Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 20 de 30
Filter
1.
Proc Natl Acad Sci U S A ; 119(15): e2120913119, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1758464

ABSTRACT

SignificanceThe coronavirus main protease (Mpro) is required for viral replication. Here, we obtained the extended conformation of the native monomer of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Mpro by trapping it with nanobodies and found that the catalytic domain and the helix domain dissociate, revealing allosteric targets. Another monomeric state is termed compact conformation and is similar to one protomer of the dimeric form. We designed a Nanoluc Binary Techonology (NanoBiT)-based high-throughput allosteric inhibitor assay based on structural conformational change. Our results provide insight into the maturation, dimerization, and catalysis of the coronavirus Mpro and pave a way to develop an anticoronaviral drug through targeting the maturation process to inhibit the autocleavage of Mpro.


Subject(s)
COVID-19 , SARS-CoV-2 , Antiviral Agents/pharmacology , COVID-19/drug therapy , Coronavirus 3C Proteases , Humans , Luciferases , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology
2.
Commun Biol ; 5(1): 212, 2022 03 08.
Article in English | MEDLINE | ID: covidwho-1735294

ABSTRACT

Internalization of membrane proteins plays a key role in many physiological functions; however, highly sensitive and versatile technologies are lacking to study such processes in real-time living systems. Here we describe an assay based on bioluminescence able to quantify membrane receptor trafficking for a wide variety of internalization mechanisms such as GPCR internalization/recycling, antibody-mediated internalization, and SARS-CoV2 viral infection. This study represents an alternative drug discovery tool to accelerate the drug development for a wide range of physiological processes, such as cancer, neurological, cardiopulmonary, metabolic, and infectious diseases including COVID-19.


Subject(s)
Drug Discovery/methods , Membrane Proteins , Protein Transport/physiology , Spectrometry, Fluorescence/methods , COVID-19 , Drug Development/methods , HEK293 Cells , Humans , Luciferases/genetics , Luciferases/metabolism , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Microscopy, Fluorescence , Nanotechnology , Receptors, G-Protein-Coupled , SARS-CoV-2/chemistry , SARS-CoV-2/metabolism , Virus Internalization
3.
Antiviral Res ; 201: 105272, 2022 May.
Article in English | MEDLINE | ID: covidwho-1729532

ABSTRACT

Effective drugs against SARS-CoV-2 are urgently needed to treat severe cases of infection and for prophylactic use. The main viral protease (nsp5 or 3CLpro) represents an attractive and possibly broad-spectrum target for drug development as it is essential to the virus life cycle and highly conserved among betacoronaviruses. Sensitive and efficient high-throughput screening methods are key for drug discovery. Here we report the development of a gain-of-signal, highly sensitive cell-based luciferase assay to monitor SARS-CoV-2 nsp5 activity and show that it is suitable for the screening of compounds in a 384-well format. A benefit of miniaturisation and automation is that screening can be performed in parallel on a wild-type and a catalytically inactive nsp5, which improves the selectivity of the assay. We performed molecular docking-based screening on a set of 14,468 compounds from an in-house chemical database, selected 359 candidate nsp5 inhibitors and tested them experimentally. We identified two molecules which show anti-nsp5 activity, both in our cell-based assay and in vitro on purified nsp5 protein, and inhibit SARS-CoV-2 replication in A549-ACE2 cells with EC50 values in the 4-8 µM range. The here described high-throughput-compatible assay will allow the screening of large-scale compound libraries for SARS-CoV-2 nsp5 inhibitors. Moreover, we provide evidence that this assay can be adapted to other coronaviruses and viruses which rely on a viral protease.


Subject(s)
COVID-19 , SARS-CoV-2 , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , COVID-19/drug therapy , Humans , Luciferases/genetics , Molecular Docking Simulation , Peptide Hydrolases , Protease Inhibitors/pharmacology , Viral Proteases
4.
Int J Mol Sci ; 22(21)2021 Oct 28.
Article in English | MEDLINE | ID: covidwho-1518611

