Inc.). In a laboratory study, we assessed ECO surface disinfection efficacy for two gastrointestinal virus surrogates: bacteriophage MS2 and murine norovirus MNV-1. We quantified both infectivity and nucleic acid inactivation using culture-dependent and independent assays. At free available chlorine concentrations of 2,500 ppm and a contact time of 30 s, ECO inactivation of infective MS2 bacteriophage exceeded 7 log10 compared to MNV-1 disinfection of approximately 2 log10. Genomic RNA inactivation was less than infective virus inactivation: MS2 RNA inactivation was approximately 5 log10 compared to MNV-1 RNA inactivation of approximately 1.5 log10. The results are similar to inactivation efficacy of household bleach when used at similar free available chlorine concentrations. Our work demonstrates the potential of ECO solutions, generated onsite, to be used for surface disinfection.
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Oxidative processes are often harnessed as tools for pathogen disinfection. Although the pathways responsible for bacterial inactivation with various biocides are fairly well understood, virus inactivation mechanisms are often contradictory or equivocal. In this study, we provide a quantitative analysis of the total damage incurred by a model virus (bacteriophage MS2) upon inactivation induced by five common virucidal agents (heat, UV, hypochlorous acid, singlet oxygen, and chlorine dioxide). Each treatment targets one or more virus functions to achieve inactivation: UV, singlet oxygen, and hypochlorous acid treatments generally render the genome nonreplicable, whereas chlorine dioxide and heat inhibit host-cell recognition/binding. Using a combination of quantitative analytical tools, we identified unique patterns of molecular level modifications in the virus proteins or genome that lead to the inhibition of these functions and eventually inactivation. UV and chlorine treatments, for example, cause site-specific capsid protein backbone cleavage that inhibits viral genome injection into the host cell. Combined, these results will aid in developing better methods for combating waterborne and foodborne viral pathogens and further our understanding of the adaptive changes viruses undergo in response to natural and anthropogenic stressors.
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Background The purpose of this study was to evaluate the virucidal activity of a new olanexidine-containing formulation for hand hygiene (olanexidine gluconate hand rub; OLG-HR) against non-enveloped viruses and to understand its mechanism of action. Methods The virucidal activities of OLG-HR against two strains of caliciviruses and three adenovirus serotypes were evaluated through suspension tests. Also, virus-like particles were used to predict the effect of olanexidine gluconate on virus particle structure and the rabbit skin irritation test evaluated the skin irritation. Results The results of suspension tests under conditions with and without interfering substances (1.5% BSA) indicated that OLG-HR had a broad-spectrum effect against non-enveloped viruses, and the virucidal effect was unaffected by organic contaminants. Furthermore, olanexidine inhibited the binding ability of virus-like particles to the binding receptor of human norovirus and increased the aggregation of virus-like particles in a dose-dependent manner. Transmission electron microscopy showed that the morphology of the virus-like particles was affected by exposure to olanexidine, indicating that the protein-denaturing effect of olanexidine gluconate caused the loss of receptor-binding capability of the viral capsid protein. Conclusion This study suggests that olanexidine gluconate is a potential biological and environmental disinfectant against norovirus and adenovirus.
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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.
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Chemical disinfection is the most common method used to inactivate viruses from drinking water throughout the world. In this study, cell culture, ELISA, RT-PCR, and spot hybridization were employed to investigate the mechanism underlying chlorine dioxide (ClO(2) )-induced inactivation of Poliovirus type 1 (PV1), which was also confirmed by recombinant viral genome RNA infection models. The results suggested that ClO(2) inactivated PV1 primarily by disrupting the 5'-non-coding region (5'-NCR) of the PV1 genome. Further study revealed that ClO(2) degraded specifically the 40-80 nucleotides (nt) region in the 5'-NCR. Recombinant viral genome RNA infection models confirmed that PV1 RNA lacking this 40-80 nt region was not infectious. This study not only elucidated the mechanism of PV1 inactivation by ClO(2), but also defined the critical genetic target for the disinfectant to inactivate Poliovirus. This study also provides a strategy by which rapid, accurate, and molecular methods based on sensitive genetic targets may be established for evaluating the effects of disinfectants on viruses.
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The antibacterial brushite-forming calcium phospahte cements (CPC) were prepared using an equimolar mixture of β-tricalcium phosphate (β-TCP) and monocalcium phosphate monohydrate (MCPM) with chlorine dioxide (ClO2) generating powders (sodium chlorite and mixed acid activator). The effect of ClO2 on cement setting time, compressive strength, and antibacterial property of novel antibacterial CPC was investigated. The use of 0.3M citric acid solutions as liquid phase enabled final setting times of 5~10 min. The setting time of antibacterial cement systems was prolonged with increasing the amount of antibiotic used. Dry compressive strength was found to be in the range between 9~15 MPa and increased with addition of ClO2 generating powders. Wet compressive strength was slightly decreased compared to dry compressive strength after immersion of cement samples in water for 24 h. The antimicrobial potency of the different cement formulations was investigated using the agar diffusion method. The acidic brushite cement itself showed the inhibitory effect for Streptococcus mutans. The inhibition zone was increased with the amount of ClO2 generating powders. These results indicate that our novel antibacterial CPC have the great potential to avoid the development of infections for preventive antibiotic therapy.
