The Experts below are selected from a list of 10263 Experts worldwide ranked by ideXlab platform
Akihiko Hata - One of the best experts on this subject based on the ideXlab platform.
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Quantitative Distribution of Infectious F-Specific RNA Phage Genotypes in Surface Waters.
Applied and environmental microbiology, 2016Co-Authors: Akihiko Hata, Seiya Hanamoto, Yuya Shirasaka, Naoyuki Yamashita, Hiroaki TanakaAbstract:ABSTRACT F-specific RNA Phages (FRNAPHs) are considered potential viral indicators of water pollution due to their occurrence and stability in water environments. However, their suitability as viral indicators is not fully elucidated because the characteristics of FRNAPHs are variable depending on the genotype. In this study, for the characterization of infectious FRNAPH genotypes, integrated culture reverse transcription-PCR coupled with the most probable number approach was applied to surface water samples. Further, to recover low concentrations of FRNAPH genotypes, an FRNAPH recovery method was developed. The novel FRNAPH recovery method using a noncharged microfiltration membrane could effectively recover FRNAPH strains without inactivation, while a method using an electronegative microfiltration membrane resulted in the inactivation of some strains. Infectious FRNAPH genotypes in surface water samples were successfully quantified with an efficiency comparable to that of the conventional plaque assay. Genotype I (GI) and GII FRNAPHs tended to be predominant at locations impacted by treated and untreated municipal wastewater, respectively. The numbers and proportions of infectious FRNAPHs tended to be higher during the winter season when water temperature decreased. IMPORTANCE Properties of FRNAPHs are highly variable depending on their genotypes. Previous typing methods for FRNAPHs are not quantitative and/or are based on molecular assays, which cannot differentiate infective strains from inactive strains. Due to the reasons mentioned above, the utility of FRNAPHs as viral indicators of water pollution has not been fully validated. In this study, a quantitative genotyping method for infectious FRNAPHs was developed and applied to surface water samples. The method enabled characterization of infectious FRNAPH genotypes in terms of their occurrence and seasonality. Moreover, comparison of the method to a conventional molecular assay (reverse transcription-quantitative PCR) enabled characterization of their stability. Our approach can provide novel findings for further validation of FRNAPHs as viral indicators of water pollution.
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occurrence and reduction of human viruses f specific RNA coliPhage genogroups and microbial indicators at a full scale wastewater treatment plant in japan
Journal of Applied Microbiology, 2013Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
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Occurrence and reduction of human viruses, F‐specific RNA coliPhage genogroups and microbial indicators at a full‐scale wastewater treatment plant in Japan
Journal of applied microbiology, 2012Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
Hiroyuki Katayama - One of the best experts on this subject based on the ideXlab platform.
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occurrence and reduction of human viruses f specific RNA coliPhage genogroups and microbial indicators at a full scale wastewater treatment plant in japan
Journal of Applied Microbiology, 2013Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
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Occurrence and reduction of human viruses, F‐specific RNA coliPhage genogroups and microbial indicators at a full‐scale wastewater treatment plant in Japan
Journal of applied microbiology, 2012Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
Masaaki Kitajima - One of the best experts on this subject based on the ideXlab platform.
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occurrence and reduction of human viruses f specific RNA coliPhage genogroups and microbial indicators at a full scale wastewater treatment plant in japan
Journal of Applied Microbiology, 2013Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
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Occurrence and reduction of human viruses, F‐specific RNA coliPhage genogroups and microbial indicators at a full‐scale wastewater treatment plant in Japan
Journal of applied microbiology, 2012Co-Authors: Akihiko Hata, Masaaki Kitajima, Hiroyuki KatayamaAbstract:Aims To evaluate and compare the reductions of human viruses and F-specific coliPhages in a full-scale wastewater treatment plant based on the quantitative PCR (qPCR) and plate count assays. Methods and Results A total of 24 water samples were collected from four locations at the plant, and the relative abundance of human viruses and F-RNA Phage genogroups were determined by qPCR. Of the 10 types of viruses tested, enteric adenoviruses were the most prevalent in both influent and effluent wastewater samples. Of the different treatment steps, the activated sludge process was most effective in reducing the microbial loads. Viruses and F-RNA Phages showed variable reduction; among them, GI and GIII F-RNA Phages showed the lowest and the highest reduction, respectively. Conclusions Ten types of viruses were present in wastewater that is discharged into public water bodies after treatment. The variability in reduction for the different virus types demonstrates that selection of adequate viral indicators is important for evaluating the efficacy of wastewater treatment and ensuring the water safety. Significance and Impact of the Study Our comprehensive analyses of the occurrence and reduction of viruses and indicators can contribute to the future establishment of appropriate viral indicators to evaluate the efficacy of wastewater treatment.