ABSTRACT

Inhaled nebulized interferon (IFN)-α and IFN-ß have been shown to be effective in the management of coronavirus disease 2019 (COVID-19). We aimed to construct a virus-free rapid detection system for high-throughput screening of IFN-like compounds that induce viral RNA degradation and suppress the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We prepared a SARS-CoV-2 subreplicon RNA expression vector which contained the SARS-CoV-2 5'-UTR, the partial sequence of ORF1a, luciferase, nucleocapsid, ORF10, and 3'-UTR under the control of the cytomegalovirus promoter. The expression vector was transfected into Calu-3 cells and treated with IFN-α and the IFNAR2 agonist CDM-3008 (RO8191) for 3 days. SARS-CoV-2 subreplicon RNA degradation was subsequently evaluated based on luciferase levels. IFN-α and CDM-3008 suppressed SARS-CoV-2 subreplicon RNA in a dose-dependent manner, with IC50 values of 193 IU/mL and 2.54 µM, respectively. HeLa cells stably expressing SARS-CoV-2 subreplicon RNA were prepared and treated with the IFN-α and pan-JAK inhibitor Pyridone 6 or siRNA-targeting ISG20. IFN-α activity was canceled with Pyridone 6. The knockdown of ISG20 partially canceled IFN-α activity. Collectively, we constructed a virus-free rapid detection system to measure SARS-CoV-2 RNA suppression. Our data suggest that the SARS-CoV-2 subreplicon RNA was degraded by IFN-α-induced ISG20 exonuclease activity.


Subject(s)
Antiviral Agents/pharmacology , Drug Evaluation, Preclinical/methods , Interferon-alpha/pharmacology , RNA, Viral/metabolism , SARS-CoV-2/genetics , Cell Line, Tumor , Dose-Response Relationship, Drug , Exoribonucleases/genetics , Genetic Vectors , HeLa Cells , Humans , Interferon-alpha/administration & dosage , Luciferases/genetics , Luciferases/metabolism , Naphthyridines/administration & dosage , Naphthyridines/pharmacology , Oxadiazoles/administration & dosage , Oxadiazoles/pharmacology , RNA, Viral/drug effects , Replicon
5.
Int J Mol Sci ; 22(21)2021 Oct 26.
Article in English | MEDLINE | ID: covidwho-1512374

ABSTRACT

Nucleoside kinases (NKs) are key enzymes involved in the in vivo phosphorylation of nucleoside analogues used as drugs to treat cancer or viral infections. Having different specificities, the characterization of NKs is essential for drug design and nucleotide analogue production in an in vitro enzymatic process. Therefore, a fast and reliable substrate screening method for NKs is of great importance. Here, we report on the validation of a well-known luciferase-based assay for the detection of NK activity in a 96-well plate format. The assay was semi-automated using a liquid handling robot. Good linearity was demonstrated (r² > 0.98) in the range of 0-500 µM ATP, and it was shown that alternative phosphate donors like dATP or CTP were also accepted by the luciferase. The developed high-throughput assay revealed comparable results to HPLC analysis. The assay was exemplarily used for the comparison of the substrate spectra of four NKs using 20 (8 natural, 12 modified) substrates. The screening results correlated well with literature data, and additionally, previously unknown substrates were identified for three of the NKs studied. Our results demonstrate that the developed semi-automated high-throughput assay is suitable to identify best performing NKs for a wide range of substrates.


Subject(s)
Nucleosides/metabolism , Phosphotransferases/metabolism , Adenosine Triphosphate/metabolism , Animals , Drosophila melanogaster/metabolism , Drug Evaluation, Preclinical/methods , High-Throughput Screening Assays/methods , Humans , Luciferases/metabolism , Phosphorylation/physiology , Substrate Specificity
6.
Int J Mol Sci ; 22(21)2021 Oct 28.
Article in English | MEDLINE | ID: covidwho-1488612

ABSTRACT

Inhaled nebulized interferon (IFN)-α and IFN-ß have been shown to be effective in the management of coronavirus disease 2019 (COVID-19). We aimed to construct a virus-free rapid detection system for high-throughput screening of IFN-like compounds that induce viral RNA degradation and suppress the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We prepared a SARS-CoV-2 subreplicon RNA expression vector which contained the SARS-CoV-2 5'-UTR, the partial sequence of ORF1a, luciferase, nucleocapsid, ORF10, and 3'-UTR under the control of the cytomegalovirus promoter. The expression vector was transfected into Calu-3 cells and treated with IFN-α and the IFNAR2 agonist CDM-3008 (RO8191) for 3 days. SARS-CoV-2 subreplicon RNA degradation was subsequently evaluated based on luciferase levels. IFN-α and CDM-3008 suppressed SARS-CoV-2 subreplicon RNA in a dose-dependent manner, with IC50 values of 193 IU/mL and 2.54 µM, respectively. HeLa cells stably expressing SARS-CoV-2 subreplicon RNA were prepared and treated with the IFN-α and pan-JAK inhibitor Pyridone 6 or siRNA-targeting ISG20. IFN-α activity was canceled with Pyridone 6. The knockdown of ISG20 partially canceled IFN-α activity. Collectively, we constructed a virus-free rapid detection system to measure SARS-CoV-2 RNA suppression. Our data suggest that the SARS-CoV-2 subreplicon RNA was degraded by IFN-α-induced ISG20 exonuclease activity.