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Epidemics are threatening public health and social development. Emerging as a green disinfectant, H2O2 can prevent the breakout of epidemics in migration. Electrochemical H2O2 production powered by renewable electricity provides a clean and decentralized solution for on‐site disinfection. This review firstly discussed the efficacy of H2O2 in disinfection. Then necessary fundamental principles are summarized to gain insight into electrochemical H2O2 production. The focus is on exploring pathways to realize a highly efficient H2O2 production. Progress in advanced electrocatalysts, typically single‐atom catalysts for the two‐electron oxygen reduction reaction (2e− ORR), are highlighted to provide high H2O2 selectivity design strategies. Finally, a rational design of electrode and electrolytic cells is outlined to realize the on‐site disinfection. Overall, this critical review contributes to exploiting the potentials and constraints of electrochemical H2O2 generation in disinfection and pinpoints future research directions required for implementation.
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Human noroviruses (hNoVs) are the single most common cause of acute non-bacterial gastroenteritis in the industrialized world but cannot be grown in simple culture systems. Different approaches for detecting hNoVs and predicting their infectivity are reviewed. Although reverse transcription quantitative PCR (RT-qPCR) is the most widely used method to detect human noroviruses (hNoVs) it is unable to discriminate between infectious and non-infectious particles. There is therefore a dilemma in assessing the risk to human health from samples detected as positive in RT-qPCR assays. In the absence of an efficient cell, culture based detection system for hNoVs RT-qPCR methods need to differentiate RT-qPCR signals from intact infective particles, intact defective particles, degraded particles (consisting of capsid protein and virus RNA, herein referred to as ribonucleoprotein complexes (RNPs), and "naked" RNA. This review provides a critical analysis of methods for detecting hNoVs, and differentiating such signals with reference to relevant studies of virus infectivity, structure, inactivation, and the disassembly of virus particles during infection. The application of these methods as an adjunct to the proposed RT-qPCR European Committee for Standards (CEN) methods for the detection of hNoVs in foods and the environment is discussed.
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To determine the effectiveness of gaseous chlorine dioxide (gClO2) against a human norovirus surrogate on produce, gClO2 was generated and applied to Tulane virus-coated blueberries in a 240 ml-treatment chamber. gClO2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO2 generated from ≤1 mg acidified sodium chlorite in the small chamber appeared unaffected while gClO2 generated from ≥10 mg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO2 generated from 0.1 mg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330 min. For the 1 mg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15 min exposure and to non-detectable levels (>3.3 logs reductions) after 180 min exposure. Measured concentrations of gClO2 peaked in the treatment chamber at 0.9 μg/l after 10 min for 0.1 mg treatments and 600 μg/l after around 20 min for 1 mg treatment. Overall results indicate that gClO2 could be a feasible waterless intervention for blueberries and other produce.
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أهداف البحث يعتبر فيروس التهاب الكبد البائي من الفيروسات الأكثر انتقالا عن طريق التبرع بالدم والأعضاء، مما ينتج عنه كثيراً من الاعتلالات المرضية والوفيات. فكان من الضروري إجراء اختبارات لكل المتبرعين بالدم والأعضاء للتأكد من خلوهم من الفيروس. والهدف من هذه الدراسة هو توضيح الصورة السيرولوجية لحاملي هذا الفيروس من المتبرعين بالدم والمحولين من المستشفيات الحكومية في المدينة المنورة للتأكد من تعرضهم للفيروس باستخدام تقنية تفاعل البوليميريز المتسلسل. طرق البحث أجريت هذه الدراسة على 17131 عينة أخذت من رجال ونساء (متبرعين للدم تطوعياً ومرضى مشكوك بإصابتهم بالمرض، تم تحويلهم لبنك الدم المركزي في المدينة المنورة – المملكة العربية السعودية). تم الكشف عن الفيروس باستخدام تقنيتين مختلفتين: تقنية تفاعل البوليميريز المتسلسل، وتقنية مقايسة الممتز المناعي المرتبط بالإنزيم. أجريت اختبارات تقنية تفاعل البوليميريز المتسلسل باستخدام معدات (COBAS TagMan V2.0) للكشف عن الحمض النووي للفيروس، واستخدمت ثلاثة اختبارات سيرولوجية مختلفة لاختبار مقايسة الممتز المناعي المرتبط بالإنزيم وهي: المستضد السطحي لإلتهاب الكبد البائي، والأجسام المضادة اللبية لإلتهاب الكبد البائي، والأجسام المضادة السطحية لإلتهاب الكبد البائي. النتائج كانت نسبة ظهور المستضد السطحي لإلتهاب الكبد البائي هي (9.02%)، ونسبة الأجسام المضادة اللبية لإلتهاب الكبد البائي هي (9.02%)، ونسبة الأجسام المضادة السطحية لإلتهاب الكبد البائي هي (7.93%) وكانت نسبة وجود الحمض النووي لفيروس إلتهاب الكبد البائي هي الأعلى وكانت (9.29%). الاستنتاجات عند مقارنة النتائج الايجابية لتقنية تفاعل البوليميريز المتسلسل مع تقنية مقايسة الممتز المناعي المرتبط بالإنزيم، وجد أن تقنية تفاعل البوليميريز المتسلسل هي أكثر دقة وحساسية لكشف الفيروس، كما أن الاختبارات الإيجابية لتقنية مقايسة الممتز المناعي المرتبط بالإنزيم ليست جميعها دقيقة.