Christophe Gantzer - One of the best experts on this subject based on the ideXlab platform.
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Occurrence and persistence of enteroviruses, noroviruses and F-specific RNA Phages in natural wastewater biofilms
Water Research, 2009Co-Authors: Sylvain Skraber, Leslie Ogorzaly, Karim Helmi, Armand Maul, Lucien Hoffmann, Henry-michel Cauchie, Christophe GantzerAbstract:Enteroviruses and noroviruses are pathogenic viruses excreted by infected individuals. Discharged in wastewaters, some of these viruses can be captured by biofilms. In the present study, we assessed the occurrence and persistence of these viruses in wastewaters and in corresponding biofilms. Natural wastewaters and biofilms were analyzed monthly from January to July using real-time RT-PCR. Enterovirus RNA was detected in wastewater in June while norovirus RNA was detected from January to March. In contrast, biofilm analysis revealed the presence of both enterovirus and norovirus genomes throughout the study period. For instance, enterovirus and norovirus genogroups (GG) I and II were detected in 50, 46 and 37% of the biofilm samples, respectively (n = 24). In a laboratory experiment, persistence of norovirus GGI RNA (quantified using molecular techniques) and F-specific bacterioPhages (quantified using both culture and molecular techniques) was assessed in wastewater and corresponding naturally-contaminated biofilms at both 4 and 20 °C. The concentrations of viral genomes (norovirus GGI and F-specific RNA Phage) were very stable in biofilms. Indeed, no significant decrease was observed during the persistence experiment that lasted 49 days. Furthermore, regardless of our experimental conditions, viral genome and infectious F-specific bacterioPhages persisted longer in biofilm than in wastewater. According to our results, wastewater biofilms may contribute to the persistence and dispersal of pathogenic viruses outside of epidemic periods.
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relationship between f specific RNA Phage genogroups faecal pollution indicators and human adenoviruses in river water
Water Research, 2009Co-Authors: Leslie Ogorzaly, Adeline Tissier, Isabelle Bertrand, A Maul, Christophe GantzerAbstract:Recent studies have shown the increasing interest of F-specific RNA Phage genotyping to identify major sources of faecal contamination in waters. This study, conducted in a river located in an urbanized watershed with recognized anthropogenic influences, was aimed at evaluating the relevance of direct Phage genotyping by real-time RT-PCR. One hundred percent of positive results were obtained with a 5 mL aliquot of river water (n=31). Phage distribution was modified after cultivation, since the ratio of the two most abundant genogroups (II and I) reached 1.51 log(10) by direct RT-PCR-based method versus 0.30 log(10) after cultivation (n=8). For the first time, positive correlations between the concentrations of genogroup II, bacterial indicators and human adenoviruses were observed, which may indicate a human faecal pollution. No correlation between genogroups II and I has been revealed. The concentration of genogroup I was only correlated with water turbidity, suggesting an animal pollution coming from upstream after rainfall events. Among the microbiological parameters studied, only genogroup II/genogroup I ratio shows variations occurring in the major sources of faecal pollution.
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Development of real-time RT-PCR methods for specific detection of F-specific RNA bacterioPhage genogroups: Application to urban raw wastewater
Journal of Virological Methods, 2006Co-Authors: Leslie Ogorzaly, Christophe GantzerAbstract:F-specific RNA bacterioPhages have been classified into four genogroups (GI, GII, GIII and GIV). It was suggested that two of these genogroups are more frequent in human excreta (GII and GIII) and the two other (GI and GIV) are specific for animal excreta. Real-time RT-PCR methods using TaqMan MGB probe were developed to detect the four genogroups. Primers and probes of each specific RT-PCR were designed to target all sequenced bacterioPhages belonging to one genogroup, without cross-reactivity with other genogroups. These four methods showed detection limits ranging between 0.01 and 10 PFU/mL and PCR efficiencies ranging between 87 and 95%. The newly methods were tested in urban raw wastewater. Genogroups I and II were detected in all samples (n = 7); GIII in six samples and GIV was never detected. GI was predominant in one sample, in which the quantity of Cryptosporidium and Giardia was, respectively, three and eight times higher than the mean values. Because GI is mainly observed in animals, it was hypothesized that this increase was due to an animal input. The use of F-specific RNA Phage genotyping to estimate the origin of faecal pollution requires appropriate validation. In this context, real-time RT-PCR will undoubtedly be useful.