Subject(s)
Antiviral Agents/pharmacology , Drug Evaluation, Preclinical/methods , Interferon-alpha/pharmacology , RNA, Viral/metabolism , SARS-CoV-2/genetics , Cell Line, Tumor , Dose-Response Relationship, Drug , Exoribonucleases/genetics , Genetic Vectors , HeLa Cells , Humans , Interferon-alpha/administration & dosage , Luciferases/genetics , Luciferases/metabolism , Naphthyridines/administration & dosage , Naphthyridines/pharmacology , Oxadiazoles/administration & dosage , Oxadiazoles/pharmacology , RNA, Viral/drug effects , Replicon
7.
Viruses ; 13(10)2021 10 04.
Article in English | MEDLINE | ID: covidwho-1463827

ABSTRACT

Porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus, causes diarrhoea in suckling piglets and has the potential for cross-species transmission. No effective PDCoV vaccines or antiviral drugs are currently available. Here, we successfully generated an infectious clone of PDCoV strain CHN-HN-2014 using a combination of bacterial artificial chromosome (BAC)-based reverse genetics system with a one-step homologous recombination. The recued virus (rCHN-HN-2014) possesses similar growth characteristics to the parental virus in vitro. Based on the established infectious clone and CRISPR/Cas9 technology, a PDCoV reporter virus expressing nanoluciferase (Nluc) was constructed by replacing the NS6 gene. Using two drugs, lycorine and resveratrol, we found that the Nluc reporter virus exhibited high sensibility and easy quantification to rapid antiviral screening. We further used the Nluc reporter virus to test the susceptibility of different cell lines to PDCoV and found that cell lines derived from various host species, including human, swine, cattle and monkey enables PDCoV replication, broadening our understanding of the PDCoV cell tropism range. Taken together, our reporter viruses are available to high throughput screening for antiviral drugs and uncover the infectivity of PDCoV in various cells, which will accelerate our understanding of PDCoV.


Subject(s)
Coronavirus Infections/veterinary , Deltacoronavirus/genetics , Deltacoronavirus/metabolism , Genes, Reporter/genetics , Luciferases/genetics , A549 Cells , Animals , Cell Line , Chlorocebus aethiops , Chromosomes, Artificial, Bacterial/genetics , Coronavirus Infections/pathology , Deltacoronavirus/growth & development , Dogs , Genome, Viral/genetics , Humans , Luciferases/biosynthesis , Madin Darby Canine Kidney Cells , Nanostructures , Swine , Swine Diseases/virology , Vero Cells , Virus Replication/genetics
8.
N Biotechnol ; 66: 53-60, 2022 Jan 25.
Article in English | MEDLINE | ID: covidwho-1433688

ABSTRACT

The COVID-19 pandemic has illustrated the global demand for rapid, low-cost, widely distributable and point-of-care nucleic acid diagnostic technologies. Such technologies could help disrupt transmission, sustain economies and preserve health and lives during widespread infection. In contrast, conventional nucleic acid diagnostic procedures require trained personnel, complex laboratories, expensive equipment, and protracted processing times. In this work, lyophilized cell-free protein synthesis (CFPS) and toehold switch riboregulators are employed to develop a promising paper-based nucleic acid diagnostic platform activated simply by the addition of saliva. First, to facilitate distribution and deployment, an economical paper support matrix is identified and a mass-producible test cassette designed with integral saliva sample receptacles. Next, CFPS is optimized in the presence of saliva using murine RNase inhibitor. Finally, original toehold switch riboregulators are engineered to express the bioluminescent reporter NanoLuc in response to SARS-CoV-2 RNA sequences present in saliva samples. The biosensor generates a visible signal in as few as seven minutes following administration of 15 µL saliva enriched with high concentrations of SARS-CoV-2 RNA sequences. The estimated cost of this test is less than 0.50 USD, which could make this platform readily accessible to both the developed and developing world. While additional research is needed to decrease the limit of detection, this work represents important progress toward developing a diagnostic technology that is rapid, low-cost, distributable and deployable at the point-of-care by a layperson.