Chapter
Foodborne viruses such as noroviruses have become a huge food safety concern, being responsible for more than half of all foodborne illnesses. The high prevalence of foodborne viruses in the food sector may be related to several factors such as their high persistence in the environment and in foods, as well as their low infectious dose. Even if a treatment reduces an initial viral load of 5 log10 by 1000-fold, residual unaffected virions (0.01%) may be sufficient to cause illness. Minimally processed foods such as bivalve molluscs and fresh produce are frequently involved in the transmission of foodborne viruses to humans. This chapter provides an update of the recent findings relating to the inactivation of foodborne viruses using physical and chemical approaches. In addition to traditional methods using heat or chemical compounds such as chlorine and organic acids, innovative technologies such as high-pressure, pulsed light and irradiation as well as ozone or peroxyacid treatments are presented.
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Hepatitis A virus infection is a global public health problem. The virus has a wide range of distribution and it is the main cause of acute hepatitis transmitted by the enteric route in Latin America. The viral particle is stable under environmental conditions and conserves its infectivity for several weeks, enabling its transmission by contaminated water and food. Worldwide, different epidemiological patterns have been identified, which may change over time by modification of social and economic variables in the population such as vaccination and the improvement of hygiene and primary health conditions. This leaves new populations susceptible to infection. In Latin America the circulation of genotype I and subgenotypes A and B has been described, but more research is needed to provide the knowledge needed to manage the prevention and control plans for the worldwide reduction of the prevalence of infection. For this paper, a literature review was performed on the SciELO, PubMed and ScienceDirect databases under the search terms "Hepatitis A", "Epidemiology," "Seroprevalence" and "Infection." From the results obtained, only papers published in English and Spanish to describe epidemiological and molecular studies of interest in Latin America were included.
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The COVID-19 virus has spread rapidly around the world and there are many patients in multiple countries. Great efforts have been made to find effective medications against the COVID-19. This study aims to compare the effectiveness of LINCOCIN® and AZITRO® in the treatment of COVID-19 associated pneumonia. A total of 24 hospitalized patients aged between 30-80 years who were admitted to the Tarsus Medical Park Hospital between February to March 2020 was included in the study. The patients were divided into LINCOCIN® and AZITRO® treatment groups. Bronchoalveolar-lavage PCR results were compared after treatment. The mean age was 58.4±15.4 years in the LINCOCIN® group and 59.1±16.6 years in the AZITRO® group. In the LINCOCIN® group, the rate of males was 66.7% and it was 58.3% in the AZITRO® group. There were no statistical differences in terms of age and gender between the groups. On the 6th day after starting treatment, negative bronchoalveolar PCR result was 83.3% in the LINCOCIN® group and 33.3% in the AZITRO® group. The negative bronchoalveolar PCR proportion was significantly higher in the LINCOCIN® group than in the AZITRO® group. LINCOCIN® usage may be more appropriate in the treatment of COVID-19 associated pneumonia. Further studies with a large sample size should clarify these results.
Chapter
Monitoring the presence of enteric viruses in food is a challenging task, and molecular-based methods have become the reference detection methodology. This chapter describes in detail the main steps of the analytical process of detection of foodborne viruses by molecular methods, paying special attention to key aspects such as the interpretation of test results, the use of controls, and the implication for public health of the results obtained by molecular methods.
In this paper, the inactivation of both free Escherichia coli (FE) and particle-Associated E. coli (PAE) with chlorine dioxide (ClO2) were investigated using granular activated carbon effluent water samples. The inactivation rate of FE was higher than that of PAE and the reactivation ratio of PAE was higher than that of FE, indicating the threat of particle-Associated bacteria. Response surface methodology (RSM) was applied to determine the factors influencing the disinfection efficiency of ClO2 in inactivating PAE. The experimental results indicated that particle concentration was a principal factor influencing the PAE inactivation efficiency, presenting a negative correlation, while exposure time and ClO2 dosage revealed a positive correlation. The inactivation kinetics of PAE using ClO2 was also investigated and the results demonstrated that PAE inactivation with ClO2 fitted the Chick-Watson kinetic model. The inactivation rate constants of PAE were found to follow the Arrhenius expression with an activation energy of 107.5 kJ/mol, indicating a relatively strong temperature dependence. However, there are minor effects of pH and initial ClO2 dosage on PAE inactivation rate constant.
