Results 76-100 of 212 in SARS-CoV-2
  1. A main clinical parameter of COVID-19 pathophysiology is hypoxia. Here we show that hypoxia decreases the attachment of the receptor binding domain (RBD) and the S1 subunit (S1) of the spike protein of SARS-CoV-2 to epithelial cells. In Vero E6 cells, hypoxia reduces the protein levels of ACE2 and neuropilin-1 (NRP1), which might in part explain the observed reduction of the infection rate. In addition, hypoxia inhibits the binding of the spike to NCI-H460 human lung epithelial cells by decreasing the cell surface levels of heparan sulfate (HS), a known attachment receptor of SARS-CoV-2. This interaction is also reduced by lactoferrin, a glycoprotein that blocks HS moieties on the cell surface. The expression of syndecan-1, an HS-containing proteoglycan expressed in lung, is inhibited by hypoxia on a HIF-1α-dependent manner. Hypoxia or deletion of syndecan-1 results in reduced binding of the RBD to host cells. Our study indicates that hypoxia acts to prevent SARS-CoV-2 infection, suggesting that the hypoxia signaling pathway might offer therapeutic opportunities for the treatment of COVID-19.
    Date: 2021-01-11
    Authors: Prieto-Fernández E, Egia-Mendikute L, Vila-Vecilla L, Bosch A, Barreira-Manrique A, Lee SY, García-del Río A, Antoñana-Vildosola A, Jiménez-Lasheras B, Moreno-Cugnon L, Jiménez-Barbero J, Berra E, Ereño-Orbea J, Palazon A.
    Ref: bioRxiv
  2. Saliva is an attractive specimen type for asymptomatic surveillance of COVID-19 in large populations due to its ease of collection and its demonstrated utility for detecting RNA from SARS-CoV-2. Multiple saliva-based viral detection protocols use a direct-to-RT-qPCR approach that eliminates nucleic acid extraction but can reduce viral RNA detection sensitivity. To improve test sensitivity while maintaining speed, we developed a robotic nucleic acid extraction method for detecting SARS-CoV-2 RNA in saliva samples with high throughput. Using this assay, the Free Asymptomatic Saliva Testing (IGI-FAST) research study on the UC Berkeley campus conducted 11,971 tests on supervised self-collected saliva samples and identified rare positive specimens containing SARS-CoV-2 RNA during a time of low infection prevalence. In an attempt to increase testing capacity, we further adapted our robotic extraction assay to process pooled saliva samples. We also benchmarked our assay against the gold standard, nasopharyngeal swab specimens. Finally, we designed and validated a RT-qPCR test suitable for saliva self-collection. These results establish a robotic extraction-based procedure for rapid PCR-based saliva testing that is suitable for samples from both symptomatic and asymptomatic individuals.
    Date: 2021-01-11
    Authors: Hamilton JR, Stahl EC, Tsuchida CA, Lin-Shiao E, Tsui CK, Pestal K, Gildea HK, Witkowsky LB, Moehle EA, McDevitt SL, McElroy M, Keller A, Sylvain I, Hirsh A, Ciling A, Ehrenberg AJ, Ringeisen BR, Huberty G, Urnov FD, Giannikopoulos P, Doudna JA, IGI SARS-CoV-2 consortium.
    Ref: medRxiv
  3. ABSTRACT The continued resurgence of the COVID-19 pandemic with multiple variants underlines the need for diagnostic strategies, that are easily adapatable to the changing virus. Here, we have designed and developed toehold RNA-based sensors across the SARS-CoV-2 genome for direct and ultrasensitive detection of the virus and its prominent variants. In our assay, isothermal amplification of a fragment of SARS-CoV-2 RNA coupled with activation of our biosensors leads to a conformational switch in the sensor. This leads to translation of a reporter-protein e.g. LacZ or Nano-lantern that is easily detected using color/luminescence. By optimizing RNA-amplification and biosensor-design, we have generated a highly-sensitive diagnostic assay; with sensitivity down to attomolar SARS-CoV-2 RNA. As low as 100 copies of viral RNA are detected with development of bright color that is easily visualized by the human eye, or a simple cell phone camera as well as quantified using a spectrophotometer. This makes our assay deployable all the way from a well equiped laboratory to a low-resource setting anywhere in the world. Finally, this PHA sed N ASBA- T ranslation O ptical M ethod (PHANTOM) using our engineered RNA biosensors efficiently detects the presence of viral RNA in human patient samples, correlating well with Ct values from RT-qPCR tests. This work presents a powerful and universally accessible strategy for detecting Covid-19 and its prominent variants. This strategy is easily adaptable to further viral evolution and brings RNA-based bioengineering to centerstage.
    Date: 2021-01-08
    Authors: Chakravarthy A, Anirudh K, George G, Ranganathan S, Shettigar N, Suchitta U, Palakodeti D, Gulyani A, Ramesh A.
