The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform

Simon Toze - One of the best experts on this subject based on the ideXlab platform.

  • comparative Enteric Viruses and coliphage removal during wastewater treatment processes in a sub tropical environment
    Science of The Total Environment, 2018
    Co-Authors: Andrew Palmer, Leonie Hodgers, J P S Sidhu, Kenton Sena, Simon Toze
    Abstract:

    Microbiological safety of reclaimed water is one of the most important issues in managing potential health risks related to wastewater recycling. Presence and removal of human adenoVirus (HAdV), human polyomaVirus (HPyV), human torque teno Virus (HTtV) and somatic coliphage family Microviridae in three wastewater treatment plants (WWTP) in sub-tropical Brisbane, Australia was investigated. All three WWTPs employ activated sludge process with added on Bardenpho process for nutrient removal. HPyV, HAdV, HTtV and Microviridae were consistently detected in the influent (105 to 106 Genomic copies (GC) L-1) and secondary treated effluent (102 to 103GCL-1). The results of this study suggest that, under appropriate conditions, WWTPs with activated sludge process in sub-tropical climate could be an effective treatment barrier with >3 log10 removal of Enteric Virus. The geometric mean of pooled data for each Virus from all sites showed the highest removal for HPyV (3.65 log10) and lowest for HAdV (2.79 log10) which was statistically significant (p=0.00001). Whereas, the removal rate of HTtV and Microviridae was identical (2.81 log10). A poor correlation between the presence of Enteric Virus in influent or effluent with routinely monitored physicochemical parameters suggests limited use of physicochemical parameters as predictors of Enteric Virus presence. High prevalence of HAdV in influent and effluent combined with comparatively low removal suggest that it could be used as a model microorganism for determining Enteric Virus removal efficacy. Additional tertiary treatment may be required prior to effluent reuse for non-potable purposes or discharge into the recreational waters to prevent exposure of people to health hazards.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

Julie K. Pfeiffer - One of the best experts on this subject based on the ideXlab platform.

  • Microbiota-immune system interactions and Enteric Virus infection.
    Current opinion in virology, 2020
    Co-Authors: Mikal A. Woods Acevedo, Julie K. Pfeiffer
    Abstract:

    Enteric Viruses are important human pathogens that pose a significant global health problem. These Viruses infect the gastrointestinal tract, which contains a community of microbes called the 'microbiota'. We and others have shown that intestinal microbiota are crucial for the replication, pathogenesis, and transmission of a variety of Enteric Viruses. However, the mechanisms underlying microbiota enhancement of Enteric Virus infection remain unclear. Interestingly, the host immune system is dependent on both the abundance and composition of the intestinal microbiota. Here we review several aspects of how microbiota influence the immune system and how this could potentially impact Enteric Virus infection.

  • use of a glycan library reveals a new model for Enteric Virus oligosaccharide binding and virion stabilization
    Unknown Journal, 2019
    Co-Authors: Mark A Lehrman, Julie K. Pfeiffer
    Abstract:

    Enteric Viruses infect the gastrointestinal tract, and bacteria can promote replication and transmission of several Enteric Viruses. Viruses can be inactivated by exposure to heat or bleach, but polioVirus, coxsackieVirus B3, and reoVirus can be stabilized by bacteria or bacterial polysaccharides, limiting inactivation and aiding transmission. We previously demonstrated that certain N-acetylglucosamine (GlcNAc)-containing polysaccharides can stabilize polioVirus. However, the detailed Virus-glycan binding specificity and glycan chain length requirements, and thus the mechanism of virion stabilization, have been unclear. A previous limitation was our lack of defined-length glycans to probe mechanisms and consequences of Virus-glycan interactions. Here, we generated a panel of polysaccharides and oligosaccharides to determine the properties required for binding and stabilization of polioVirus. PolioVirus virions are nonenveloped icosahedral 30-nm particles with 60 copies of each of four capsid proteins, VP1 to VP4. VP1 surrounds the 5-fold axis, and our past work indicates that this region likely contains the glycan binding site. We found that relatively short GlcNAc oligosaccharides, such as a six-unit GlcNAc oligomer, can bind polioVirus but fail to enhance virion stability. Virion stabilization required binding of long GlcNAc polymers of greater than 20 units. Our data suggest a model where GlcNAc polymers of greater than 20 units bind and bridge adjacent 5-fold axes, thus aiding capsid rigidity and stability. This study provides a deeper understanding of Enteric Virus-bacterial glycan interactions, which are important for virion environmental stability and transmission.IMPORTANCE Enteric Viruses are transmitted through the fecal-oral route, but how Enteric Viruses survive in the environment is unclear. Previously, we found that bacterial polysaccharides enhance polioVirus stability against heat or bleach inactivation, but the specific molecular requirements have been unknown. Here, we showed that certain short-chain oligosaccharides can bind to polioVirus but do not increase virion stability. Long-chain polysaccharides bind and may bridge adjacent sites on the viral surface, thus increasing capsid rigidity and stability. This work defines the unique interactions of polioVirus and glycans, which provides insight into virion environmental stability and transmission.

