Search results for "QPC"
showing 10 items of 73 documents
Assessment of ISO Method 15216 to Quantify Hepatitis E Virus in Bottled Water
2020
Hepatitis E virus (HEV) is one of the causative agents of water-borne human viral hepatitis and considered in Europe an emerging zoonotic pathogen. Analysis of bottled water through a standard method validated for HEV can contribute towards the risk management of this hazard. Putting some recent reports by the European Food Safety Authority in place, this study aimed to assess the performance of the concentration and extraction procedures described in ISO 15216-1:2017 for norovirus and hepatitis A virus on HEV detection. Following the ISO recommendation, the bottled water samples were spiked using serially diluted HEV fecal suspensions together with mengovirus as process control and concent…
Viability RT-qPCR to Distinguish Between HEV and HAV With Intact and Altered Capsids
2018
The hepatitis E virus (HEV) is an emerging pathogen showing a considerable increase in the number of reported cases in Europe mainly related to the ingestion of contaminated food. As with other relevant viral foodborne pathogens, real-time reverse transcriptase polymerase chain reaction (RT-qPCR) is the gold standard for HEV detection in clinical, food, and environmental samples, but these procedures cannot discriminate between inactivated and potentially infectious viruses. Thus, the aim of this study was to develop a viability PCR method to discriminate between native, heat-, and high-pressure processing (HPP)-treated HEV using the hepatitis A virus (HAV) as a cultivable surrogate. To thi…
Optimization of PMAxx pretreatment to distinguish between human norovirus with intact and altered capsids in shellfish and sewage samples
2018
Shellfish contamination by human noroviruses (HuNoVs) is a serious health and economic problem. Recently an ISO procedure based on RT-qPCR for the quantitative detection of HuNoVs in shellfish has been issued, but these procedures cannot discriminate between inactivated and potentially infectious viruses. The aim of the present study was to optimize a pretreatment using PMAxx to better discriminate between intact and heat-treated HuNoVs in shellfish and sewage. To this end, the optimal conditions (30 min incubation with 100 μM of PMAxx and 0.5% of Triton, and double photoactivation) were applied to mussels, oysters and cockles artificially inoculated with thermally-inactivated (99 °C for 5 …
Hepatitis E virus in lettuce and water samples: A method-comparison study
2017
The hepatitis E virus (HEV), which is an increasing cause of acute viral hepatitis in Europe, is a zoonotic virus that is mainly transmitted through contaminated water, consumption of raw or undercooked meat from pigs or wild boar, blood transfusion, and organ transplantation. Although the role of HEV transmission through contaminated produce has not been confirmed, the presence of HEV has been reported in irrigation waters and in vegetables. The present study used a World Health Organization (WHO) international standard and clinical samples to evaluate the performance characteristics of three RT-qPCR assays for detection and quantification of HEV. Two of the evaluated assays provided good …
Seasonal and spatial dynamics of enteric viruses in wastewater and in riverine and estuarine receiving waters
2018
International audience; Enteric viruses represent a global public health threat and are implicated in numerous foodborne andwaterborne disease outbreaks. Nonetheless, relatively little is known of their fate and stability in the environment. In this studywe used carefully validatedmethods tomonitor enteric viruses, namely adenovirus (AdV), JC polyomavirus (JCV), noroviruses (NoVs), sapovirus (SaV) and hepatitis A and E viruses (HAV and HEV) fromwastewater source to beaches and shellfish beds. Wastewater influent and effluent, surface water, sediment and shellfish samples were collected in the Conwy catchment (North Wales, UK) once a month for one year. High concentrations of AdV and JCV wer…
High Nutrient Concentration Can Induce Virulence Factor Expression and Cause Higher Virulence in an Environmentally Transmitted Pathogen
2016
Environmentally transmitted opportunistic pathogens shuttle between two substantially different environments: outside-host and within-host habitats. These environments differ from each other especially with respect to nutrient availability. Consequently, the pathogens are required to regulate their behavior in response to environmental cues in order to survive, but how nutrients control the virulence in opportunistic pathogens is still poorly understood. In this study, we examined how nutrient level in the outside-host environment affects the gene expression of putative virulence factors of the opportunistic fish pathogen Flavobacterium columnare. The impact of environmental nutrient concen…
MARTX Toxin in the Zoonotic Serovar of Vibrio vulnificus Triggers an Early Cytokine Storm in Mice
2017
Vibrio vulnificus biotype 2-serovar E is a zoonotic clonal complex that can cause death by sepsis in humans and fish. Unlike other biotypes, Bt2 produces a unique type of MARTXVv (Multifunctional-Autoprocessive-Repeats-in-Toxin; RtxA13), which is encoded by a gene duplicated in the pVvBt2 plasmid and chromosome II. In this work, we analyzed the activity of this toxin and its role in human sepsis by performing in vitro, ex vivo, and in vivo assays. First, we demonstrated that the ACD domain, present exclusively in this toxin variant, effectively has an actin-cross-linking activity. Second, we determined that the whole toxin caused death of human endotheliocytes and monocytes by lysis and apo…
Do shifts in life strategies explain microbial community responses to increasing nitrogen in tundra soil?
2016
Subarctic tundra soils store large quantities of the global organic carbon (C) pool as the decomposition of plant litter and soil organic matter is limited by low temperatures and limiting nutrients. Mechanisms that drive organic matter decomposition are still poorly understood due to our limited knowledge of microbial communities and their responses to changing conditions. In subarctic tundra large grazers, in particular reindeer, exert a strong effect on vegetation and nutrient availability causing drastic nutrient pulses in the soils located along the migratory routes. Here we studied the effect of increased nitrogen (N) availability on microbial community structure and activities by lab…
Recurrent inoculation: a strategy for a better survival of Pseudomonas fluorescens strain in soil
2022
A growing interest is shown for microbial inoculants as a promising alternative to agrochemicals for sustainable agricultural. However, biotic and abiotic stresses are known to affect their establishment and effectiveness, leading to inconsistent performance in field conditions. At the same time, a poor survival of the strain is often observed, which constitutes a main hamper for bacterial inoculant development. We hypothesize that recurrent inoculations would improve the survival of the strain in soil. For this purpose, we tested different scenarios of inoculation of the plant growth promoting rhizobacteria Pseudomonas fluorescens in soil microcosms: a single inoculation, two inoculations …
Polyoxypregnanes as safe, potent, and specific ABCB1-inhibitory pro-drugs to overcome multidrug resistance in cancer chemotherapy in vitro and in vivo
2021
Multidrug resistance (MDR) mediated by ATP binding cassette subfamily B member 1 (ABCB1) is significantly hindering effective cancer chemotherapy. However, currently, no ABCB1-inhibitory drugs have been approved to treat MDR cancer clinically, mainly due to the inhibitor specificity, toxicity, and drug interactions. Here, we reported that three polyoxypregnanes (POPs) as the most abundant constituents of Marsdenia tenacissima (M. tenacissima) were novel ABCB1-modulatory pro-drugs, which underwent intestinal microbiota-mediated biotransformation in vivo to generate active metabolites. The metabolites at non-toxic concentrations restored chemosensitivity in ABCB1-overexpressing cancer cells v…