Subject(s)
Biosensing Techniques , COVID-19 , Luminescent Measurements , RNA, Viral/isolation & purification , Saliva/chemistry , COVID-19/diagnosis , Humans , Luciferases , SARS-CoV-2
9.
Sci Rep ; 11(1): 18428, 2021 09 16.
Article in English | MEDLINE | ID: covidwho-1415954

ABSTRACT

Here we describe a homogeneous bioluminescent immunoassay based on the interaction between Fc-tagged SARS-CoV-2 Spike RBD and human ACE2, and its detection by secondary antibodies labeled with NanoLuc luciferase fragments LgBit and SmBit. The assay utility for the discovery of novel inhibitors was demonstrated with a panel of anti-RBD antibodies, ACE2-derived miniproteins and soluble ACE2. Studying the effect of RBD mutations on ACE2 binding showed that the N501Y mutation increased RBD apparent affinity toward ACE2 tenfold that resulted in escaping inhibition by some anti-RBD antibodies. In contrast, while E484K mutation did not highly change the binding affinity, it still escaped antibody inhibition likely due to changes in the epitope recognized by the antibody. Also, neutralizing antibodies (NAbs) from COVID-19 positive samples from two distinct regions (USA and Brazil) were successfully detected and the results further suggest the persistence of NAbs for at least 6 months post symptom onset. Finally, sera from vaccinated individuals were tested for NAbs and showed varying neutralizing activity after first and second doses, suggesting the assay can be used to assess immunity of vaccinated populations. Our results demonstrate the broad utility and ease of use of this methodology both for drug discovery and clinical research applications.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Neutralizing/analysis , COVID-19/prevention & control , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Antibodies, Viral/analysis , Brazil , COVID-19/immunology , Humans , Luciferases/genetics , Luciferases/metabolism , Luminescent Measurements , Mutation , Protein Binding , Protein Domains , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/genetics , United States , Vaccination
10.
PLoS Pathog ; 17(9): e1009840, 2021 09.
Article in English | MEDLINE | ID: covidwho-1403328

ABSTRACT

COVID-19 vaccines based on the Spike protein of SARS-CoV-2 have been developed that appear to be largely successful in stopping infection. However, therapeutics that can help manage the disease are still required until immunity has been achieved globally. The identification of repurposed drugs that stop SARS-CoV-2 replication could have enormous utility in stemming the disease. Here, using a nano-luciferase tagged version of the virus (SARS-CoV-2-ΔOrf7a-NLuc) to quantitate viral load, we evaluated a range of human cell types for their ability to be infected and support replication of the virus, and performed a screen of 1971 FDA-approved drugs. Hepatocytes, kidney glomerulus, and proximal tubule cells were particularly effective in supporting SARS-CoV-2 replication, which is in-line with reported proteinuria and liver damage in patients with COVID-19. Using the nano-luciferase as a measure of virus replication we identified 35 drugs that reduced replication in Vero cells and human hepatocytes when treated prior to SARS-CoV-2 infection and found amodiaquine, atovaquone, bedaquiline, ebastine, LY2835219, manidipine, panobinostat, and vitamin D3 to be effective in slowing SARS-CoV-2 replication in human cells when used to treat infected cells. In conclusion, our study has identified strong candidates for drug repurposing, which could prove powerful additions to the treatment of COVID.


Subject(s)
COVID-19/drug therapy , Drug Discovery/methods , Drug Repositioning , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Animals , Biomarkers , Cell Line , Chlorocebus aethiops , Hepatocytes/virology , Humans , Luciferases/pharmacology , Nanostructures , SARS-CoV-2/genetics , Vero Cells , Virus Replication/drug effects
11.
Nat Commun ; 12(1): 4586, 2021 07 28.
Article in English | MEDLINE | ID: covidwho-1387355

ABSTRACT

Heterogeneous immunoassays such as ELISA have become indispensable in modern bioanalysis, yet translation into point-of-care assays is hindered by their dependence on external calibration and multiple washing and incubation steps. Here, we introduce RAPPID (Ratiometric Plug-and-Play Immunodiagnostics), a mix-and-measure homogeneous immunoassay platform that combines highly specific antibody-based detection with a ratiometric bioluminescent readout. The concept entails analyte-induced complementation of split NanoLuc luciferase fragments, photoconjugated to an antibody sandwich pair via protein G adapters. Introduction of a calibrator luciferase provides a robust ratiometric signal that allows direct in-sample calibration and quantitative measurements in complex media such as blood plasma. We developed RAPPID sensors that allow low-picomolar detection of several protein biomarkers, anti-drug antibodies, therapeutic antibodies, and both SARS-CoV-2 spike protein and anti-SARS-CoV-2 antibodies. With its easy-to-implement standardized workflow, RAPPID provides an attractive, fast, and low-cost alternative to traditional immunoassays, in an academic setting, in clinical laboratories, and for point-of-care applications.


