Interaction of rotavirus nonstructural protein NSP5 with the viral replication complex

Rotavirus morphogenesis starts in intracellular inclusion bodies called viroplasms, where synthesis of the11 dsRNA genome segments and their packaging in new viral particles take place. RNA replication is mediated by several viral proteins, of which VP1, the RNA-dependent RNA polymerase, and VP2, the core scaffolding protein, were shown to be sufficient to provide replicase activity in vitro. In vivo, however, viral replication complexes also contain the nonstructural proteins NSP2 and NSP5, which were shown to be essential for replication, to interact with each other and to form viroplasm-like structures (VLS) when coexpressed in uninfected cells. In order to gain a better understanding of the intermediates formed during viral replication, this work focused on the interactions of NSP5 with VP1, VP2 and NSP2. We constructed a tagged form of VP1 and by coimmunoprecipitation experiments we demonstrated that VP1 and NSP5 interact in virus-infected cells as well as in the absence of other viral proteins or viral RNA in cotransfected cells. Using deletion mutants of NSP5 or different fragments of NSP5 fused to EGFP, we identified the 48 C-terminal amino acids as the region essential for interaction with VP1. On the other hand, removal of the C-terminal 15 amino acids from tagged VP1 resulted in a less efficient coimmunoprecipitation with NSP5, suggesting an involvement of the Cterminus of VP1. Interaction of NSP5 with VP2 was investigated by coexpression of the two proteins in uninfected cells, which resulted in a strong hyperphosphorylation of NSP5 and in the formation of VLS, that we named VLS(VP2i) to distinguish them from those induced by NSP2, here designated as VLS(NSP2i). VLS(VP2i) were shown to assemble independently of the phosphorylation degree of NSP5 and to recruit the viroplasm-resident proteins NSP2, VP1, VP2 and VP6 (the protein forming the middle Abstract 4 layer of the virion). Attempts to coimmunoprecipitate NSP5 and VP2 failed both from infected and cotransfected cells. Tagged VP1 was found to localize in VLS (both VP2i and NSP2i) and in viroplasms, and to be able to replace wild-type VP1 structurally by being incorporated into progeny viral particles. Coexpression of different combinations of tagged VP1, NSP5, NSP2 and VP2 showed that the interaction of VP1 with NSP5 is not affected by the other viral proteins and is stronger than the interaction with NSP2. In addition, an inhibitory effect of VP1 on the levels of NSP5 hyperphosphorylation induced by both NSP2 and VP2 was observed. Altogether, these data confirmed an important role for NSP5 in replication, related with the interactions with the two structural proteins essentially involved in viral genome synthesis, and suggested that NSP5 plays a key role in architectural assembly of viroplasms and in recruitment of the other viroplasmic proteins

L'économie sur Wikipédia. Vulgariser et traduire

ope

In vivo site-specific biotinylation of proteins within the secretory pathway using a single vector system

<p>Abstract</p> <p>Background</p> <p>Due to its extremely high strength, the interaction between biotin and (strept)avidin has been exploited for a large number of biotechnological applications. Site-specific biotinylation of proteins <it>in vivo </it>can be achieved by co-expressing in mammalian cells the protein of interest fused to a 15 amino acid long Biotin Acceptor Peptide (BAP) and the bacterial biotin-protein ligase BirA, which specifically recognizes and attaches a biotin to the single lysine residue of the BAP sequence. However, this system is mainly based on the contemporaneous use of two different plasmids or on induction of expression of two proteins through an IRES-driven mechanism.</p> <p>Results</p> <p>We developed a single bigenic plasmid that contains two independent transcriptional units for the co-expression of both the protein tagged with BAP and an engineered version of the BirA enzyme. Upstream of the cDNA encoding BirA, a signal secretion leader sequence was added to allow translocation of the enzyme to the secretory pathway. Three different recombinant antibodies in the scFv format, a membrane bound and secretory truncated IgE Fc fragment and a soluble version of the human IgE high affinity receptor were shown to be efficiently biotinylated and to maintain their binding properties in immunofluorescence microscopy, flow cytometry and ELISA assays.</p> <p>Conclusion</p> <p>The present study shows the universal applicability to both secretory and membrane bound proteins of a single bigenic plasmid to induce the site-specific <it>in vivo </it>biotinylation of target molecules tagged with a short acceptor peptide. These molecules could be easily obtained from supernatants or extracts of mammalian cells and used for a wide range of biological applications.</p