    Ref: medRxiv
  4. The worldwide outbreak of the COVID-19 has become a global pandemic resulting in millions of confirmed cases and hundreds of thousands of deaths. To face such a global crisis, bioinformatics has played a key role in the diagnosis, follow-up, prognosis and treatment of COVID-19-infected patients.A novel bioinformatic tool for metagenomic analysis of whole genomes is proposed in this paper that is composed of three projections: global, clustering and genomic index. For each projection, key modules are described. Global projection provides various combinatorial distributions for a whole genome of N length, and the m-mer scheme partitions this sequence as M segments on 1D, 2D and 3D density matrices for multiple projections. Clustering projections based on distributions from global projections make special filters extract specific parts as probability eigenvalues. Genomic index projection provides comprehensive technologies under the theory of information entropy, and a list of measuring entropies are included, such as combinatorial entropy CE, integrated entropy IE, mean entropy ME and topological entropy TE. Three projections provide unified information to describe complicated functions, internal structures and refined variations for multiple groups of SARS-CoV-2 on variations and other genomes in comparisons.The outputs of three projections are illustrated on variant maps to support category, clustering, classification and establishing root activities for refined quantitative operations from bottom to top strategy.
    Date: 2021-01-08
    Authors: Zheng J, Liu J.
    Ref: Research Square
  5. The steep climbing of victims caused by the new coronavirus disease 2019 (COVID-19) throughout the planet is sparking an unprecedented effort to identify effective therapeutic regimens to tackle the pandemic. The SARS-CoV-2 virus is known to gain entry into various cell types through the binding of one of its surface proteins (spike) to the host Angiotensin-Converting Enzyme 2 (ACE2). Thus, spike-ACE2 interaction represents a major target for vaccines and antiviral drugs. A novel method has been recently described by some of the authors to pharmacologically downregulate the expression of target proteins at the post-translational level. This technology builds on computational advancements in the simulation of folding mechanisms to rationally block protein expression by targeting folding intermediates, hence hampering the folding process. Here, we report the all-atom simulations of the entire sequence of events underlying the folding pathway of ACE2. Our data revealed the existence of a folding intermediate showing two druggable pockets hidden in the native conformation. Both pockets were targeted by a virtual screening repurposing campaign aimed at quickly identifying drugs capable to decrease the expression of ACE2. We identified four compounds capable of lowering ACE2 expression in Vero cells in a dose-dependent fashion. All these molecules were found to inhibit the entry into cells of a pseudotyped retrovirus exposing the SARS-CoV-2 spike protein. Importantly, the antiviral activity has been tested against live SARS-CoV-2 (MEX-BC2/2020 strain). One of the selected drugs (Artefenomel) could completely prevent cytopathic effects induced by the presence of the virus, thus showing antiviral activity against SARS-CoV-2. Ongoing studies are further evaluating the possibility of repurposing these drugs for the treatment of COVID-19.
    Date: 2021-01-05
    Authors: Massignan T, Boldrini A, Terruzzi L, Spagnolli G, Astolfi A, Bonaldo V, Pischedda F, Pizzato M, Lolli G, Barreca ML, Biasini E, Faccioli P, Pieri L.
    Ref: arXiv
  6. At the very beginning of the new decade, the COVID-19 pandemic has badly hit modern human societies. SARS-CoV-2, the causative agent of COVID-19 carries dozens of new mutations in its genome. Herein, we made an effort to find new antiviral peptides (AVPs) against SARS-CoV-2. Gladly, with the help of Machine Learning algorithms, and Supported Vector Machine, we have invented three new AVPs against the SARS-CoV-2. Antiviral peptides viz. , Seq12, Seq12m, and Seq13m can block the receptor binding domain (RBD) of the SARS-CoV-2, necessary for communication with the angiotensin-converting enzyme 2 (ACE2). In addition, these AVPs retain their antiviral properties, even after the insertion of dozens of new mutations (Rosetta, and FoldX based) in the RBD. Further, Seq12, and Seq12m showed negligible cytotoxicity. Besides, the binding free energy calculated using MM-PB/GBSA method is also in agreement with the molecular docking studies performed using HADDOCK. Furthermore, the molecular interactions between AVPs and the viral membrane protein (M) also showed a thermodynamically favorable interaction, suggesting it could eventually inhibit the viral re-packaging process. In conclusion, this study suggests AVPs viz. , Seq12, Seq12m, and Seq13m embrace importance as a potential anti-SARS-CoV-2 therapeutic. These AVPs could also aid virus diagnostic tools in the future.
    Date: 2020-12-28
    Authors: Dutta K, Elmezayen AD, Alobaidi A, Zhu W, Morojava O, Shityakov S, Khalifa I.