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EPA approved disinfectants for coronavirus lists many products for use on hard, non-porous materials. There are significantly less products registered for use on porous materials. Further, many common, high-touch surfaces fall in between non-porous materials such as glass and porous materials such as soft fabrics. The objective of this study was to assess the efficacy of selected commercially available disinfectant products against coronaviruses on common, high-touch surfaces. Four disinfectants (Clorox Total 360, Bleach solution, Vital Oxide, and Peroxide Multi-Surface Cleaner) were evaluated against Murine Hepatitis Virus A59 (MHV) as a surrogate coronavirus for SARS-CoV-2. MHV in cell culture medium was inoculated onto four materials: stainless steel, latex-painted drywall tape, Styrene Butadiene rubber (rubber), and bus seat fabric. Immediately (T0) or 2-hours (T2) post-inoculation, disinfectants were applied by trigger-pull or electrostatic sprayer and either held for recommended contact times (Spray Only) or immediately wiped (Spray and Wipe). Recovered infectious MHV was quantified by median tissue culture infectious dose assay. Bleach solution, Clorox Total 360, and Vital Oxide were all effective (>3-log10 reduction or complete kill of infectious virus) with both the Spray Only and Spray and Wipe methods on stainless steel, rubber, and painted drywall tape when used at recommended contact times at both T0 and T2 hr. Multi-Surface Cleaner unexpectedly showed limited efficacy against MHV on stainless steel within the recommended contact time; however, it showed increased (2.3 times greater efficacy) when used in the Spray and Wipe method compared to Spray Only. The only products to achieve a 3-log10 reduction on fabric were Vital Oxide and Clorox Total 360; however, efficacy of Vital Oxide against MHV on fabric was reduced to below 3-log10 when applied by electrostatic sprayer compared to trigger-pull sprayer. This study highlights the importance of considering material, product, and application method when developing a disinfection strategy for coronaviruses on high-touch surfaces.
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Background Hepatitis A virus (HAV), a major cause of acute hepatitis, has had the highest occurrence among group 1 nationally notifiable infectious diseases in Korea since 2010.Recently,the annual increase in the HAV infection rate among young adults has become a public health concern. Objectives The aim of this study was to describe an outbreak of acute hepatitis in a residential facility in April 2015 and to identify potential sources of this outbreak. Study design Sera from all exposed residents were tested for anti-HAV IgM or IgG antibodies by ELISA. Clinical (sera and stool) and environmental samples were screened for the presence of HAV RNA using one-step RT-PCR and nested PCR. The VP3-VP1 regions of HAV were analyzed using the BLAST database and MEGA7 software. Results Of the 82 persons in the facility, 12 (14.6%, including 10 residents and 2 health care workers) were diagnosed with hepatitis A. Clinical symptoms were evident in 9 individuals, one of whom died, and the remaining four patients were asymptomatic. Traceback investigation revealed that HAV-RNA (genotype IA) was detected in the patients’ stools and the groundwater used in the facility. Conclusions We described an HAV outbreak in a facility for the disabled due to using a water supply that was mixed with contaminated groundwater. Therefore, HAV vaccination and periodic water inspections in group facilities should be emphasized to prevent HAV infection.
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Virus inactivation validation studies have been widely applied in the risk assessment of biogenic material‐based medical products, such as biological products, animal tissue‐derived biomaterials, and allogeneic biomaterials, to decrease the risk of virus transmission. Traditional virus detection methods in an inactivation validation study utilize cell culture as a tool to quantify the infectious virus by observing cytopathic effects (CPEs) after virus inactivation. However, this is susceptible to subjective factors, because CPEs must be observed by experts under a microscope during virus titration. In addition, this method is costly and time‐ and labor‐consuming. Molecular biological technologies such as quantitative polymerase chain reaction (qPCR) have been widely used for virus detection but cannot distinguish infectious and noninfectious viruses. Therefore, qPCR cannot be directly applied to virus inactivation validation studies. In this paper, methods to detect viruses and progress in the challenge of differentiating infectious and noninfectious viruses with the combination of pretreatment and qPCR techniques such as the integrated cell culture‐qPCR (ICC‐qPCR) method are reviewed. In addition, the advantages and disadvantages of each new method, as well as its prospect in virus inactivation validation studies, are discussed. This article is protected by copyright. All rights reserved.