Hans Weber - One of the best experts on this subject based on the ideXlab platform.
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Altered 3'-terminal RNA structure in Phage Qbeta adapted to host factor-less Escherichia coli.
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Daniel Schuppli, Giovanni Miranda, Ho-ching Tiffany Tsui, Malcolm E Winkler, José M. Sogo, Hans WeberAbstract:The RNA Phage Qβ requires for the replication of its genome an RNA binding protein called Qβ host factor or Hfq protein. Our previous results suggested that this protein mediates the access of replicase to the 3′-end of the Qβ plus strand RNA. Here we report the results of an evolutionary experiment in which Phage Qβ was adapted to an Escherichia coli Q13 host strain with an inactivated host factor (hfq) gene. This strain initially produced Phage at a titer ≈10,000-fold lower than the wild-type strain and with minute plaque morphology, but after 12 growth cycles, Phage titer and plaque size had evolved to levels near those of the wild-type host. RNAs isolated from adapted Qβ mutants were efficient templates for replicase without host factor in vitro. Electron microscopy showed that mutant RNAs, in contrast to wild-type RNA, efficiently interacted with replicase at the 3′-end in the absence of host factor. The same set of four mutations in the 3′-terminal third of the genome was found in several independently evolved Phage clones. One mutation disrupts the base pairing of the 3′-terminal CCCoh sequence, suggesting that the host factor stimulates activity of the wild-type RNA template by melting out its 3′-end.
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Altered 3′-terminal RNA structure in Phage Qβ adapted to host factor-less Escherichia coli
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Daniel Schuppli, Giovanni Miranda, Ho-ching Tiffany Tsui, Malcolm E Winkler, José M. Sogo, Hans WeberAbstract:The RNA Phage Qβ requires for the replication of its genome an RNA binding protein called Qβ host factor or Hfq protein. Our previous results suggested that this protein mediates the access of replicase to the 3′-end of the Qβ plus strand RNA. Here we report the results of an evolutionary experiment in which Phage Qβ was adapted to an Escherichia coli Q13 host strain with an inactivated host factor (hfq) gene. This strain initially produced Phage at a titer ≈10,000-fold lower than the wild-type strain and with minute plaque morphology, but after 12 growth cycles, Phage titer and plaque size had evolved to levels near those of the wild-type host. RNAs isolated from adapted Qβ mutants were efficient templates for replicase without host factor in vitro. Electron microscopy showed that mutant RNAs, in contrast to wild-type RNA, efficiently interacted with replicase at the 3′-end in the absence of host factor. The same set of four mutations in the 3′-terminal third of the genome was found in several independently evolved Phage clones. One mutation disrupts the base pairing of the 3′-terminal CCCoh sequence, suggesting that the host factor stimulates activity of the wild-type RNA template by melting out its 3′-end.
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altered 3 terminal RNA structure in Phage qβ adapted to host factor less escherichia coli
Proceedings of the National Academy of Sciences of the United States of America, 1997Co-Authors: Daniel Schuppli, Giovanni Miranda, Ho-ching Tiffany Tsui, Malcolm E Winkler, José M. Sogo, Hans WeberAbstract:The RNA Phage Qβ requires for the replication of its genome an RNA binding protein called Qβ host factor or Hfq protein. Our previous results suggested that this protein mediates the access of replicase to the 3′-end of the Qβ plus strand RNA. Here we report the results of an evolutionary experiment in which Phage Qβ was adapted to an Escherichia coli Q13 host strain with an inactivated host factor (hfq) gene. This strain initially produced Phage at a titer ≈10,000-fold lower than the wild-type strain and with minute plaque morphology, but after 12 growth cycles, Phage titer and plaque size had evolved to levels near those of the wild-type host. RNAs isolated from adapted Qβ mutants were efficient templates for replicase without host factor in vitro. Electron microscopy showed that mutant RNAs, in contrast to wild-type RNA, efficiently interacted with replicase at the 3′-end in the absence of host factor. The same set of four mutations in the 3′-terminal third of the genome was found in several independently evolved Phage clones. One mutation disrupts the base pairing of the 3′-terminal CCCoh sequence, suggesting that the host factor stimulates activity of the wild-type RNA template by melting out its 3′-end.