    Ref: Research Square
  7. The COVID-19 pandemic caused by SARS-CoV-2 has infected millions worldwide and there is an urgent need to increase our diagnostic capacity to identify infected cases. Although RT-qPCR remains the gold standard for SARS-CoV-2 detection, this method requires specialised equipment in a diagnostic laboratory and has a long turn-around time to process the samples. To address this, several groups have recently reported development of loop-mediated isothermal amplification (LAMP) as a simple, low cost and rapid method for SARS-CoV-2 detection. Herein we present a comparative analysis of three LAMP-based assays that target different regions of the SARS-CoV-2: ORF1ab RdRP, ORF1ab nsp3 and Gene N. We perform a detailed assessment of their sensitivity, kinetics and false positive rates for SARS-CoV-2 diagnostics in LAMP or RT-LAMP reactions, using colorimetric or fluorescent detection. Our results independently validate that all three assays can detect SARS-CoV-2 in 30 minutes, with robust accuracy at detecting as little as 1000 RNA copies and the results can be visualised simply by color changes. We also note the shortcomings of these LAMP-based assays, including variable results with shorter reaction time or lower load of SARS-CoV-2, and false positive results in some experimental conditions. Overall for RT-LAMP detection, the ORF1ab RdRP and ORF1ab nsp3 assays have higher sensitivity and faster kinetics for detection, whereas the Gene N assay exhibits no false positives in 30 minutes reaction time. This study provides validation of the performance of LAMP-based assays for SARS-CoV-2 detection, which have important implications in development of point-of-care diagnostic for SARS-CoV-2.
    Date: 2020-12-22
    Authors: Urrutia-Cabrera D, Liou RH, Chan J, Hung SS, Hewitt AW, Martin KR, Kwan P, Wong RC.
    Ref: medRxiv
  8. ABSTRACT The well-recognized genome editing ability of the CRISPR-Cas system has triggered significant advances in CRISPR diagnostics. This has prompted an interest in developing new biosensing applications for nucleic acid detection. Recently, such applications have been engineered for detection of SARS-CoV-2. Increased demand for testing and consumables of RT-qPCR assays has led to the use of alternate testing options in some cases. Here we evaluate the accuracy and performance of a novel fluorescence based assay that received EUA authorization from the FDA for detecting SARS-CoV-2 in clinical samples. The Specific High-Sensitivity Enzymatic Reporter UnLOCKing (SHERLOCK) technology forms the basis of the Sherlock CRISPR SARS-CoV-2 kit using the CRISPR-Cas13a system. Our experimental strategy included selection of COVID-19 patient samples from previously validated RT-qPCR assays. Positive samples were selected based on a broad range of cycle thresholds. A total of 50 COVID-19 patient samples were correctly diagnosed with 100% accuracy (relative fluorescence ratios: N gene 95% CI 23.2-36.3, ORF1ab gene 95% CI 27.6-45.4). All controls, including RNase P, showed expected findings. Overall ratios were robustly distinct between positive and negative cases relative to the pre-established 5-fold change in fluorescence read output. We have evaluated the accuracy of detecting conserved targets of SARS-CoV-2 across a range of viral loads using the SHERLOCK CRISPR collateral detection reaction in a clinical setting. These findings demonstrate encouraging results, especially at a time when COVID-19 clinical diagnosis is in high demand; often with limited resources. This approach highlights new thinking in infectious disease identification and can be expanded to measure nucleic acids in other clinical isolates.
    Date: 2020-12-19
    Authors: Khan WA, Barney RE, Tsongalis GJ.
    Ref: medRxiv
  9. The endo-lysosomal pathway plays an important role in pathogen clearance and both bacteria and viruses have evolved complex mechanisms to evade this host system. Here, we describe a novel aspect of coronaviral infection, whereby the master transcriptional regulator of lysosome biogenesis – TFEB – is targeted for proteasomal-mediated degradation upon viral infection. Through mass spectrometry analysis and an unbiased siRNA screen, we identify that TFEB protein stability is coordinately regulated by the E3 ubiquitin ligase subunit DCAF7 and the PAK2 kinase. In particular, viral infection triggers marked PAK2 activation, which in turn, phosphorylates and primes TFEB for ubiquitin-mediated protein degradation. Deletion of either DCAF7 or PAK2 blocks viral-mediated TFEB degradation and protects against viral-induced cytopathic effects. We further derive a series of small molecules that interfere with the DCAF7-TFEB interaction. These agents inhibit viral-triggered TFEB degradation and demonstrate broad anti-viral activities including attenuating in vivo SARS-CoV-2 infection. Together, these results delineate a viral-triggered pathway that disables the endogenous cellular system that maintains lysosomal function and suggest that small molecule inhibitors of the E3 ubiquitin ligase DCAF7 represent a novel class of endo-lysosomal, host-directed, anti-viral therapies.
    Date: 2021-04-23
    Authors: Liu Y, Lear T, Larsen M, Lin B, Cao Q, Alfaras I, Kennerdell J, Salminen L, Camarco D, Lockwood K, Ma J, Liu J, Tan J, Myerburg M, Chen Y, Croix CS, Sekine Y, Evankovich J, Finkel T, Chen B.
