The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
Vincent R. Hill - One of the best experts on this subject based on the ideXlab platform.
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Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine
Food and Environmental Virology, 2016Co-Authors: Amy M. Kahler, Maureen G. Metcalfe, Charles D. Humphrey, Theresa L Cromeans, Vincent R. HillAbstract:It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce Adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with Human Adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log_10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.
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source water quality effects on monochloramine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Water Research, 2011Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Abstract There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and Human Adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.
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effects of source water quality on chlorine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Applied and Environmental Microbiology, 2010Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Disinfection processes are critical for the reduction of infectious virus concentrations in source water, because viruses are less efficiently removed by primary treatment of drinking water (e.g., coagulation and filtration) than are other pathogen types of concern (e.g., bacteria and protozoa). Over the years, many disinfection studies have focused on the inactivation of viruses in purified and buffered, demand-free, reagent-grade water (RGW). However, relatively few investigators have examined the impact of water quality during the disinfection process, even though water quality has been found to be a significant factor for inactivation of viruses. Several researchers found that the inactivation rate of poliovirus by free chlorine increased as the ionic concentration of water increased. In one study, poliovirus 1 was inactivated three times faster in boric acid buffer than in purified water (3). In addition, several investigators found that when the ionic content of buffered water was raised by the addition of NaCl or KCl, poliovirus 1 was inactivated two to four times faster than in the buffered water alone (2, 16, 17). In another study, poliovirus 1 was inactivated 10 times more rapidly in drinking water than in purified water (4). Studies conducted with natural waters have demonstrated both increased and decreased disinfection efficacy of chlorine in these waters compared to purified or buffered waters. In a study comparing chlorine disinfection in purified water and Potomac estuarine water, coxsackievirus A9 was inactivated more rapidly in the source water. The remaining study viruses (coxsackievirus B1, echovirus 7, Adenovirus 3, poliovirus 1, and reovirus 3) were all inactivated more slowly in the source water (13). Bacteriophage MS2 was inactivated more slowly by free chlorine in two types of surface water than in buffered, demand-free water. However, there was no difference between the inactivation rates of this virus in the buffered water and groundwater (10). In another study, both feline calicivirus and Adenovirus 40 were inactivated more slowly in treated groundwater than in buffered, demand-free water (21). The United States Environmental Protection Agency's (USEPA) Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources (Guidance Manual) recommends disinfectant concentration × contact time (CT) values of 4, 6, and 8 to achieve 2-, 3-, and 4-log10 inactivation, respectively, with chlorine at 5°C and pH 6 to 9 (23). These CT values, which incorporate a safety factor of 3, were obtained from inactivation experiments conducted with monodispersed hepatitis A virus (HAV) in buffered, demand-free water. As water quality can significantly affect the disinfection efficacy of chlorine, it is unclear whether these CT value recommendations are sufficient for inactivation of viruses in source water. More information is needed to systematically examine the role of water quality in chlorine disinfection of viruses. The objective of the present study was to examine the disinfection efficacy of free chlorine on selected viruses from USEPA's Contaminant Candidate List (CCL) (22) in one untreated and two partially treated source waters from distinct geographical regions. By comparing the efficacy of chlorine disinfection in the source water types to disinfection in buffered, chlorine-demand-free RGW (7), the impact of water quality could be examined. The four representative CCL viruses selected for this study included Human Adenovirus 2 (HAdV2), echovirus 1 (E1), coxsackievirus B5 (CVB5), and murine norovirus (MNV), a surrogate for Human norovirus (22). The viruses were selected because they were previously found to be the least effectively inactivated viruses of their type in RGW (6). Disinfection experiments were carried out in duplicate in pH 7 and 8 source water at 5 and 15°C using 0.2 and 1 mg/liter free chlorine. Inactivation curves were plotted using Microsoft Excel, and CT values were calculated using the efficiency factor Hom (EFH) model (9).
Amy M. Kahler - One of the best experts on this subject based on the ideXlab platform.
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Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine
Food and Environmental Virology, 2016Co-Authors: Amy M. Kahler, Maureen G. Metcalfe, Charles D. Humphrey, Theresa L Cromeans, Vincent R. HillAbstract:It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce Adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with Human Adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log_10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.
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source water quality effects on monochloramine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Water Research, 2011Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Abstract There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and Human Adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.
