Characterization of Norovirus and Other Human Enteric Viruses in Sewage and Stool Samples Through Next-Generation Sequencing.

This study aimed to optimize a method to identify human enteric viruses in sewage and stool samples using random primed next-generation sequencing. We tested three methods, two employed virus enrichment based on the binding properties of the viral capsid using pig-mucin capture or by selecting viral RNA prior to library preparation through a capture using the SureSelect target enrichment. The third method was based on a non-specific biophysical precipitation with polyethylene glycol. Full genomes of a number of common human enteric viruses including norovirus, rotavirus, husavirus, enterovirus and astrovirus were obtained. In stool samples full norovirus genome were detected as well as partial enterovirus genome. A variety of norovirus sequences was detected in sewage samples, with genogroup II being more prevalent. Interestingly, the pig-mucin capture enhanced not only the recovery of norovirus and rotavirus but also recovery of astrovirus, sapovirus and husavirus. Documenting sewage virome using these methods provides information for molecular epidemiology and may be useful in developing strategies to prevent further spread of viruses

Norwalk Virus–specific Binding to Oyster Digestive Tissues

Specific binding of virus to oysters can selectively concentrate a human pathogen

Assessment of human enteric viruses in cultured and wild bivalve molluscs

Standard and real-time reverse transcription-PCR (rRT-PCR) procedures were used to monitor cultured and wild bivalve molluscs from the Ría de Vigo (NW Spain) for the main human enteric RNA viruses, specifically, norovirus (NoV), hepatitis Avirus (HAV), astrovirus (AsV), rotavirus (RT), enterovirus (EV), and Aichi virus (AiV). The results showed the presence of at least one enteric virus in 63.4% of the 41 samples analyzed. NoV GII was the most prevalent virus, detected in 53.7% of the samples, while NoV GI, AsV, EV, and RV were found at lower percentages (7.3, 12.2, 12.2, and 4.9%, respectively). In general, samples obtained in the wild were more frequently contaminated than those from cultured (70.6 vs. 58.3%) molluscs and were more readily contaminated with more than one virus. However, NoV GI was detected in similar amounts in cultured and wild samples (6.4 × 102 to 3.3 × 103 RNA copies per gram of digestive tissue) while the concentrations of NoV GII were higher in cultured (from 5.6 × 101 to 1.5 × 104 RNA copies per gram of digestive tissue) than in wild (from 1.3 × 102 to 3.4 × 104 RNA copies per gram of digestive tissue) samples. [Int Microbiol 2009; 12(3):145-151

Back pressure effects on variable geometry turbine performances

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Turbochargers are widely used in applications to increase specific power and decrease fuel consumption. However, recent anti-pollution regulations have became stricter and pressed automotive engineers to find new solutions to reduce Nox emissions. Two of these solutions are the catalytic converter and the intercooler system. All these modifications will change the initial matching of the turbocharger performance characteristics to the engine requirements. In this paper, several compressor wheel sizes are investigated to evaluate the turbine/compressor matching. The intercooler and catalytic converter back pressure induced are respectively modeled by a lower duct section downstream the compressor stage and a variable valve downstream the turbine stage. The influences of the different modifications are identified through the loading and the flow coefficients and also on classical turbine performance maps. First, an analogy between compressor wheel size and back pressure effects is underlined. Second, it is shown that initial control settings of turbine nozzle vanes are no longer appropriate with a catalytic converter.vk201

Theoretical dynamic model of norovirus by consumption of contaminated oyster and by inter-human transmission

Noroviruses are involved in winter gastroenteritis epidemics but also in foodborne outbreaks associated with consumption of contaminated oysters. The aim of this work was to better assess the relative effect of inter-human and oyster transmission in coastal populations. Quantitative Risk Assessment was used in order to evaluate food borne transmission. The dose-response, which was estimated from published foodborne outbreaks, illustrates the high infectivity of these viruses. A dynamic model was built that takes into account the two transmission pathways. Initial results show the effect of foodborne pathway on the total number of cases during winter epidemics, and on the cases due to genogroup I and II viruses. This model, based on hypotheses and published data, needs to be further improved in the future, based on real observations data, so as to better assess its use for risk management of shellfish coastal areas.Les norovirus sont impliqués dans les épidémies de gastro-entérites hivernales mais aussi dans les toxiinfections collectives (TIAC) liées à l'ingestion d'huîtres contaminées. L'objectif de cette étude est d'évaluer l'impact de la transmission alimentaire vis-à-vis de la transmission inter-interhumaine dans une population côtière. La transmission alimentaire a été abordée par une Appréciation Quantitative des Risques. Une dose-réponse établie sur des données publiées de TIAC montre la forte infectiosité des norovirus. Un modèle dynamique prenant en compte les deux modes de transmission a été construit. Les premiers résultats montrent que la voie alimentaire peut avoir un impact sur le nombre de cas total en période épidémique et sur les cas attribués au génogroupe I et II. Le modèle, basé sur des hypothèses et des données publiées, devra être poursuivi par un ajustement à des données observées, afin de mieux évaluer la pertinence de mesures de gestion des zones conchylicoles