    Ref: Research Square
  10. Comprehensive libraries of plasmids for SARS-CoV-2 proteins with various tags (e.g. Strep, HA, Turbo) are now available. They enable the identification of numerous potential protein-protein interactions between the SARS-CoV-2 virus and host proteins. To facilitate further cellular investigations, notably by imaging techniques, we present here a large library of SARS CoV-2 protein constructs fused with green and red fluorescent proteins and their initial characterization in various human cell lines including lung epithelial cell models (A549, BEAS-2B), as well as in budding yeast. The localization of a few SARS-CoV-2 proteins matches their proposed interactions with host proteins. These include the localization of Nsp13 to the centrosome, Orf3a to late endosomes, and Orf9b to mitochondria.
    Date: 2020-12-19
    Authors: Miserey-Lenkei S, Trajkovic K, D'Ambrosio JM, Patel AJ, Čopič A, Mathur P, Schauer K, Goud b, Albanèse V, Gautier R, Subra M, Kovacs D, Barelli H, Antonny B.
    Ref: bioRxiv
  11. The coronaviruses responsible for severe acute respiratory syndrome (SARS-CoV), COVID-19 (SARS-CoV-2), Middle East respiratory syndrome (MERS-CoV), and other coronavirus infections express a nucleocapsid protein (N) that is essential for viral replication, transcription, and virion assembly. Phosphorylation of N from SARS-CoV by glycogen synthase kinase 3 (GSK-3) is required for its function and inhibition of GSK-3 with lithium impairs N phosphorylation, viral transcription, and replication. Here we report that the SARS-CoV-2 N protein contains GSK-3 consensus sequences and that this motif is conserved in diverse coronaviruses, despite limited overall sequence conservation, raising the possibility that SARS- CoV-2 may be sensitive to GSK-3 inhibitors including lithium. We conducted a retrospective analysis of lithium use in patients from three major health systems who were PCR tested for SARS-CoV-2. We found that patients taking lithium have a significantly reduced risk of COVID- 19 (odds ratio = 0.51 [0.34 - 0.76], p = 0.001). We also show that the SARS-CoV-2 N protein is phosphorylated by GSK-3. Knockout of GSK3A and GSK3B demonstrates that GSK-3 is essential for N phosphorylation. Alternative GSK-3 inhibitors block N phosphorylation and impair replication in SARS-CoV-2 infected lung epithelial cells in a cell-type dependent manner. Targeting GSK-3 may therefore provide a new approach to treat COVID-19 and future coronavirus outbreaks.
    Date: 2021-02-22
    Authors: Liu X, Verma A, Ramage H, Garcia G, Myers RL, Lucas A, Michaelson JJ, Coryell W, Kumar A, Charney A, Kazanietz MG, Rader DJ, Ritchie MD, Berrettini WH, Damoiseaux R, Arumugaswami V, Schultz D, Cherry S, Klein PS.
    Ref: medRxiv
  12. We report on genosensors to detect an ssDNA sequence from the SARS-CoV-2 genome, which mimics the GU280 gp10 gene (coding the viral nucleocapsid phosphoprotein), using four distinct principles of detection and treating the data with information visualization and machine learning techniques. Genosensors were fabricated on either gold (Au) interdigitated electrodes for electrical and electrochemical measurements or on Au nanoparticles on a glass slide for optical measurements. They contained a matrix of 11-mercaptoundecanoic acid (11-MUA) self-assembled monolayer (SAM) onto which a layer of capture probe (cpDNA) sequence was immobilized. Detection was performed using electrical and electrochemical impedance spectroscopies and localized surface plasmon resonance (LSPR). The highest sensitivity was reached with impedance spectroscopy, including using a low-cost (US$ 100) homemade impedance analyzer. Complementary ssDNA sequences were detected with a detection limit of 0.5 aM (0.3 copy/μL). This performance may be attributed to the high sensitivity of the electrical impedance technique combined with an appropriate arrangement of the sequences on the electrodes and hybridization between the complementary sequences, as inferred from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The selectivity of the genosensor was confirmed by plotting the impedance spectroscopy data with a multidimensional projection technique (Interactive Document Mapping, IDMAP), where a clear separation was observed among the samples of the complementary DNA sequence at various concentrations and from buffer samples containing a non-complementary sequence and other DNA biomarkers. The diagnosis of SARS-CoV-2 mimicking sequences was also achieved with machine learning techniques applied to scanning electron microscope images taken from genosensors exposed to distinct concentrations of the complementary ssDNA sequences. In summary, the genosensors proposed here are promising for detecting SARS-CoV-2 genetic material (RNA) in biological fluids in point-of-care settings.
    Date: 2020-12-14
    Authors: Soares JC, Soares AC, Rodrigues VC, Oiticica PRA, Raymundo-Pereira PA, Bott-Neto JL, Buscaglia LA, Castro LDC, Ribas LC, Scabini L, Brazaca LC, Correa DS, Mattoso LHC, de Oliveira MCF, Carvalho APLF, Carrilho E, Bruno OM, Melendez M, N. Oliveira Jr O.