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effects of source water quality on chlorine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Applied and Environmental Microbiology, 2010Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Disinfection processes are critical for the reduction of infectious virus concentrations in source water, because viruses are less efficiently removed by primary treatment of drinking water (e.g., coagulation and filtration) than are other pathogen types of concern (e.g., bacteria and protozoa). Over the years, many disinfection studies have focused on the inactivation of viruses in purified and buffered, demand-free, reagent-grade water (RGW). However, relatively few investigators have examined the impact of water quality during the disinfection process, even though water quality has been found to be a significant factor for inactivation of viruses. Several researchers found that the inactivation rate of poliovirus by free chlorine increased as the ionic concentration of water increased. In one study, poliovirus 1 was inactivated three times faster in boric acid buffer than in purified water (3). In addition, several investigators found that when the ionic content of buffered water was raised by the addition of NaCl or KCl, poliovirus 1 was inactivated two to four times faster than in the buffered water alone (2, 16, 17). In another study, poliovirus 1 was inactivated 10 times more rapidly in drinking water than in purified water (4). Studies conducted with natural waters have demonstrated both increased and decreased disinfection efficacy of chlorine in these waters compared to purified or buffered waters. In a study comparing chlorine disinfection in purified water and Potomac estuarine water, coxsackievirus A9 was inactivated more rapidly in the source water. The remaining study viruses (coxsackievirus B1, echovirus 7, Adenovirus 3, poliovirus 1, and reovirus 3) were all inactivated more slowly in the source water (13). Bacteriophage MS2 was inactivated more slowly by free chlorine in two types of surface water than in buffered, demand-free water. However, there was no difference between the inactivation rates of this virus in the buffered water and groundwater (10). In another study, both feline calicivirus and Adenovirus 40 were inactivated more slowly in treated groundwater than in buffered, demand-free water (21). The United States Environmental Protection Agency's (USEPA) Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources (Guidance Manual) recommends disinfectant concentration × contact time (CT) values of 4, 6, and 8 to achieve 2-, 3-, and 4-log10 inactivation, respectively, with chlorine at 5°C and pH 6 to 9 (23). These CT values, which incorporate a safety factor of 3, were obtained from inactivation experiments conducted with monodispersed hepatitis A virus (HAV) in buffered, demand-free water. As water quality can significantly affect the disinfection efficacy of chlorine, it is unclear whether these CT value recommendations are sufficient for inactivation of viruses in source water. More information is needed to systematically examine the role of water quality in chlorine disinfection of viruses. The objective of the present study was to examine the disinfection efficacy of free chlorine on selected viruses from USEPA's Contaminant Candidate List (CCL) (22) in one untreated and two partially treated source waters from distinct geographical regions. By comparing the efficacy of chlorine disinfection in the source water types to disinfection in buffered, chlorine-demand-free RGW (7), the impact of water quality could be examined. The four representative CCL viruses selected for this study included Human Adenovirus 2 (HAdV2), echovirus 1 (E1), coxsackievirus B5 (CVB5), and murine norovirus (MNV), a surrogate for Human norovirus (22). The viruses were selected because they were previously found to be the least effectively inactivated viruses of their type in RGW (6). Disinfection experiments were carried out in duplicate in pH 7 and 8 source water at 5 and 15°C using 0.2 and 1 mg/liter free chlorine. Inactivation curves were plotted using Microsoft Excel, and CT values were calculated using the efficiency factor Hom (EFH) model (9).
Theresa L Cromeans - One of the best experts on this subject based on the ideXlab platform.
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Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine
Food and Environmental Virology, 2016Co-Authors: Amy M. Kahler, Maureen G. Metcalfe, Charles D. Humphrey, Theresa L Cromeans, Vincent R. HillAbstract:It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce Adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with Human Adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log_10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.
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source water quality effects on monochloramine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Water Research, 2011Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Abstract There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and Human Adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.