  • related Enteric Viruses have different requirements for host microbiota in mice
    bioRxiv, 2019
    Co-Authors: Christopher M. Robinson, Mikal Woods A Acevedo, Broc T Mccune, Julie K. Pfeiffer
    Abstract:

    Abstract Accumulating evidence suggests that intestinal bacteria promote Enteric Virus infection in mice. For example, previous work demonstrated that antibiotic treatment of mice prior to oral infection with polioVirus reduced viral replication and pathogenesis. Here we examined the effect of antibiotic treatment on infection with coxsackieVirus B3 (CVB3), a picornaVirus closely related to polioVirus. We treated mice with a mixture of five antibiotics to deplete host microbiota and examined CVB3 replication and pathogenesis following oral inoculation. We found that, like polioVirus, CVB3 shedding and pathogenesis were reduced in antibiotic-treated mice. While treatment with just two antibiotics, vancomycin and ampicillin, was sufficient to reduce CVB3 replication and pathogenesis, this treatment had no effect on polioVirus. Quantity and composition of bacterial communities were altered by treatment with the five antibiotic cocktail and by treatment with vancomycin and ampicillin. To determine whether more subtle changes in bacterial populations impact viral replication, we examined viral infection in mice treated with milder antibiotic regimens. Mice treated with one-tenth the concentration of the normal antibiotic cocktail supported replication of polioVirus but not CVB3. Importantly, a single dose of one antibiotic, streptomycin, was sufficient to reduce CVB3 shedding and pathogenesis, while having no effect on polioVirus shedding and pathogenesis. Overall, replication and pathogenesis of CVB3 is more sensitive to antibiotic treatment than polioVirus, indicating that closely related Viruses may differ in their reliance on microbiota. Importance Recent data indicate that intestinal bacteria promote intestinal infection of several Enteric Viruses. Here we show that coxsackieVirus, an Enteric Virus in the picornaVirus family, also relies on microbiota for intestinal replication and pathogenesis. Relatively minor depletion of the microbiota was sufficient to decrease coxsackieVirus infection, while polioVirus infection was unaffected. Surprisingly, a single dose of one antibiotic was sufficient to reduce coxsackieVirus infection. Therefore, these data indicate that microbiota can influence Enteric Virus infection through distinct mechanisms, even for closely related Viruses.

  • bacteria facilitate Enteric Virus co infection of mammalian cells and promote genetic recombination
    Cell Host & Microbe, 2018
    Co-Authors: Andrea K Erickson, Palmy R Jesudhasan, Melinda J Mayer, Arjan Narbad, Sebastian E Winter, Julie K. Pfeiffer
    Abstract:

    Summary RNA Viruses exist in genetically diverse populations due to high levels of mutations, many of which reduce viral fitness. Interestingly, intestinal bacteria can promote infection of several mammalian Enteric RNA Viruses, but the mechanisms and consequences are unclear. We screened a panel of 41 bacterial strains as a platform to determine how different bacteria impact infection of polioVirus, a model Enteric Virus. Most bacterial strains, including those extracted from cecal contents of mice, bound polioVirus, with each bacterium binding multiple virions. Certain bacterial strains increased viral co-infection of mammalian cells even at a low Virus-to-host cell ratio. Bacteria-mediated viral co-infection correlated with bacterial adherence to cells. Importantly, bacterial strains that induced viral co-infection facilitated genetic recombination between two different Viruses, thereby removing deleterious mutations and restoring viral fitness. Thus, bacteria-Virus interactions may increase viral fitness through viral recombination at initial sites of infection, potentially limiting abortive infections.