VSV-G-Enveloped Vesicles for Traceless Delivery of CRISPR-Cas9

The method of delivery of CRISPR-Cas9 into target cells is a strong determinant of efficacy and specificity in genome editing. Even though high efficiency of Cas9 delivery is necessary for optimal editing, its long-term and high levels of expression correlate with increased off-target activity. We developed vesicles (VEsiCas) carrying CRISPR-SpCas9 ribonucleoprotein complexes (RNPs) that are efficiently delivered into target cells through the fusogenic glycoprotein of the vesicular stomatitis virus (VSV-G). A crucial step for VEsiCas production is the synthesis of the single guide RNA (sgRNA) mediated by the T7 RNA polymerase in the cytoplasm of producing cells as opposed to canonical U6-driven Pol III nuclear transcription. In VEsiCas, the absence of DNA encoding SpCas9 and sgRNA allows rapid clearance of the nuclease components in target cells, which correlates with reduced genome-wide off-target cleavages. Compared with SpCas9 RNPs electroporation, which is currently the method of choice to obtain transient SpCas9 activity, VEsiCas deliver the nuclease with higher efficiency and lower toxicity. We show that a wide variety of cells can be edited through VEsiCas, including a variety of transformed cells, induced pluripotent stem cells (iPSCs), and cardiomyocytes, in vivo. VEsiCas is a traceless CRISPR-Cas9 delivery tool for efficient and safe genome editing that represents a further advancement toward the therapeutic use of the CRISPR-Cas9 technology

Identification of a small molecule that compromises the structural integrity of viroplasms and rotavirus double-layered particles

Despite the availability of two attenuated vaccines, rotavirus (RV) gastroenteritis remains an important cause of mortality among children in developing countries, causing about 215,000 infant deaths annually. Currently, there are no specific antiviral therapies available. RV is a nonenveloped virus with a segmented double-stranded RNA genome. Viral genome replication and assembly of transcriptionally active double-layered particles (DLPs) take place in cytoplasmic viral structures called viroplasms. In this study, we describe strong impairment of the early stages of RV replication induced by a small molecule known as an RNA polymerase III inhibitor, ML-60218 (ML). This compound was found to disrupt already assembled viroplasms and to hamper the formation of new ones without the need for de novo transcription of cellular RNAs. This phenotype was correlated with a reduction in accumulated viral proteins and newly made viral genome segments, disappearance of the hyperphosphorylated isoforms of the viroplasm-resident protein NSP5, and inhibition of infectious progeny virus production. In in vitro transcription assays with purified DLPs, ML showed dose-dependent inhibitory activity, indicating the viral nature of its target. ML was found to interfere with the formation of higher-order structures of VP6, the protein forming the DLP outer layer, without compromising its ability to trimerize. Electron microscopy of ML-treated DLPs showed dose-dependent structural damage. Our data suggest that interactions between VP6 trimers are essential, not only for DLP stability, but also for the structural integrity of viroplasms in infected cells

CHD8 suppression impacts on histone H3 lysine 36 trimethylation and alters RNA alternative splicing

Disruptive mutations in the chromodomain helicase DNA-binding protein 8 gene (CHD8) have been recurrently associated with autism spectrum disorders (ASDs). Here we investigated how chromatin reacts to CHD8 suppression by analyzing a panel of histone modifications in induced pluripotent stem cell-derived neural progenitors. CHD8 suppression led to significant reduction (47.82%) in histone H3K36me3 peaks at gene bodies, particularly impacting on transcriptional elongation chromatin states. H3K36me3 reduction specifically affects highly expressed, CHD8-bound genes and correlates with altered alternative splicing patterns of 462 genes implicated in ‘regulation of RNA splicing’ and ‘mRNA catabolic process’. Mass spectrometry analysis uncovered a novel interaction between CHD8 and the splicing regulator heterogeneous nuclear ribonucleoprotein L (hnRNPL), providing the first mechanistic insights to explain the CHD8 suppression-derived splicing phenotype, partly implicating SETD2, a H3K36me3 methyltransferase. In summary, our results point toward broad molecular consequences of CHD8 suppression, entailing altered histone deposition/maintenance and RNA processing regulation as important regulatory processes in ASD

A novel allele specific polymerase chain reaction (As-pcr) assay to detect the v1016g knockdown resistance mutation confirms its widespread presence in aedes albopictus populations from Italy

Funding Information: Funding: The study received support from the project ”Sapienza 2017” and JP received support from FCT-Fundação para a Ciência e a Tecnologia, I.P., through national funds in the framework of the project PTDC/BIA-OUT/29477/2017. Funding Information: The study received support from the project ?Sapienza 2017? and JP received support from FCT-Funda??o para a Ci?ncia e a Tecnologia, I.P., through national funds in the framework of the project PTDC/BIA-OUT/29477/2017. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Polymerase chain reaction (PCR)-based genotyping of mutations in the voltage-sensitive sodium channel (vssc) associated with resistance to pyrethroid insecticides is widely used and represents a potential early warning and monitoring system for insecticide resistance arising in mosquito populations, which are vectors of different human pathogens. In the secondary vector Aedes albopictus—an Asian species that has invaded and colonized the whole world, including temperate regions—sequencing of domain II of the vssc gene is still needed to detect the V1016G mutation associated with pyrethroid resistance. In this study we developed and tested a novel allele-specific PCR (AS-PCR) assay to genotype the V1016G mutation in this species and applied it to the analysis of wild populations from Italy. The results confirm the high accuracy of the novel AS-PCR and highlight frequencies of the V1016G allele as >5% in most sampling sites, with peaks of 20–45% in coastal touristic sites where pyrethroid treatments are extensively implemented, mostly for mosquito nuisance reduction. The high frequency of this mutation observed in Italian Ae. albopictus populations should serve as a warning bell, advocating for increased monitoring and management of a phenomenon which risks neutralizing the only weapon today available to counteract (risks of) arbovirus outbreaks.publishersversionpublishe