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effects of source water quality on chlorine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Applied and Environmental Microbiology, 2010Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Disinfection processes are critical for the reduction of infectious virus concentrations in source water, because viruses are less efficiently removed by primary treatment of drinking water (e.g., coagulation and filtration) than are other pathogen types of concern (e.g., bacteria and protozoa). Over the years, many disinfection studies have focused on the inactivation of viruses in purified and buffered, demand-free, reagent-grade water (RGW). However, relatively few investigators have examined the impact of water quality during the disinfection process, even though water quality has been found to be a significant factor for inactivation of viruses. Several researchers found that the inactivation rate of poliovirus by free chlorine increased as the ionic concentration of water increased. In one study, poliovirus 1 was inactivated three times faster in boric acid buffer than in purified water (3). In addition, several investigators found that when the ionic content of buffered water was raised by the addition of NaCl or KCl, poliovirus 1 was inactivated two to four times faster than in the buffered water alone (2, 16, 17). In another study, poliovirus 1 was inactivated 10 times more rapidly in drinking water than in purified water (4). Studies conducted with natural waters have demonstrated both increased and decreased disinfection efficacy of chlorine in these waters compared to purified or buffered waters. In a study comparing chlorine disinfection in purified water and Potomac estuarine water, coxsackievirus A9 was inactivated more rapidly in the source water. The remaining study viruses (coxsackievirus B1, echovirus 7, Adenovirus 3, poliovirus 1, and reovirus 3) were all inactivated more slowly in the source water (13). Bacteriophage MS2 was inactivated more slowly by free chlorine in two types of surface water than in buffered, demand-free water. However, there was no difference between the inactivation rates of this virus in the buffered water and groundwater (10). In another study, both feline calicivirus and Adenovirus 40 were inactivated more slowly in treated groundwater than in buffered, demand-free water (21). The United States Environmental Protection Agency's (USEPA) Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources (Guidance Manual) recommends disinfectant concentration × contact time (CT) values of 4, 6, and 8 to achieve 2-, 3-, and 4-log10 inactivation, respectively, with chlorine at 5°C and pH 6 to 9 (23). These CT values, which incorporate a safety factor of 3, were obtained from inactivation experiments conducted with monodispersed hepatitis A virus (HAV) in buffered, demand-free water. As water quality can significantly affect the disinfection efficacy of chlorine, it is unclear whether these CT value recommendations are sufficient for inactivation of viruses in source water. More information is needed to systematically examine the role of water quality in chlorine disinfection of viruses. The objective of the present study was to examine the disinfection efficacy of free chlorine on selected viruses from USEPA's Contaminant Candidate List (CCL) (22) in one untreated and two partially treated source waters from distinct geographical regions. By comparing the efficacy of chlorine disinfection in the source water types to disinfection in buffered, chlorine-demand-free RGW (7), the impact of water quality could be examined. The four representative CCL viruses selected for this study included Human Adenovirus 2 (HAdV2), echovirus 1 (E1), coxsackievirus B5 (CVB5), and murine norovirus (MNV), a surrogate for Human norovirus (22). The viruses were selected because they were previously found to be the least effectively inactivated viruses of their type in RGW (6). Disinfection experiments were carried out in duplicate in pH 7 and 8 source water at 5 and 15°C using 0.2 and 1 mg/liter free chlorine. Inactivation curves were plotted using Microsoft Excel, and CT values were calculated using the efficiency factor Hom (EFH) model (9).
David Rodríguez-lázaro - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Effective Inactivation of Enteric Bacteria and Viruses From Swine Effluent and Sludge at Tropical Temperatures
Water Air & Soil Pollution, 2018Co-Authors: Gislaine Fongaro, Marta Hernández, María Cruz García-gonzález, David Rodríguez-lázaro, Airton Kunz, Maria Elisa Magri, Aline Viancelli, Camila Daminelli Schissi, Maria Célia Silva Lanna, Célia Regina Monte BarardiAbstract:The safe recycling of organic wastes such as the nutrients obtained from agriculture activities is a relevant aspect of the “One Health” strategy, a worldwide initiative including all aspects of health care for Humans and animals, as well as aspects related to the conservation and development of the environment. It represents an important opportunity to mitigate the potential impact of microbial pathogens likely present in nutrient natural sources, as digestate, when applied to land as fertilizers. The objectives of the current study were to determine the inactivation of enteric microorganisms in swine digestate (effluent and sludge) during storage in anaerobic conditions and at different ambient temperatures of tropical zones (16, 22, and 37 °C). Human Adenovirus 2 (HAdV-2), bacteriophage PhiX-174, and Salmonella enterica serovar typhimurium ( S. typhimurium ) were used as enteric microbial models to determine the minimum storage time required to reduce at least 3log of enteric microorganisms load in both matrices at the mentioned temperatures. The minimum storage time required for S. typhimurium was shorter than those observed for viruses at 37 °C, while reduction of at least 3log for S. typhimurium was observed after just 1 day; 20 and 90 days were needed for similar reductions for HAdV-2 and PhiX-174, respectively. Similar results were also observed at lower temperatures: 30 and 45 days were needed for S. typhimurium at 22 and 16 °C, respectively, but 30 and 90 days were needed at 22 °C for HAdV-2 PhiX-174, respectively, or 90 and 120 days at 16 °C for HAdV-2 PhiX-174, respectively. This is a pioneering study on the evaluation of inactivation of enteric viruses in swine digestate in usual tropical ambient temperatures; it demonstrates that the time for a considerable inactivation is longer than that observed for a enteric microorganisms ( S. typhimurium ), and shows that the storage of swine digestate at the referred temperatures can be used as a low-cost post-treatment to inactivate enteric microorganisms, allowing a further use as safer fertilizer.