    Ref: ChemRxiv
  13. Commonly used RT-qPCR-based SARS-CoV-2 diagnostics require 2-3 separate reactions or rely on detection of a single viral target, adding time and cost or risk of false-negative results. Currently, no test combines detection of widely used SARS-CoV-2 E- and N-gene targets and a sample control in a single, multiplexed reaction. We developed the IGI-LuNER RT-qPCR assay using the Lu na Probe Universal One-Step RT-qPCR master mix with publicly available primers and probes to detect SARS-CoV-2 N gene, E gene, and human RNase P ( NER ). This combined, cost-effective test can be performed in 384-well plates with detection sensitivity suitable for clinical reporting, and will aid in future sample pooling efforts, thus improving throughput of SARS-CoV-2 detection. Graphical Abstract
    Date: 2020-12-11
    Authors: Stahl EC, Tsuchida CA, Hamilton JR, Lin-Shiao E, McDevitt SL, Moehle EA, Witkowsky LB, Tsui CK, Pestal K, Gildea HK, McElroy M, Keller A, Sylvain I, Williams C, Hirsh A, Ciling A, Ehrenberg AJ, Urnov FD, Ringeisen BR, Giannikopoulos P, Doudna JA, IGI SARS-CoV-2 consortium.
    Ref: medRxiv
  14. Background In the ongoing pandemic situation of COVID-19, serological tests can complement the molecular diagnostic methods, and can be one of the important tools of sero-surveillance and vaccine evaluation. Aim To develop and evaluate a rapid SARS-CoV-2 specific ELISA for detection of anti-SARS-CoV2 IgG from patient’s biological samples. Methods In order to develop the ELISA, three panels of samples (n=184) have been used: panel 1 (n=19) and panel 2 (n=60) were collected from RT-PCR positive patients within 14 and after 14 days of onset of clinical symptoms respectively, whereas panel 3 consisted of negative samples (n=105) collected either from healthy donors or pre-pandemic dengue patients. As a capturing agent full-length SARS-CoV2 specific recombinant nucleocapsid was immobilized. Commercial SARS-CoV2 IgG kit based on chemiluminescent assay was used for the selection of samples and optimization of the assay. The threshold cut-off point, inter-assay and intra-assay variations were determined. The total assay time for this in-house ELISA was set for 30 minutes. Results The assay time was set at a total of 30 minutes with the sensitivity of 84% (95% confidence interval, CI, 60.4%, 96.6%) and 98% (95% CI, 91.1%, 100.0%), for panel 1 and 2 respectively, with over all 94.9% sensitivity (95% CI 87.5%, 98.6%). Moreover, the clinical specificity is 97.1% (95% CI, 91.9%, 99.4%) with no cross reaction with dengue sample. The overall positive and negative predictive values are 96.2% (95% CI 89.2%, 99.2%) and 96.2% (95% CI, 90.6% 99.0%) respectively. In-house ELISA demonstrated 100% positive and negative percent agreement with ROCHE (Elecsys; Anti-SARS-CoV-2), with a Cohen’s kappa value of 1.00 (very strong agreement), while comparing 13 positive and 17 negative confirmed cases. Conclusion The assay is rapid and can be applied as one of the early and retrospective sero-monitoring tools in all over the affected areas.
    Date: 2020-12-11
    Authors: Sil BK, Oishee MJ, Haq MA, Jahan N, Ali T, Khandker SS, Kobatake E, Mie M, Khondoker MU, Jamiruddin MR, Adnan N.
    Ref: medRxiv
  15. The spike D614G mutation increases SARS-CoV-2 infectivity, viral load, and transmission but the molecular mechanism underlying these effects remains unclear. We report here that spike is trafficked to lysosomes and that the D614G mutation enhances the lysosomal sorting of spike and the lysosomal accumulation of spike-positive punctae in SARS-CoV-2-infected cells. Spike trafficking to lysosomes is an endocytosis-independent, V-ATPase-dependent process, and spike-containing lysosomes drive lysosome clustering but display poor lysotracker labeling and reduced uptake of endocytosed materials. These results are consistent with a lysosomal pathway of coronavirus biogenesis and raise the possibility that a common mechanism may underly the D614G mutation’s effects on spike protein trafficking in infected cells and the accelerated entry of SARS-CoV-2 into uninfected cells.
    Date: 2020-12-09
    Authors: Guo C, Tsai S, Ai Y, Li M, Pekosz A, Cox A, Atai N, Gould SJ.