Identification of Ixodes ricinus blood meals using an automated protocol with high resolution melting analysis (HRMA) reveals the importance of domestic dogs as larval tick hosts in Italian alpine forests

Background In Europe, Ixodes ricinus L. is the main vector of a variety of zoonotic pathogens, acquired through blood meals taken once per stage from a vertebrate host. Defining the main tick hosts in a given area is important for planning public health interventions; however, until recently, no robust molecular methods existed for blood meal identification from questing ticks. Here we improved the time- and cost-effectiveness of an HRMA protocol for blood meal analysis and used it to identify blood meal sources of sheep tick larvae from Italian alpine forests. Methods Nine hundred questing nymphs were collected using blanket-dragging in 18 extensive forests and 12 forest patches close to rural villages in the Province of Trento. Total DNA was either extracted manually, with the QIAamp DNA Investigator kit, or automatically using the KingFisher™ Flex Magnetic Particle Processors (KingFisher Cell and Tissue DNA Kit). Host DNA was amplified with six independent host group real-time PCR reactions and identified by means of HRMA. Statistical analyses were performed in R to assess the variables important for achieving successful identification and to compare host use in the two types of forest. Results Automating DNA extraction improved time- and cost-effectiveness of the HRMA protocol, but identification success fell to 22.4% (KingFisher™) from 55.1% (QIAamp), with larval hosts identified in 215 of 848 questing nymphs; 23 mixed blood meals were noted. However, the list of hosts targeted by our primer sets was extended, improving the potential of the method. Host identification to species or genus level was possible for 137 and 102 blood meals, respectively. The most common hosts were Rodentia (28.9%) and, unexpectedly, Carnivora (28.4%), with domestic dogs accounting for 21.3% of all larval blood meals. Overall, Cetartiodactyla species fed 17.2% of larvae. Passeriformes (14.6%) fed a significantly higher proportion of larvae in forest patches (22.3%) than in extensive forest (9.6%), while Soricomorpha (10.9%) were more important hosts in extensive forest (15.2%) than in forest patches (4.3%). Conclusions The HRMA protocol for blood meal analysis is a valuable tool in the study of feeding ecology of sheep ticks, especially with the cost- and time- reductions introduced here. To our knowledge, we show for the first time that domestic dogs are important larval hosts in the Alps, which may have possible implications for tick-borne disease cycles in urbanized area

Timed rise from floor as a predictor of disease progression in Duchenne muscular dystrophy: An observational study

The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys.A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS).The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p<0.01).Both time to rise from the floor and baseline 6MWT were relevant for predicting 6MWT changes in the group above the age of 7 years, with no interaction between the two measures, as the impact of time to rise from the floor on 6MWT change was similar in the patients below and above 350 m. Our results suggest that, time to rise from the floor can be considered an additional important prognostic factor of 12 month changes on the 6MWT and, more generally, of disease progression

The wide world of technological telerehabilitation for pediatric neurologic and neurodevelopmental disorders – a systematic review

IntroductionThe use of Information and Communication Technology (ICT) for assessing and treating cognitive and motor disorders is promoting home-based telerehabilitation. This approach involves ongoing monitoring within a motivating context to help patients generalize their skills. It can also reduce healthcare costs and geographic barriers by minimizing hospitalization. This systematic review focuses on investigating key aspects of telerehabilitation protocols for children with neurodevelopmental or neurological disorders, including technology used, outcomes, caregiver involvement, and dosage, to guide clinical practice and future research.MethodThis systematic review adhered to PRISMA guidelines and was registered in PROSPERO. The PICO framework was followed to define the search strategy for technology-based telerehabilitation interventions targeting the pediatric population (aged 0–18) with neurological or neurodevelopmental disorders. The search encompassed Medline/PubMed, EMBASE, and Web of Science databases. Independent reviewers were responsible for selecting relevant papers and extracting data, while data harmonization and analysis were conducted centrally.ResultsA heterogeneous and evolving situation emerged from our data. Our findings reported that most of the technologies adopted for telerehabilitation are commercial devices; however, research prototypes and clinical software were also employed with a high potential for personalization and treatment efficacy. The efficacy of these protocols on health or health-related domains was also explored by categorizing the outcome measures according to the International Classification of Functioning, Disability, and Health (ICF). Most studies targeted motor and neuropsychological functions, while only a minority of papers explored language or multi-domain protocols. Finally, although caregivers were rarely the direct target of intervention, their role was diffusely highlighted as a critical element of the home-based rehabilitation setting.DiscussionThis systematic review offers insights into the integration of technological devices into telerehabilitation programs for pediatric neurologic and neurodevelopmental disorders. It highlights factors contributing to the effectiveness of these interventions and suggests the need for further development, particularly in creating dynamic and multi-domain rehabilitation protocols. Additionally, it emphasizes the importance of promoting home-based and family-centered care, which could involve caregivers more actively in the treatment, potentially leading to improved clinical outcomes for children with neurological or neurodevelopmental conditions.Systematic review registrationPROSPERO (CRD42020210663)