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Reducing the risk of contamination with foodborne pathogens is paramount in maintaining safety of produce. The raspberry industry uses chlorine spray as a control measure before conveying freshly picked red raspberries into individually quick frozen units. However, the efficacy of sanitizer spray treatment to inactivate norovirus, hepatitis A virus (HAV), and Listeria monocytogenes on raspberries has not been characterized. In this study, a laboratory-scale spray bar device was fabricated to simulate industrial settings. Fresh raspberries were spot inoculated with murine norovirus (MNV, a norovirus surrogate), HAV, or L. monocytogenes and sprayed with 50 ppm of chlorine or 80 ppm of peroxyacetic acid (PAA). Surviving pathogens were enumerated after spray or postspray frozen storage at −20°C for 1 and 24 h. Chlorine and PAA spray treatments reduced MNV and L. monocytogenes from raspberries by 0.2 and 0.6 log but had no effect on HAV. During frozen storage after spray treatment, the residual PAA on the fruit surfaces further reduced MNV and L. monocytogenes, achieving a total reduction of approximately 0.6 and 3.0 log, respectively. HAV levels were not affected by frozen storage after PAA or chlorine spray treatment. The findings were supported by the sanitizer decay results showing that PAA decayed more slowly than active chlorine on raspberry surfaces. Submerging washes conducted as comparisons showed higher reduction of pathogens from raspberry surfaces than similar respective sanitizer spray treatments. The results suggest that PAA could contribute to raspberry postharvest sanitation, aiding in risk reduction of pathogen contamination prior to entering an individually quick frozen unit. HIGHLIGHTS
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Background: Chlorine dioxide (CD) gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control occupationally as well as publicly. However, it remains unknown whether the chronic exposure of CD gas concentration effective against microbes is safe. Therefore, long-term, low concentration CD gas inhalation toxicity was studied in rats as a six-month continuous whole-body exposure followed by a two-week recovery period, so as to prove that the CD gas exposed up to 0.1 ppm (volume ratio) is judged as safe on the basis of a battery of toxicological examinations. Methods: CD gas at 0.05 ppm or 0.1 ppm for 24 hours/day and 7 days/week was exposed to rats for 6 months under an unrestrained condition with free access to chow and water in a chamber so as to simulate the ordinary lifestyle in human. The control animals were exposed to air only. During the study period, the body weight as well as the food and water consumptions were recorded. After the 6-month exposure and the 2-week recovery period, animals were sacrificed and a battery of toxicological examinations, including biochemistry, hematology, necropsy, organ weights and histopathology, were performed. Results: Well regulated levels of CD gas were exposed throughout the chamber over the entire study period. No CD gas-related toxicity sign was observed during the whole study period. No significant difference was observed in body weight gain, food and water consumptions, and relative organ weight. In biochemistry and hematology examinations, changes did not appear to be related to CD gas toxicity. In necropsy and histopathology, no CD gas-related toxicity was observed even in expected target respiratory organs. Conclusions: CD gas up to 0.1 ppm, exceeding the level effective against microbes, exposed to whole body in rats continuously for six months was not toxic, under a condition simulating the conventional lifestyle in human.
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The complete nucleotide sequence of wild-type hepatitis A virus (HAV) HM-175 was determined. The sequence was compared with that of a cell culture-adapted HAV strain (R. Najarian, D. Caput, W. Gee, S.J. Potter, A. Renard, J. Merryweather, G.V. Nest, and D. Dina, Proc. Natl. Acad. Sci. USA 82:2627-2631, 1985). Both strains have a genome length of 7,478 nucleotides followed by a poly(A) tail, and both encode a polyprotein of 2,227 amino acids. Sequence comparison showed 624 nucleotide differences (91.7% identity) but only 34 amino acid differences (98.5% identity). All of the dipeptide cleavage sites mapped in this study were conserved between the two strains. The sequences of these two HAV strains were compared with the partial sequences of three other HAV strains. Most amino acid differences were located in the capsid region, especially in VP1. Whereas changes in amino acids were localized to certain portions of the genome, nucleotide differences occurred randomly throughout the genome. The most extensive nucleotide homology between the strains was in the 5' noncoding region (96% identity for cell culture-adapted strains versus wild type; greater than 99% identity among cell culture-adapted strains). HAV proteins are less homologous with those of any other picornavirus than the latter proteins are when compared with each other. When the sequences of wild-type and cell culture-adapted HAV strains are compared, the nucleotide differences in the 5' noncoding region and the amino acid differences in the capsid region suggest areas that may contain markers for cell culture adaptation and for attenuation.
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Inactivation of poliovirus type 1 by 1 N HCl, 1 N NaOH, 0.5 and 1.0 mg of free chlorine per liter, and UV light was compared by using cell culture and seminested PCR (30 cycles of reverse transcriptase-PCR plus 30 cycles of seminested PCR). A minimum contact time of 45 min with HCl, 3 min with NaOH, 3 and 6 min with 1.0 and 0.5 mg of free chlorine per liter, respectively, was required to render 1.64 x 10(2) PFU of poliovirus type 1 per ml undetectable by seminested PCR. In cell culture, a minimum contact time of 5 min to HCl, 30 s to NaOH, and 1 min to either chlorine concentration was required to render the viruses undetectable by the plaque assay method. No correlation was observed between results by PCR and cell culture when viruses were exposed to UV light. These data suggest that inactivated virus with intact nucleic acid sequences can be detected by PCR.
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Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen. Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts. It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide. This study used both a most-probable-number–cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21°C. The two viability methods produced significantly different results (P < 0.05). Products of disinfectant concentration and contact time (Ct values) of 1,000 mg · min/liter were needed to inactivate approximately 0.5 log10 and 2.0 log10 units (99% inactivation) of C. parvumas measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide.Ct values of 75, 550, and 1,000 mg · min/liter were required to achieve approximately 2.0 log10 units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, includingBacillus subtilis (aerobic) spores andClostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity.