  • sex dependent intestinal replication of an Enteric Virus
    Journal of Virology, 2017
    Co-Authors: Christopher M. Robinson, Yao Wang, Julie K. Pfeiffer
    Abstract:

    ABSTRACT CoxsackieVirus is an Enteric Virus that initiates infection in the gastrointestinal tract before disseminating to peripheral tissues to cause disease, but intestinal factors that influence viral replication are understudied. Furthermore, a sex bias for severe sequelae from coxsackieVirus infections has been observed in humans. While mouse models mimicking human pathogenesis have been well characterized, many of these experiments use intraperitoneal injection of coxsackieVirus to infect mice, bypassing the intestine. In light of recent studies identifying intestinal factors, such as the microbiota, that alter Enteric viral replication, we sought to investigate coxsackieVirus replication within the intestine. Here, we orally infected mice with coxsackieVirus B3 (CVB3) and found that CVB3 replication in the intestine is sex dependent. CVB3 replicated efficiently in the intestine of male mice but not female mice. Additionally, we found that the type I interferon response and sex hormones can alter both viral replication and lethality. Overall, these data suggest that sex and the immune response play a vital role in CVB3 replication in the intestine and should be considered in light of the sex bias observed in human disease. IMPORTANCE Sex bias in severe sequelae from Enteric viral infections has been observed. Since Viruses have evolved to achieve optimal levels of fitness in their environmental niches, it is imperative to study Viruses at the site of initial replication. Here, we used an oral inoculation system for CVB3, which follows the natural route of infection in the gastrointestinal tract. We found that sex can influence the replication of CVB3 in the intestine. Additionally, the type I interferon response and sex hormones alter both CVB3 intestinal replication and lethality. Overall this work highlights the fact that sex should be considered in investigations of Enteric viral replication and pathogenesis.

Leonie Hodgers - One of the best experts on this subject based on the ideXlab platform.

  • comparative Enteric Viruses and coliphage removal during wastewater treatment processes in a sub tropical environment
    Science of The Total Environment, 2018
    Co-Authors: Andrew Palmer, Leonie Hodgers, J P S Sidhu, Kenton Sena, Simon Toze
    Abstract:

    Microbiological safety of reclaimed water is one of the most important issues in managing potential health risks related to wastewater recycling. Presence and removal of human adenoVirus (HAdV), human polyomaVirus (HPyV), human torque teno Virus (HTtV) and somatic coliphage family Microviridae in three wastewater treatment plants (WWTP) in sub-tropical Brisbane, Australia was investigated. All three WWTPs employ activated sludge process with added on Bardenpho process for nutrient removal. HPyV, HAdV, HTtV and Microviridae were consistently detected in the influent (105 to 106 Genomic copies (GC) L-1) and secondary treated effluent (102 to 103GCL-1). The results of this study suggest that, under appropriate conditions, WWTPs with activated sludge process in sub-tropical climate could be an effective treatment barrier with >3 log10 removal of Enteric Virus. The geometric mean of pooled data for each Virus from all sites showed the highest removal for HPyV (3.65 log10) and lowest for HAdV (2.79 log10) which was statistically significant (p=0.00001). Whereas, the removal rate of HTtV and Microviridae was identical (2.81 log10). A poor correlation between the presence of Enteric Virus in influent or effluent with routinely monitored physicochemical parameters suggests limited use of physicochemical parameters as predictors of Enteric Virus presence. High prevalence of HAdV in influent and effluent combined with comparatively low removal suggest that it could be used as a model microorganism for determining Enteric Virus removal efficacy. Additional tertiary treatment may be required prior to effluent reuse for non-potable purposes or discharge into the recreational waters to prevent exposure of people to health hazards.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

Andrew Palmer - One of the best experts on this subject based on the ideXlab platform.