Subject(s)
Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Immunoassay/standards , Luminescent Measurements/standards , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/blood , COVID-19/immunology , COVID-19/virology , COVID-19 Serological Testing/instrumentation , Calibration , GTP-Binding Proteins/chemistry , Genes, Reporter , Humans , Immunoconjugates/chemistry , Limit of Detection , Luciferases/genetics , Luciferases/metabolism , Point-of-Care Testing , SARS-CoV-2/genetics
12.
Immunity ; 54(9): 2143-2158.e15, 2021 09 14.
Article in English | MEDLINE | ID: covidwho-1364125

ABSTRACT

Neutralizing antibodies (NAbs) are effective in treating COVID-19, but the mechanism of immune protection is not fully understood. Here, we applied live bioluminescence imaging (BLI) to monitor the real-time effects of NAb treatment during prophylaxis and therapy of K18-hACE2 mice intranasally infected with SARS-CoV-2-nanoluciferase. Real-time imaging revealed that the virus spread sequentially from the nasal cavity to the lungs in mice and thereafter systemically to various organs including the brain, culminating in death. Highly potent NAbs from a COVID-19 convalescent subject prevented, and also effectively resolved, established infection when administered within three days. In addition to direct neutralization, depletion studies indicated that Fc effector interactions of NAbs with monocytes, neutrophils, and natural killer cells were required to effectively dampen inflammatory responses and limit immunopathology. Our study highlights that both Fab and Fc effector functions of NAbs are essential for optimal in vivo efficacy against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/metabolism , Antibodies, Viral/metabolism , Brain/pathology , COVID-19/immunology , Lung/pathology , SARS-CoV-2/physiology , Testis/pathology , Angiotensin-Converting Enzyme 2/genetics , Animals , Antibodies, Neutralizing/genetics , Antibodies, Viral/genetics , Brain/virology , COVID-19/therapy , Cells, Cultured , Disease Models, Animal , Humans , Immunoglobulin Fc Fragments/genetics , Luciferases/genetics , Luminescent Measurements , Lung/virology , Male , Mice , Mice, Transgenic , Testis/virology
13.
STAR Protoc ; 2(4): 100781, 2021 12 17.
Article in English | MEDLINE | ID: covidwho-1356489

ABSTRACT

We present a protocol for analyzing the impact of SARS-CoV-2 proteins in interferon signaling using luciferase reporter assays. Here, the induction of defined promoters can be quantitatively assessed with high sensitivity and broad linear range. The results are similar to those obtained using qPCR to measure endogenous mRNA induction. The assay requires stringent normalization and confirmation of the results in more physiological settings. The protocol is adaptable for other viruses and other innate immune stimuli. For complete details on the use and execution of this protocol, please refer to Hayn et al. (2021).


Subject(s)
COVID-19/pathology , Gene Expression Regulation, Viral/drug effects , Interferons/pharmacology , Luciferases/metabolism , RNA, Messenger/metabolism , SARS-CoV-2/metabolism , Viral Proteins/metabolism , Antiviral Agents/pharmacology , COVID-19/drug therapy , COVID-19/metabolism , COVID-19/virology , Humans , Luciferases/genetics , Promoter Regions, Genetic , RNA, Messenger/genetics , SARS-CoV-2/drug effects , Viral Proteins/genetics
14.
Sci Rep ; 11(1): 9136, 2021 04 28.
Article in English | MEDLINE | ID: covidwho-1207152

ABSTRACT

Coiled-coil (CC) dimer-forming peptides are attractive designable modules for mediating protein association. Highly stable CCs are desired for biological activity regulation and assay. Here, we report the design and versatile applications of orthogonal CC dimer-forming peptides with a dissociation constant in the low nanomolar range. In vitro stability and specificity was confirmed in mammalian cells by enzyme reconstitution, transcriptional activation using a combination of DNA-binding and a transcriptional activation domain, and cellular-enzyme-activity regulation based on externally-added peptides. In addition to cellular regulation, coiled-coil-mediated reporter reconstitution was used for the detection of cell fusion mediated by the interaction between the spike protein of pandemic SARS-CoV2 and the ACE2 receptor. This assay can be used to investigate the mechanism of viral spike protein-mediated fusion or screening for viral inhibitors under biosafety level 1 conditions.