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The study was intended to investigate the feasibility of reverse transcription-PCR (RT-PCR) for evaluation of the efficacy of inactivation of viruses in water and to elucidate the mechanisms of inactivation of hepatitis A virus (HAV) by chlorine. Cell culture, enzyme-linked immunosorbent assay, and long-overlap RT-PCR were used to detect the infectivity, antigenicity, and entire genome of HAV inactivated or destroyed by chlorine. The cell culture results revealed the complete inactivation of infectivity after 30 min of exposure to 10 or 20 mg of chlorine per liter and the highest level of sensitivity in the 5' nontranslated regions (5'NTR), inactivation of which took as much time as the inactivation of infectivity of HAV by chlorine. However, antigenicity was not completely destroyed under these conditions. Some fractions in the coding region were resistant to chlorine. To determine the specific region of the 5'NTR lost, three segments of primers were redesigned to monitor the region from bp 1 to 1023 across the entire genome. It was shown that the sequence from bp 1 to 671 was the region most sensitive to chlorine. The results suggested that the inactivation of HAV by chlorine was due to the loss of the 5'NTR. It is believed that PCR can be used to assess the efficacy of disinfection of HAV by chlorine as well as to research the mechanisms of inactivation of viruses by disinfectants.
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Virucidal effect of UV light on hepatitis A virus was investigated in artificial sea water. Infectious virus was no longer detectable after 15 min irradiation of 3 liter experimentally contaminated water. Genomic amplification by polymerase chain reaction after reverse transcription allowed the detection of viral RNA in all samples even after 60 min irradiation.
Article
The polymerase chain reaction (PCR) is used for the detection of microrganisms in water, but it is known that one does not detect only viable microorganisms by PCR. The following results show the detection of poliovirus on a cell culture assay and by PCR after inactivation by UV irradiation. The virus was irradiated with a low pressure mercury lamp with times up to 4000 seconds (=3980 J/m2). A 4 log inactivation of the virus was complete after 300 seconds (=294 J/m2) as shown by the cell culture assay. The viral RNA was detectable by PCR even at irradiation times of 4000 seconds.
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It has been found that the rate of consumption of hypochlorous acid by the nucleotides cytidine monophosphate (CMP) and adenosine monophosphate (AMP) increases with decreasing pH. At pH 5.6, CMP and AMP are the primary consumers of free chlorine; at pH 7.6 guanosine monophosphate (GMP), as well as CMP and AMP, react readily with hypochlorous acid. At pH 10, the only consumer of hypochlorite is GMP. A parallel was found between the rate of inactivation of virus and the rate of consumption of free chlorine by two of the nucleotides; both the rate of virus inactivation and the rate of consumption of chlorine by AMP and CMP increase with decreasing pH. Under conditions of virus disinfection, uridine monophosphate (UMP) is quite unreactive with aqueous hypochlorous acid.
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The formation of purgeable and nonpurgeable organic chlorine was evaluated as a function of the type and concentration of precursor material, the type and dosage of chlorine, pH, temperature, and ammonia concentration. The concentration of organic chlorine in a public water supply can be minimized by avoiding prechlorination, avoiding higher concentrations of chlorine than are necessary for good disinfection, using combined chlorine rather than free chlorine, maintaining a high pH, and withdrawing water from a source with a low concentration of precursor material and a cool temperature. Because the conditions that favor lower concentrations of organic chlorine are generally the same conditions that tend to reduce the efficiency of disinfection, careful consideration must be given to the adequacy of disinfection if efforts are made to reduce organic chlorine formation.
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Virucidal effect of UV light on hepatitis A virus was investigated in artificial sea water. Infectious virus was no longer detectable after 15 min irradiation of 3 liter experimentally contaminated water. Genomic amplification by polymerase chain reaction after reverse transcription allowed the detection of viral RNA in all samples even after 60 min irradiation.
Article
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Article
Ultra-violet (UV) treatment has been shown to inactivate hepatitis A virus (HAV) in wastewater and polluted drinking water. Whether this method could be used to inactivate virus preparations made for vaccine purposes is not known since the effect of UV on the antigenicity of HAV has not been studied. HAV vaccine preparations have been treated effectively with formaldehyde. However, this method is time-consuming, since treatment times of up to 15 days have been published as necessary for a complete and safe inactivation. We used a cell-culture-derived HAV preparation with a TCID50 of 109 for a UV irradiation experiment. The antigenicity (assessed by a panel of anti-HAV antibodies), viral genome titre (quantitated by polymerase chain reaction) and HAV infectivity were compared after treatment with UV doses of 0, 184, 368, 552, 736 and 920 J m−2. Our results showed the antigenicity of HAV was almost unaltered even when infectious viral particles were no longer detectable. This technique shows potential as a simple and low-cost method for an inactivated HAV vaccine.