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Propidium Monoazide Integrated with qPCR Enables the Detection and Enumeration of Infectious Enteric RNA and DNA Viruses in Clam and Fermented Sausages
Frontiers in microbiology, 2016Co-Authors: Narciso M. Quijada, Gislaine Fongaro, Célia Regina Monte Barardi, Marta Hernández, David Rodríguez-lázaroAbstract:The increase of foodborne viral outbreaks highlights the need for a rapid and sensitive method for the prediction of viral infectivity in food samples. This study assesses the use of propidium monoazide (PMA) coupled with real-time PCR methods (RT-qPCR or qPCR for RNA or DNA viruses, respectively) in the determination of viral infectivity in complex animal-related food matrices. Clam and Spanish fermented sausage (“chorizo”) samples were spiked with infectious and heat-inactivated Human Adenovirus-2 (HAdV-2) and mengovirus (vMC0). PMA-qPCR/RT-qPCR discriminated infective virus particles, with significant reductions (>2.7 log10 or 99.7%). Additionally, infectious HAdV-2 and vMC0 were quantified by plaque assay (in plaque forming units, PFU), and compared with those in virus genomes copies (GCs) quantified by PMA-qPCR/RT-qPCR. A consistent correlation (R2 > 0.92) was showed between PFU and GCs along serial ten-fold dilutions in both DNA and RNA virus and in both food matrices. This study shows the use of PMA coupled to qPCR/RT-qPCR as a promising alternative for prediction of viral infectivity in food samples in comparison to more expensive and time-consuming methods and for those viruses that are not able to grow under available cell culture techniques.
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Propidium Monoazide Coupled with PCR Predicts Infectivity of Enteric Viruses in Swine Manure and Biofertilized Soil
Food and Environmental Virology, 2016Co-Authors: Gislaine Fongaro, Célia Regina Monte Barardi, Marta Hernández, María Cruz García-gonzález, David Rodríguez-lázaroAbstract:The use of propidium monoazide (PMA) coupled with real-time PCR (RT-qPCR or qPCR for RNA or DNA viruses, respectively) was assessed to discriminate infectious enteric viruses in swine raw manure, swine effluent from anaerobic biodigester (AB) and biofertilized soils. Those samples were spiked either with infectious and heat-inactivated Human Adenovirus-2 (HAdV-2) or mengovirus (vMC_0), and PMA-qPCR/RT-qPCR allowed discriminating inactivated viruses from the infective particles, with significant reductions (>99.9 %). Then, the procedure was further assayed to evaluate the presence and stability of two non-cultivable viruses (porcine Adenovirus and rotavirus A) in natural samples (swine raw manure, swine effluent from AB and biofertilized soils); it demonstrated viral inactivation during the storage period at 23 °C. As a result, the combination of PMA coupled to real-time PCR can be a promising alternative for prediction of viral infectivity in comparison to more labour-intensive and costly techniques such as animal or tissue-culture infectivity methods, and for those viruses that do not have currently available cell culture techniques.