    Ref: bioRxiv
  16. Improved molecular screening and diagnostic tools are needed to substantially increase SARS-CoV-2 testing capacity and throughput while reducing the time to receive test results. Here we developed multiplex reverse transcriptase polymerase chain reaction (m-RT-PCR) for detection of SARS-CoV-2 using rapid DNA electrophoresis and alternatively using multiplex viral sequencing (mVseq). For RNA specimens extracted from nasopharyngeal (NP) swabs in viral transport media (VTM), our assays achieved a sensitivity for SARS-CoV-2 detection corresponding to cycle threshold (Ct) of 37.2 based on testing of these specimens using quantitative reverse transcription PCR (RT-qPCR). For NP swab-VTM specimens without prior RNA extraction, sensitivity was reduced to Ct of 31.6, which was due to lower concentration of SARS-CoV-2 genome copies in VTM compared to RNA-extracted samples. Assay turnaround time was 60 minutes using rapid gel electrophoresis, 90 minutes using Agilent Bioanalyzer, and 24-48 hours using Illumina sequencing, the latter of which required a second PCR to produce a sequence-ready library using m-RT-PCR products as the template. Our assays can be employed for high-throughput sequencing-based detection of SARS-CoV-2 directly from a clinical specimen without RNA isolation, while ease-of-use and low cost of the electrophoresis-based readout enables screening, particularly in resource-constrained settings.
    Date: 2020-12-07
    Authors: Gandotra N, Tikhonova I, Cheemarla NR, Knight J, Foxman E, Giraldez A, Shen P, Bilguvar K, Scharfe C.
    Ref: medRxiv
  17. Summary Over the past 20 years, the emergence of three highly pathogenic coronaviruses (CoV) – SARS-CoV, MERS-CoV, and most recently SARS-CoV-2 – has shown that CoVs pose a serious risk to human health and highlighted the importance of developing effective therapies against them. Similar to other viruses, CoVs are dependent on host factors for their survival and replication. We hypothesized that evolutionarily distinct CoVs may exploit similar host factors and pathways to support their replication cycle. Here, we conducted two independent genome-wide CRISPR/Cas9 knockout screens to identify pan-CoV host factors required for the replication of both endemic and emerging CoVs, including the novel CoV SARS-CoV-2. Strikingly, we found that several autophagy-related genes, including the immunophilin FKBP8, TMEM41B, and MINAR1, were common host factors required for CoV replication. Importantly, inhibition of the immunophilin family with the compounds Tacrolimus, Cyclosporin A, and the non-immunosuppressive derivative Alisporivir, resulted in dose-dependent inhibition of CoV replication in primary human nasal epithelial cell cultures that resemble the natural site of virus replication. Overall, we identified host factors that are crucial for CoV replication and demonstrate that these factors constitute potential targets for therapeutic intervention by clinically approved drugs.
    Date: 2021-02-24
    Authors: Kratzel A, Kelly JN, Brueggemann Y, Portmann J, V’kovski P, Todt D, Ebert N, Steinmann E, Dijkman R, Zimmer G, Pfaender S, Thiel V.
    Ref: bioRxiv
  18. McQ is a SARS-CoV-2 quantification assay that couples early-stage barcoding with high-throughput sequencing to enable multiplexed processing of thousands of samples. McQ is based on homemade enzymes to enable low-cost testing of large sample pools, circumventing supply chain shortages. Implementation of cost-efficient high-throughput methods for detection of RNA viruses such as SARS-CoV-2 is a potent strategy to curb ongoing and future pandemics. Here we describe Multiplexed SARS-CoV-2 Quantification platform (McQ), an in-expensive scalable framework for SARS-CoV-2 quantification in saliva samples. McQ is based on the parallel sequencing of barcoded amplicons generated from SARS- CoV-2 genomic RNA. McQ uses indexed, target-specific reverse transcription (RT) to generate barcoded cDNA for amplifying viral- and human-specific regions. The barcoding system enables early sample pooling to reduce hands-on time and makes the ap-proach scalable to thousands of samples per sequencing run. Robust and accurate quantification of viral load is achieved by measuring the abundance of Unique Molecular Identifiers (UMIs) introduced during reverse transcription. The use of homemade reverse transcriptase and polymerase enzymes and non-proprietary buffers reduces RNA to library reagent costs to 92 cents/sample and circumvents potential supply chain short-ages. We demonstrate the ability of McQ to robustly quantify various levels of viral RNA in 838 clinical samples and accu-rately diagnose positive and negative control samples in a test-ing workflow entailing self-sampling and automated RNA ex-traction from saliva. The implementation of McQ is modular, scalable and could be extended to other pathogenic targets in future.
    Date: 2020-12-04
    Authors: Vonesch SC, Bredikhin D, Dobrev N, Villacorta L, Kleinendorst R, Cacace E, Flock J, Frank M, Jung F, Kornienko J, Mitosch K, Osuna-López M, Zimmermann J, Göttig S, Hamprecht A, Kräusslich H, Knop M, Typas A, Steinmetz LM, Benes V, Remans K, Krebs AR.