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Studies were conducted to evaluate chlorine dioxide reactivity with proteins and the role of these reactions in the inactivation of the bacterial virus f2 with chlorine dioxide. The effect of chlorine dioxide on the ability of f2 to specifically attach to its host Escherichia coli K13 was compared to the inactivation of virus during the initial seconds of contact time. At pH 7.2 and and 5°C, the virus was rapidly inactivated with 0.6 mg l−1 of chlorine dioxide. Approximately 2 log units of inactivation were observed within 30 s. The loss of protein specific attachment function nearly paralleled intact virus inactivation with 1.2 log units of attachment inhibition occurring within 30 s. The inactivation of virus and the inhibition of specific attachment both increased with increasing pH and increasing disinfectant concentration.Inactivation of f2 was hypothesized to occur as the result of chlorine dioxide reacting with discrete chemical moieties in the viral protein. Cysteine, tyrosine and tryptophan reacted with chlorine dioxide within a time frame that could affect viral inactivation. In denatured f2 capsid protein monomers, these amino acids were almost totally degraded within 2 min by chlorine dioxide. Only tyrosine reacted with chlorine dioxide following treatment of the intact virion with disinfectant. Even though the degradation of tyrosine residues occurred at a much slower rate than the rate of virus inactivation, the protein component of f2 virus appeared to be the site of the lethal lesion produced by chlorine dioxide. These tyrosine reactions with chlorine dioxide appeared to alter the virus such that specific attachment was inhibited.
Article
Formation of trihalomethanes (THMs) was investigated in water treated with chlorine dioxide (ClO2) and/or chlorine (Cl2) where humic acid (HA) was used as THMs precursors. When ClO2 was used as the only disinfectant, no THMs were detected in bromide-free water; while only CHBr3 was formed in water containing bromide ion because ClO2 could oxide bromide to form hydrobromous acid which subsequently reacted with HA, and the yield CHBr3 increased with bromide concentration and ClO2 dosing. When water was treated with ClO2 combined with Cl2, only CHCl3 was formed in the absence of bromide, however, all four species of THMs were formed in the presence of bromide; the THMs formation potential decreased gradually with an increase in the ratio of ClO2 to Cl2 because ClO2 reacted with HA to render them unreactive or unavailable for THMs production. When water (with or without bromide ion) was irradiated by light, the yield of THMs was increased as a function of irradiation time to a maximum, and thereafter decreased markedly; the possible mechanism is that irradiation could activate the THMs precursors in HA, and at the same time destroy the reactivity of ClO2 or Cl2. The same results could be collected from natural water treated by ClO2 with or without irradiation.
Article
Studies were conducted with the bacterial virus f2 to determine the reactivity of chlorine dioxide with viral nucleic acid, and to evaluate the role of these reactions in the inactivation of virus with chloride dioxide. The effect of chlorine dioxide on naked infectious RNA was compared to the inactivation of intact virus and to infectious f2 RNA extracted from virus which was treated with chlorine dioxide. At pH 7.2 and 5°C, greater than 4 log units of virus inactivation were observed within 2 min of contact time. Almost no inactivation of infectious RNA extracted from chlorine dioxide treated virus was observed. Treatment of naked infectious RNA with chlorine dioxide yielded less than 1 log unit of inactivation after 5 min of contact time. The rate of inactivation both f2 virus and infectious RNA by chlorine dioxide increased with increasing pH.Inactivation of f2 infectious RNA was attributed to chlorine dioxide reactions with nucleotides. The reaction of chlorine dioxide within yeast RNA was uniquely associated with guanosine monophosphate (GMP). The reaction between chlorine dioxide and GMP may account for inactivation of naked f2 RNA. However, this reaction does not explain the inactivation of intact f2 virus, as the RNA within the treated virion remains infectious despite several log units of virus inactivation.
Article
Thesis (Ph. D.)--University of Cincinnati, 1979. Includes abstract. Bibliography: leaves 210-227.
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Sensitive and specific methods are needed to detect hepatitis A virus (HAV) and other human enteroviruses in environmental samples such as drinking water and foods. Clones of cDNA encoding the 5'-most 1 kb of the HAV and coxsackievirus B3 (CB3) genomes were subcloned into T7/SP6 RNA transcription vectors. In vitro transcribed RNA from the T7 promoter detected their respective HAV or CB3 genomic RNA. Conversely, SP6 transcripts detected viral negative-stranded RNA but not the genome. When both ssRNA probes were tested at high temperature (65 degrees C), they did not hybridize with intracellular RNAs from 6 primate cell cultures used for isolation of HAV and other enteroviruses. The HAV probe did not hybridize with 13 different enteroviruses but detected as little as 500-1000 infectious units of the 7 strains of HAV tested. Conversely, the CB3 probe showed strong homology with all 13 enteroviruses tested but not HAV. The probes were used to detect HAV and other enteroviruses in water samples after virus amplification in cell culture. HAV was detected in water samples obtained during a waterborne hepatitis outbreak using the ssRNA probe. These samples were negative for HAV by direct solid phase radioimmunoassay and were not positive by immunoassays of inoculated cell cultures until several weeks of propagation. The CB3 ssRNA probe detected enteroviruses in samples of surface water and drinking water that were negative for cytopathic effects in inoculated cell cultures.