  • comparative Enteric Viruses and coliphage removal during wastewater treatment processes in a sub tropical environment
    Science of The Total Environment, 2018
    Co-Authors: Andrew Palmer, Leonie Hodgers, J P S Sidhu, Kenton Sena, Simon Toze
    Abstract:

    Microbiological safety of reclaimed water is one of the most important issues in managing potential health risks related to wastewater recycling. Presence and removal of human adenoVirus (HAdV), human polyomaVirus (HPyV), human torque teno Virus (HTtV) and somatic coliphage family Microviridae in three wastewater treatment plants (WWTP) in sub-tropical Brisbane, Australia was investigated. All three WWTPs employ activated sludge process with added on Bardenpho process for nutrient removal. HPyV, HAdV, HTtV and Microviridae were consistently detected in the influent (105 to 106 Genomic copies (GC) L-1) and secondary treated effluent (102 to 103GCL-1). The results of this study suggest that, under appropriate conditions, WWTPs with activated sludge process in sub-tropical climate could be an effective treatment barrier with >3 log10 removal of Enteric Virus. The geometric mean of pooled data for each Virus from all sites showed the highest removal for HPyV (3.65 log10) and lowest for HAdV (2.79 log10) which was statistically significant (p=0.00001). Whereas, the removal rate of HTtV and Microviridae was identical (2.81 log10). A poor correlation between the presence of Enteric Virus in influent or effluent with routinely monitored physicochemical parameters suggests limited use of physicochemical parameters as predictors of Enteric Virus presence. High prevalence of HAdV in influent and effluent combined with comparatively low removal suggest that it could be used as a model microorganism for determining Enteric Virus removal efficacy. Additional tertiary treatment may be required prior to effluent reuse for non-potable purposes or discharge into the recreational waters to prevent exposure of people to health hazards.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

  • Optimization of sampling strategy to determine pathogen removal efficacy of activated sludge treatment plant
    Environmental Science and Pollution Research, 2017
    Co-Authors: Jatinder P. S. Sidhu, Kylie Smith, Leonie Hodgers, Andrew Palmer, Warish Ahmed, Simon Toze
    Abstract:

    Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenoVirus (HAdV) and polyomaVirus (HPyV) by up to 3 log_10. The Virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log_10) and very poor correlation with the Enteric Virus, it is not recommended that E. coli be used as a surrogate for Enteric Virus removal. The results also demonstrated no statistically significant differences ( t test, P  > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of Virus. In order to cover for the potential seasonal prevalence of Viruses such as noroVirus and rotaVirus, sampling should be spread across all seasons.

Nicholas J. Ashbolt - One of the best experts on this subject based on the ideXlab platform.

  • interactions between human reoVirus and free living amoebae implications for Enteric Virus disinfection and aquatic persistence
    Environmental Science & Technology, 2020
    Co-Authors: Melanie A Folkins, Nicholas J. Ashbolt, Rafik Dey
    Abstract:

    Free-living amoebae (FLA) are ubiquitous protozoa in aquatic/soil habitats and known to resist various disinfection methods commonly used in drinking and wastewater treatment plants. ReoViruses are emerging as useful infectious Enteric Virus indicators of wastewater treatment efficacy. The possible enhanced protection FLA may provide reoViruses, however, has not been previously described. Using an infectious clinical reoVirus isolate in coculture with three FLA, namely, Vermamoeba vermiformis, Acanthamoeba polyphaga, and Willaertia magna, we followed reoVirus persistence (by quantitative reverse transcription polymerase chain reaction (RT-qPCR)) and infectivity (TCID50). Virions present in samples persisted over the experimental time period, with most virions remaining infectious. Surprisingly, electron microscopy revealed virions accumulated within the nucleus of amoebae. The current work appears to be the first report of reoVirus being internalized within FLA and remaining infectious, providing a previously unreported environmental reservoir and potential mode of dissemination. FLA also appeared to be providing some logs in protection to internalized Viruses during UV irradiation, which if not accounted for when determining UV dosage needed for sufficient disinfection may result in unintentional release of pathogens into surrounding water systems.

  • spiked Virus level needed to correctly assess Enteric Virus recovery in water matrices
    Applied and Environmental Microbiology, 2019
    Co-Authors: Yuanyuan Qiu, Xiao L Pang, Nicholas J. Ashbolt
    Abstract:

    Quantitative microbial risk assessment (QMRA) identifies human Enteric Viruses in municipal wastewater as the pathogen group requiring the highest log reductions for various reuse applications. However, the performance of methods for estimating Virus concentration is not well understood, and without performance assessment, actual risks are likely severely underestimated. To evaluate the efficiency of Virus recovery from water, a water sample is often spiked with "known" amounts of Virus, and the Virus is then recovered after a series of analytical procedures. Yet for water matrices such as wastewater, due to the unknown background concentrations of targeted Viruses in the matrix and the variable recovery efficiency between individual processes, only an approximation of the recovery efficiency may be obtained from such spike-and-recovery experiments. In this study, we demonstrated theoretically that for two widely used approximations, the error in estimating Virus recovery should be less than the ratio of the amount of target Virus in the background sample to that in the spike. Furthermore, we developed an applicable method, based on this new understanding, for deciding on the amount of Virus for spiking before conducting a spike-and-recovery experiment, so that the approximation error is restricted to an acceptable level for each individual process. Finally, we applied the method to a set of experimental data for Viruses in wastewater, demonstrating its utility and noting its general applicability to other pathogens or water matrices.IMPORTANCE The performance of procedures for pathogen log reduction is at the heart of new risk-based guidance/regulation globally, yet the methods for undertaking assessments of pathogen recovery are not standardized despite their fundamental impacts on assessing log reductions. Here we describe the level of spiking agent(s) that is necessary to correctly assess spiked pathogen/surrogate recovery with whatever method is deployed. The significance of our research lies in identifying the importance of the amount of spiking agents for reducing uncertainty in recovery estimates, which will allow the development of a recommendation for spiking experiments, proactively applying this understanding.

  • Bacteriophages as indicators of faecal pollution and Enteric Virus removal.
    Letters in applied microbiology, 2017
    Co-Authors: Brian R. Mcminn, Nicholas J. Ashbolt, Asja Korajkic
    Abstract:

    Bacteriophages are an attractive alternative to faecal indicator bacteria (FIB), particularly as surrogates of Enteric Virus fate and transport, due to their closer morphological and biological properties. Based on a review of published data, we summarize densities of coliphages (F+ and somatic), Bacteroides spp. and enterococci bacteriophages (phages) in individual human waste, raw wastewater, ambient fresh and marine waters and removal through wastewater treatment processes utilizing traditional treatments. We also provide comparisons with FIB and Enteric Viruses whenever possible. Lastly, we examine fate and transport characteristics in the aquatic environment and provide an overview of the environmental factors affecting their survival. In summary, concentrations of bacteriophages in various sources were consistently lower than FIB, but more reflective of infectious Enteric Virus levels. Overall, our investigation indicates that bacteriophages may be adequate viral surrogates, especially in built systems, such as wastewater treatment plants. Significance and Impact of the Study Bacteriophage are alternative fecal indicators that may be better surrogates for viral pathogens than fecal indicator bacteria (FIB). This report offers a summary of the existing literature concerning the utility of bacteriophage as indicators of viral presence (fecal sources and surface waters) and persistence (in built infrastructure and aquatic environments). Our findings indicate that bacteriophage levels in all matrices examined are consistently lower than FIB, but similar to viral pathogens. Furthermore, in built infrastructure (e.g. wastewater treatment systems) bacteriophage closely mimic viral pathogen persistence suggesting they may be adequate sentinels of Enteric Virus removal.

  • role of hydrophobic and electrostatic interactions for initial Enteric Virus retention by mf membranes
    Journal of Membrane Science, 2001
    Co-Authors: E M Van Voorthuizen, Nicholas J. Ashbolt, Andrea I Schafer
    Abstract:

    Abstract Membranes are of increasing interest for the removal of human Enteric Viruses from wastewater, especially when the goal of treatment is reuse. Limited work has been undertaken on fundamental issues such as aggregation and the role of electrostatic and hydrophobic interactions, as opposed to the sieving of Viruses by membranes. One apparently critical factor would be the iso-electric point (pI) of a Virus. As an example of a worst-case model Virus, the retention of bacteriophage MS-2 was investigated using hydrophobic (GVHP) and hydrophilic (GVWP) 0.22 μm MF membranes at different pH levels and with different salts. High retention levels were measured at the iso-electric point of MS-2, pH 3.9 (5 log retention) and pH 7 (4.3 log retention) in the presence of salts and with a hydrophobic membrane. When retention was compared on a hydrophilic membrane, it was clear that hydrophobic interactions dominated Virus retention, and this was improved by salt, presumably causing reduction of the Gouy double-layer when MS-2 was charged (pH 7). This paper shows that knowledge of the adsorption characteristics of Viruses and the suspending conditions are important to predict removal of Viruses by hydrophobic MF membranes, and discusses some of the practical implications of these important hydrophobic interactions.