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Evaluation of Extraction Methods for Efficient Detection of Enteric Viruses in Pork Meat Products
Food Analytical Methods, 2011Co-Authors: Mónica Martínez-martínez, Marta Hernández, Marta Diez-valcarce, Nigel Cook, David Rodríguez-lázaroAbstract:We report an in-house protocol for extraction and purification of nucleic acids of enteric viruses, which gives more consistent results than representative commercial methods. The protocol uses 4 M guanidine thiocyanate, 0.5% N -lauroylsarcosine sodium salt, and 25 mM sodium citrate pH 7.0 supplemented with 0.14 M β-mercaptoethanol for lysis of virus particles. The addition of TRIzol followed by chloroform-based separation of the aqueous phase is used to purify nucleic acids from the lysate. RNA precipitation is performed using lithium chloride. This protocol was compared with QIAGEN’s RNeasy Kit and bioMérieux’s NucliSens method, by evaluating the ability of each to detect enteric viruses in a complex food matrix. Three different pork products, i.e., cooked ham, liver, and Spanish fermented sausage (“chorizo”) were artificially contaminated with decreasing numbers of murine norovirus 1 and Human Adenovirus 2. The extracted and purified viral nucleic acids were detected by real-time polymerase chain reaction (PCR) assays. Whereas the two commercial extraction methods did not facilitate robust results (quantification was only possible with some viruses and/or some matrices), when coupled with the in-house protocol the linearity and the efficiency of the quantitative reverse transcription-PCR (qRT-PCR) assays were close to 1 in all the food matrices, independent of the virus. Scalability of the in-house method was evaluated by analysis of 1 and 2.5 g of spiked pig liver samples, and quantification was possible on 1 g samples contaminated with any of the two model viruses. Therefore, the in-house protocol facilitates robust qRT-PCR-based quantitative detection of viruses in pork products, and is moreover relatively cheap and simple to perform.
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Evaluation of Extraction Methods for Efficient Detection of Enteric Viruses in Pork Meat Products
Food Analytical Methods, 2010Co-Authors: Mónica Martínez-martínez, Marta Hernández, Marta Diez-valcarce, Nigel Cook, David Rodríguez-lázaroAbstract:We report an in-house protocol for extraction and purification of nucleic acids of enteric viruses, which gives more consistent results than representative commercial methods. The protocol uses 4 M guanidine thiocyanate, 0.5% N-lauroylsarcosine sodium salt, and 25 mM sodium citrate pH 7.0 supplemented with 0.14 M β-mercaptoethanol for lysis of virus particles. The addition of TRIzol followed by chloroform-based separation of the aqueous phase is used to purify nucleic acids from the lysate. RNA precipitation is performed using lithium chloride. This protocol was compared with QIAGEN’s RNeasy Kit and bioMerieux’s NucliSens method, by evaluating the ability of each to detect enteric viruses in a complex food matrix. Three different pork products, i.e., cooked ham, liver, and Spanish fermented sausage (“chorizo”) were artificially contaminated with decreasing numbers of murine norovirus 1 and Human Adenovirus 2. The extracted and purified viral nucleic acids were detected by real-time polymerase chain reaction (PCR) assays. Whereas the two commercial extraction methods did not facilitate robust results (quantification was only possible with some viruses and/or some matrices), when coupled with the in-house protocol the linearity and the efficiency of the quantitative reverse transcription-PCR (qRT-PCR) assays were close to 1 in all the food matrices, independent of the virus. Scalability of the in-house method was evaluated by analysis of 1 and 2.5 g of spiked pig liver samples, and quantification was possible on 1 g samples contaminated with any of the two model viruses. Therefore, the in-house protocol facilitates robust qRT-PCR-based quantitative detection of viruses in pork products, and is moreover relatively cheap and simple to perform.
Jacquelin M Roberts - One of the best experts on this subject based on the ideXlab platform.
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source water quality effects on monochloramine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Water Research, 2011Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Abstract There is a need for more information regarding monochloramine disinfection efficacy for viruses in water. In this study, monochloramine disinfection efficacy was investigated for coxsackievirus B5 (CVB5), echovirus 11 (E11), murine norovirus (MNV), and Human Adenovirus 2 (HAdV2) in one untreated ground water and two partially treated surface waters. Duplicate disinfection experiments were completed at pH 7 and 8 in source water at concentrations of 1 and 3 mg/L monochloramine at 5 and 15 °C. The Efficiency Factor Hom (EFH) model was used to calculate CT values (mg-min/L) required to achieve 2-, 3-, and 4-log10 reductions in viral titers. In all water types, monochloramine disinfection was most effective for MNV, with 3-log10 CT values at 5 °C ranging from 27 to 110. Monochloramine disinfection was least effective for HAdV2 and E11, depending on water type, with 3-log10 CT values at 5 °C ranging from 1200 to 3300 and 810 to 2300, respectively. Overall, disinfection proceeded faster at 15 °C and pH 7 for all water types. Inactivation of the study viruses was significantly different between water types, but there was no indication that overall disinfection efficacy was enhanced or inhibited in any one water type. CT values for HAdV2 in two types of source water exceeded federal CT value recommendations in the US. The results of this study demonstrate that water quality impacts the inactivation of viruses and should be considered when developing chloramination plans.