Article
Poliovirus 1 isolants were recovered from finished drinking water produced by a modern, well-operated water treatment plant. These waters contained free chlorine residuals in excess of 1 mg/liter. The chlorine inactivation of purified high-titer preparations of two such isolants was compared with the inactivation behavior of two stock strains of poliovirus 1, LSc and Mahoney. The surviving fraction of virus derived from the two natural isolants was shown to be orders of magnitude greater than that of the standard strains. These results raise the question whether indirect drinking water standards based on free chlorine residuals are adequate public health measures, or whether direct standards based on virus determinations might be necessary.
Article
Chlorine dioxide, bromine chloride and iodine were compared with chlorine as virucidal agents. Under optimal conditions all disinfectants were effective at low concentrations, but each disinfectant responded differently to acidity and alkalinity. Disinfection by chlorine was impaired by the presence of ammonia, but the other disinfectants retained much of their potency. Disinfection of poliovirus by iodine resulted in structural changes in the virions as seen by electron micrroscopy, but the other disinfectants were able to inactivate poliovirus without causing any apparent structural changes.
Article
Chlorine dioxide and iodine inactivated poliovirus more efficiently at pH 10.0 than at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide and iodine at pH 10.9 showed that viral RNA separated from the capsids, resulting in the conversion of virions from 156S structures to 80S particles. The RNAs release from both chlorine dioxide- and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of poliovirus and changed the pI from pH 7.0 to pH 5.8. However, the mechanisms of inactivation of poliovirus by chlorine dioxide and iodine were found to differ. Iodine inactivated viruses by impairing their ability to adsorb to HeLa cells, whereas chlorine dioxide-inactivated viruses showed a reduced incorporation of [14C]uridine into new viral RNA. We concluded, then, that chlorine dioxide inactivated poliovirus by reacting with the viral RNA and impairing the ability of the viral genome to act as a template for RNA synthesis.
Article
This study examined the effect of chlorine treatment on the infectivity of hepatitis A virus (HAV). Prodromal chimpanzee feces, shown to induce hepatitis in marmosets (Saguinus sp.), was clarified, and the virus was precipitated with 7% polyethylene glycol 6000, harvested, and resuspended. The suspension was layered onto 5 to 30% linear sucrose gradients and centrifuged; the fractions containing HAV were dialyzed, and a 1:500,000 dilution of this preparation induced hepatitis and seroconversion in 2 of 4 marmosets. A 1:50 dilution of this preparation served as inoculum. Untreated inoculum induced overt hepatitis and seroconversion in 100% (5 of 5) of marmosets inoculated intramuscularly. Inoculum treated for various periods (15, 30, or 60 min) with 0.5, 1.0, or 1.5 mg of free residual chlorine per liter induced hepatitis in 14% (2 of 14), 8% (1 of 12), and 10% (1 of 10) of marmosets, respectively, and induced seroconversion in 29, 33, and 10% of the animals. Inoculum treated with 2.0 or 2.5 mg of free residual chlorine per liter was not infectious in marmosets as determined by absence of hepatitis and seroconversion in the 13 animals tested. Thus, treatment levels of 0.5 to 1.5 mg of free residual chlorine per liter inactivated most but not all HAV in the preparation, whereas concentrations of 2.0 and 2.5 mg of free residual chlorine per liter destroyed the infectivity completely. These results suggest that HAV is somewhat more resistant to chlorine than are other enteroviruses.
Article
Recent studies have shown that there is no loss of cell viability when the cells are subjected to ultrasonic standing wave fields in acoustic cell retention systems. These systems are characterised by waves that spatially vary in pressure amplitude in the direction of sound propagation. In this work an anechoic 'one-dimensional' sonication chamber has been developed that produces propagating waves, which differ from standing waves in that the pressure amplitude remains constant as the wave travels in a medium with negligible attenuation. The viability of yeast cell suspensions as a function of treatment time was investigated during exposure to both standing and propagating wave fields with frequencies slightly above 2 MHz. The influence of 12% (vol/vol) of ethanol in water on the spatial arrangement of the cells in suspension was also studied. Changes in yeast cell morphology caused by the different types of suspension media and the ultrasonic treatment were examined by transmission electron microscopy (TEM). The agglomeration of yeast cells within the pressure nodal planes appears to minimise damaging effects due to ultrasonic fields.
Article
MilliQ water was inoculated with poliovirus type 1 strain LSc-1 and was treated with disinfectants, including chlorine, chlorine dioxide, ozone, and UV light. No relationship between probes and plaque assays were seen, demonstrating that viral nucleic acids were not destroyed. These findings suggest that nucleic acid probes cannot distinguish between infectious and noninfectious viruses and cannot be used in the evaluation of treated waters.
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