    Ref: medRxiv
  19. ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19. SARS-CoV-2 relies on cellular RNA-binding proteins (RBPs) to replicate and spread, although which RBPs control SARS-CoV-2 infection remains largely unknown. Here, we employ a multi-omic approach to identify systematically and comprehensively which cellular and viral RBPs are involved in SARS-CoV-2 infection. We reveal that the cellular RNA-bound proteome is remodelled upon SARS-CoV-2 infection, having widespread effects on RNA metabolic pathways, non-canonical RBPs and antiviral factors. Moreover, we apply a new method to identify the proteins that directly interact with viral RNA, uncovering dozens of cellular RBPs and six viral proteins. Amongst them, several components of the tRNA ligase complex, which we show regulate SARS-CoV-2 infection. Furthermore, we discover that available drugs targeting host RBPs that interact with SARS-CoV-2 RNA inhibit infection. Collectively, our results uncover a new universe of host-virus interactions with potential for new antiviral therapies against COVID-19.
    Date: 2020-11-25
    Authors: Kamel W, Noerenberg M, Cerikan B, Chen H, Järvelin AI, Kammoun M, Lee J, Shuai N, Garcia-Moreno M, Andrejeva A, Deery MJ, Neufeldt CJ, Cortese M, Knight ML, Lilley KS, Martinez J, Davis I, Bartenschlager R, Mohammed S, Castello A.
    Ref: bioRxiv
  20. The coronavirus disease (COVID-19) pandemic, caused by the coronavirus SARS-CoV-2, has caused 60 millions of infections and 1.38 millions of fatalities. Genomic analysis of SARS-CoV-2 can provide insights on drug design and vaccine development for controlling the pandemic. Inverted repeats in a genome greatly impact the stability of the genome structure and regulate gene expression. Inverted repeats involve cellular evolution and genetic diversity, genome arrangements, and diseases. Here, we investigate the inverted repeats in the coronavirus SARS-CoV-2 genome. We found that SARS-CoV-2 genome has an abundance of inverted repeats. The inverted repeats are mainly located in the gene of the Spike protein. This result suggests the Spike protein gene undergoes recombination events, therefore, is essential for fast evolution. Comparison of the inverted repeat signatures in human and bat coronaviruses suggest that SARS-CoV-2 is mostly related SARS-related coronavirus, SARSr-CoV/RaTG13. The study also reveals that the recent SARS-related coronavirus, SARSr-CoV/RmYN02, has a high amount of inverted repeats in the spike protein gene. Besides, this study demonstrates that the inverted repeat distribution in a genome can be considered as the genomic signature. This study highlights the significance of inverted repeats in the evolution of SARS-CoV-2 and presents the inverted repeats as the genomic signature in genome analysis.
    Date: 2020-11-24
    Authors: Yin C, Yau SS-.
    Ref: arXiv
  21. Background: Fecal shedding of SARS-CoV-2 has raised concerns about transmission through fecal microbiota transplantation (FMT) procedures. While many tests have been authorized for diagnosis of COVID-19 using respiratory samples, no fully validated stool tests for detection of SARS-CoV-2 are currently available. We sought to adapt and validate an available test specifically for detection of SARS-CoV-2 in human stool. Methods: Stool samples were spiked with inactivated SAR-CoV-2 virus for development and validation of the assay. A modified version of the CDC rRT-PCR SARS-CoV-2 test was used for detection of virus. Analytical sensitivity, assay reproducibility, and sample stability under a variety of storage conditions were assessed. We also performed the assay on stool samples collected from known COVID positive individuals. Findings: The lower limit of detection (LoD) of the assay was found to be 3000 viral RNA copies per gram of original stool sample, with 100% detection across 20 replicates assessed at this concentration. Samples were relatively stable in all buffers tested at both 4 o C and ambient temperature, with the exception of storage in STAR buffer at ambient temperature. Assay sensitivity was slightly diminished in low-copy-number samples after a single freeze-thaw cycle at -80°C. Thirty contrived SARS-CoV-2 samples were tested by a second laboratory and were correctly identified as positive or negative in at least one of two rounds of testing. Additionally, we detected SARS-CoV-2 RNA in the stool of known COVID-19 positive individuals using this method. Interpretation: This is a sensitive, reproducible, and validated assay for detection of SARS-CoV-2 RNA in human stool with potential uses in FMT donor screening, sewage monitoring, and further research into the impact of fecal shedding on the epidemiology of this pandemic. Funding: National Institute for Allergy and Infectious Diseases, NIH. Center for Biologics Evaluation and Research, FDA. Declaration of Interests: None to declare.
    Date: 2020-11-23
    Authors: Michael C, Iakiviak M, Pereira N, Murugkar P, Rippe J, Williams DB, Hastie J, Sava R, Lien C, Wang TT, Muller WJ, Fischbach MA, Carlson PE.