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effects of source water quality on chlorine inactivation of Adenovirus coxsackievirus echovirus and murine norovirus
Applied and Environmental Microbiology, 2010Co-Authors: Amy M. Kahler, Theresa L Cromeans, Jacquelin M Roberts, Vincent R. HillAbstract:Disinfection processes are critical for the reduction of infectious virus concentrations in source water, because viruses are less efficiently removed by primary treatment of drinking water (e.g., coagulation and filtration) than are other pathogen types of concern (e.g., bacteria and protozoa). Over the years, many disinfection studies have focused on the inactivation of viruses in purified and buffered, demand-free, reagent-grade water (RGW). However, relatively few investigators have examined the impact of water quality during the disinfection process, even though water quality has been found to be a significant factor for inactivation of viruses. Several researchers found that the inactivation rate of poliovirus by free chlorine increased as the ionic concentration of water increased. In one study, poliovirus 1 was inactivated three times faster in boric acid buffer than in purified water (3). In addition, several investigators found that when the ionic content of buffered water was raised by the addition of NaCl or KCl, poliovirus 1 was inactivated two to four times faster than in the buffered water alone (2, 16, 17). In another study, poliovirus 1 was inactivated 10 times more rapidly in drinking water than in purified water (4). Studies conducted with natural waters have demonstrated both increased and decreased disinfection efficacy of chlorine in these waters compared to purified or buffered waters. In a study comparing chlorine disinfection in purified water and Potomac estuarine water, coxsackievirus A9 was inactivated more rapidly in the source water. The remaining study viruses (coxsackievirus B1, echovirus 7, Adenovirus 3, poliovirus 1, and reovirus 3) were all inactivated more slowly in the source water (13). Bacteriophage MS2 was inactivated more slowly by free chlorine in two types of surface water than in buffered, demand-free water. However, there was no difference between the inactivation rates of this virus in the buffered water and groundwater (10). In another study, both feline calicivirus and Adenovirus 40 were inactivated more slowly in treated groundwater than in buffered, demand-free water (21). The United States Environmental Protection Agency's (USEPA) Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources (Guidance Manual) recommends disinfectant concentration × contact time (CT) values of 4, 6, and 8 to achieve 2-, 3-, and 4-log10 inactivation, respectively, with chlorine at 5°C and pH 6 to 9 (23). These CT values, which incorporate a safety factor of 3, were obtained from inactivation experiments conducted with monodispersed hepatitis A virus (HAV) in buffered, demand-free water. As water quality can significantly affect the disinfection efficacy of chlorine, it is unclear whether these CT value recommendations are sufficient for inactivation of viruses in source water. More information is needed to systematically examine the role of water quality in chlorine disinfection of viruses. The objective of the present study was to examine the disinfection efficacy of free chlorine on selected viruses from USEPA's Contaminant Candidate List (CCL) (22) in one untreated and two partially treated source waters from distinct geographical regions. By comparing the efficacy of chlorine disinfection in the source water types to disinfection in buffered, chlorine-demand-free RGW (7), the impact of water quality could be examined. The four representative CCL viruses selected for this study included Human Adenovirus 2 (HAdV2), echovirus 1 (E1), coxsackievirus B5 (CVB5), and murine norovirus (MNV), a surrogate for Human norovirus (22). The viruses were selected because they were previously found to be the least effectively inactivated viruses of their type in RGW (6). Disinfection experiments were carried out in duplicate in pH 7 and 8 source water at 5 and 15°C using 0.2 and 1 mg/liter free chlorine. Inactivation curves were plotted using Microsoft Excel, and CT values were calculated using the efficiency factor Hom (EFH) model (9).