Magnetic switching in granular FePt layers promoted by near-field laser enhancement

Light-matter interaction at the nanoscale in magnetic materials is a topic of intense research in view of potential applications in next-generation high-density magnetic recording. Laser-assisted switching provides a pathway for overcoming the material constraints of high-anisotropy and high-packing density media, though much about the dynamics of the switching process remains unexplored. We use ultrafast small-angle x-ray scattering at an x-ray free-electron laser to probe the magnetic switching dynamics of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse. We observe that the combination of laser excitation and applied static magnetic field, one order of magnitude smaller than the coercive field, can overcome the magnetic anisotropy barrier between "up" and "down" magnetization, enabling magnetization switching. This magnetic switching is found to be inhomogeneous throughout the material, with some individual FePt nanoparticles neither switching nor demagnetizing. The origin of this behavior is identified as the near-field modification of the incident laser radiation around FePt nanoparticles. The fraction of not-switching nanoparticles is influenced by the heat flow between FePt and a heat-sink layer

Optimisation of a PMAxx™-RT-qPCR Assay and the Preceding Extraction Method to Selectively Detect Infectious Murine Norovirus Particles in Mussels.

Human noroviruses are a major cause for gastroenteritis outbreaks. Filter-feeding bivalve molluscs, which accumulate noroviruses in their digestive tissues, are a typical vector for human infection. RT-qPCR, the established method for human norovirus detection in food, does not allow discrimination between infectious and non-infectious viruses and can overestimate potentially infectious viral loads. To develop a more accurate method of infectious norovirus load estimation, we combined intercalating agent propidium monoazide (PMAxx™)-pre-treatment with RT-qPCR assay using in vitro-cultivable murine norovirus. Three primer sets targeting different genome regions and diverse amplicon sizes were used to compare one-step amplification of a short genome fragment to three two-step long-range RT-qPCRs (7 kbp, 3.6 kbp and 2.3 kbp amplicons). Following initial assays performed on untreated infectious, heat-, or ultraviolet-inactivated murine noroviruses in PBS suspension, PMAxx™ RT-qPCRs were implemented to detect murine noroviruses subsequent to their extraction from mussel digestive tissues; virus extraction via anionic polymer-coated magnetic beads was compared with the proteinase K-dependent ISO norm. The long-range RT-qPCR process detecting fragments of more than 2.3 kbp allowed accurate estimation of the infectivity of UV-damaged murine noroviruses. While proteinase K extraction limited later estimation of PMAxx™ pre-treatment effects and was found to be unsuited to the assay, magnetic bead-captured murine noroviruses retained their infectivity. Genome copies of heat-inactivated murine noroviruses differed by 2.3 log(10) between RT-qPCR and PMAxx™-RT-qPCR analysis in bivalve molluscs, the PMAxx™ pre-treatment allowing a closer approximation of infectious titres. The combination of bead-based virus extraction and PMAxx™ RT-qPCR thus provides a more accurate model for the estimation of noroviral bivalve mollusc contamination than the conjunction of proteinase K extraction and RT-qPCR and has the potential (once validated utilising infectious human norovirus) to provide an added measure of security to food safety authorities in the hazard assessment of potential bivalve mollusc contamination

De Novo Missense Variants in SLC32A1 Cause a Developmental and Epileptic Encephalopathy Due to Impaired GABAergic Neurotransmission

Objective:Rare inherited missense variants inSLC32A1, the gene that encodes the vesicular gamma-aminobutyric acid(GABA) transporter, have recently been shown to cause genetic epilepsy with febrile seizures plus. We aimed to clarifyif de novo missense variants inSLC32A1can also cause epilepsy with impaired neurodevelopment.Methods:Using exome sequencing, we identified four individuals with a developmental and epileptic encephalopathyand de novo missense variants inSLC32A1. To assess causality, we performed functional evaluation of the identifiedvariants in a murine neuronal cell culture model.Results:The main phenotype comprises moderate-to-severe intellectual disability, infantile-onset epilepsy within thefirst 18 months of life, and a choreiform, dystonic, or dyskinetic movement disorder. In silico modeling and functionalanalyses reveal that three of these variants, which are located in helices that line the putative GABA transport pathway,result in reduced quantal size, consistent with impairedfilling of synaptic vesicles with GABA. The fourth variant,located in the vesicular gamma-aminobutyric acid N-terminus, does not affect quantal size, but increases presynapticrelease probability, leading to more severe synaptic depression during high-frequency stimulation. Thus, variants invesicular gamma-aminobutyric acid can impair GABAergic neurotransmission through at least two mechanisms, byaffecting synaptic vesiclefilling and by altering synaptic short-term plasticity.Interpretation:This work establishes de novo missense variants inSLC32A1as a novel cause of a developmental andepileptic encephalopathy