    Ref: SSRN
  22. Quantifying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in clinical samples is crucial for assessing the infectivity of coronavirus disease 2019 and the efficacy of antiviral drugs. Here, we describe a digital warm-start CRISPR (WS-CRISPR) assay for sensitive quantitative detection of SARS-CoV-2 in clinical samples. The WS-CRISPR assay combines low-temperature reverse transcription dual-priming mediated isothermal amplification (RT-DAMP) and CRISPR-Cas12a-based detection in one-pot, attributed to the mediation role by pyrophosphatase and phosphorothioated primers. The WS-CRISPR assay is initiated at above 50 °C and overcomes undesired premature target amplification at room temperature, enabling accurate digital nucleic acid quantification. By targeting SARS-CoV-2’s nucleoprotein gene, digital WS-CRISPR assay is able to detect down to 5 copies/μl SARS-CoV-2 RNA in the chip within 90 minutes. It is clinically validated by quantitatively determining 32 clinical swab samples and three clinical saliva samples, showing 100% agreement with RT-PCR results. Moreover, the digital WS-CRISPR assay has been demonstrated to directly detect SARS-CoV-2 in heat-treated saliva samples without RNA extraction, showing high tolerance to inhibitors. Thus, the digital WS-CRISPR method, as a sensitive and reliable CRISPR assay, facilitates accurate SARS-CoV-2 detection toward digitized quantification.
    Date: 2020-11-23
    Authors: Ding X, Yin K, Li Z, Sfeir MM, Liu C.
    Ref: medRxiv
  23. A bstract The determination of the infection fatality rate (IFR) for the novel SARS-CoV-2 coronavirus is a key aim for many of the field studies that are currently being undertaken in response to the pandemic. The IFR together with the basic reproduction number R 0 , are the main epidemic parameters describing severity and transmissibility of the virus, respectively. The IFR can be also used as a basis for estimating and monitoring the number of infected individuals in a population, which may be subsequently used to inform policy decisions relating to public health interventions and lockdown strategies. The interpretation of IFR measurements requires the calculation of confidence intervals. We present a number of statistical methods that are relevant in this context and develop an inverse problem formulation to determine correction factors to mitigate time-dependent effects that can lead to biased IFR estimates. We also review a number of methods to combine IFR estimates from multiple independent studies, provide example calculations throughout this note and conclude with a summary and “best practice” recommendations. The developed code is available online.
    Date: 2020-11-22
    Authors: Mieskolainen M, Bainbridge R, Buchmueller O, Lyons L, Wardle N.
    Ref: medRxiv
  24. Summary RIG-I, a cytoplasmic viral RNA sensor, is crucial for innate antiviral immune responses; however, there are controversies about RIG-I’s regulatory mechanism by several ubiquitin ligases and LGP2. Our genetic study revealed that the RIPLET ubiquitin ligase was a general activating factor for RIG-I signaling, whereas another ubiquitin ligase, TRIM25, activated RIG-I in a cell-type-specific manner. These RIPLET and TRIM25 functions were modulated by accessory factors, such as ZCCH3C and NLRP12. Interestingly, we found an additional role of RIPLET in innate immune responses. RIPLET induced delayed polyubiquitination of LGP, resulting in the attenuation of excessive cytokine expression at the late phase. Moreover, RIPLET was involved in the innate immune responses against SARS-CoV-2 infection, a cause of the recent COVID-19 pandemic. Our data indicate that RIPLET fine-tunes innate immune responses via polyubiquitination of RIG-I and LGP2 against virus infection, including SARS-CoV-2.
    Date: 2021-01-25
    Authors: Kouwaki T, Nishimura T, Wang G, Nakagawa R, Oshiumi H.
    Ref: bioRxiv
  25. ABSTRACT Mutation-driven evolution of SARS coronavirus-2 (SARS-CoV-2) highlights the need for innovative approaches that simultaneously suppress viral replication and circumvent viral escape routes from host immunity and antiviral therapeutics. Here, we employed genome-wide computational prediction and singlenucleotide resolution screening to reprogram CRISPR-Cas13b against SARS-CoV-2 genomic and subgenomic RNAs. Reprogrammed Cas13b effectors targeting accessible regions of Spike and Nucleocapsid transcripts achieved >98% silencing efficiency in virus free-models. Further, optimized and multiplexed gRNAs suppressed viral replication by up to 90% in mammalian cells infected with replication-competent SARS-CoV-2. Unexpectedly, the comprehensive mutagenesis of guide-target interaction demonstrated that single-nucleotide mismatches do not impair the capacity of a potent single gRNA to simultaneously suppress ancestral and mutated SARS-CoV-2 in infected mammalian cells, including the highly infectious and globally disseminated Spike D614G mutant. The specificity, efficiency and rapid deployment properties of reprogrammed Cas13b described here provide a molecular blueprint of antiviral therapeutics to simultaneously suppress a wide range of SARS-CoV-2 mutants, and is readily adaptable to other emerging pathogenic viruses.
    Date: 2020-11-19
    Authors: Fareh M, Zhao W, Hu W, Casan JM, Kumar A, Symons J, Voskoboinik I, Ekert PG, Rudraraju R, Lewin SR, Trapani JA.
    Ref: bioRxiv
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