Subject(s)
Host-Pathogen Interactions/physiology , Peptides/chemistry , Peptides/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Cell Fusion , Circular Dichroism , Giant Cells/virology , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HEK293 Cells , Humans , Luciferases/genetics , Luciferases/metabolism , Membrane Fusion , Peptides/genetics , Protein Engineering/methods , Protein Multimerization , Protein Stability , Serine Endopeptidases/genetics , Serine Endopeptidases/metabolism , Transcription, Genetic
15.
J Mol Biol ; 433(13): 166983, 2021 06 25.
Article in English | MEDLINE | ID: covidwho-1174385

ABSTRACT

Recombinant antibodies (Abs) against the SARS-CoV-2 virus hold promise for treatment of COVID-19 and high sensitivity and specific diagnostic assays. Here, we report engineering principles and realization of a Protein-fragment Complementation Assay (PCA) detector of SARS-CoV-2 antigen by coupling two Abs to complementary N- and C-terminal fragments of the reporter enzyme Gaussia luciferase (Gluc). Both Abs display comparably high affinities for distinct epitopes of viral Spike (S)-protein trimers. Gluc activity is reconstituted when the Abs are simultaneously bound to S-protein bringing the Ab-fused N- and C-terminal fragments close enough together (8 nm) to fold. We thus achieve high specificity both by requirement of simultaneous binding of the two Abs to the S-protein and also, in a steric configuration in which the two Gluc complementary fragments can fold and thus reconstitute catalytic activity. Gluc activity can also be reconstituted with virus-like particles that express surface S-protein with detectable signal over background within 5 min of incubation. Design principles presented here can be readily applied to develop reporters to virtually any protein with sufficient available structural details. Thus, our results present a general framework to develop reporter assays for COVID-19, and the strategy can be readily deployed in response to existing and future pathogenic threats and other diseases.


Subject(s)
Antibodies, Viral/chemistry , Antigens, Viral/immunology , COVID-19/diagnosis , COVID-19/virology , SARS-CoV-2/isolation & purification , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/genetics , Antibodies, Viral/immunology , Antigens, Viral/chemistry , Antigens, Viral/isolation & purification , Epitopes/immunology , Humans , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Luciferases , Luminescent Measurements/methods , Protein Engineering , SARS-CoV-2/chemistry , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology
16.
Nat Commun ; 12(1): 1806, 2021 03 22.
Article in English | MEDLINE | ID: covidwho-1146643

ABSTRACT

Better diagnostic tools are needed to combat the ongoing COVID-19 pandemic. Here, to meet this urgent demand, we report a homogeneous immunoassay to detect IgG antibodies against SARS-CoV-2. This serological assay, called SATiN, is based on a tri-part Nanoluciferase (tNLuc) approach, in which the spike protein of SARS-CoV-2 and protein G, fused respectively to two different tNLuc tags, are used as antibody probes. Target engagement of the probes allows reconstitution of a functional luciferase in the presence of the third tNLuc component. The assay is performed directly in the liquid phase of patient sera and enables rapid, quantitative and low-cost detection. We show that SATiN has a similar sensitivity to ELISA, and its readouts are consistent with various neutralizing antibody assays. This proof-of-principle study suggests potential applications in diagnostics, as well as disease and vaccination management.


Subject(s)
Antibodies, Viral/blood , COVID-19 Testing/methods , COVID-19/diagnosis , Immunoassay/methods , Luciferases/metabolism , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Antibodies, Neutralizing/blood , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/virology , Enzyme-Linked Immunosorbent Assay , HEK293 Cells , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , Spike Glycoprotein, Coronavirus/immunology
17.
J Virol Methods ; 292: 114141, 2021 06.
Article in English | MEDLINE | ID: covidwho-1142107

ABSTRACT

In this study, we developed and evaluated a luciferase immunosorbent assay (LISA) for quantitative detection of IgG antibody against SARS-CoV-2 nucleoprotein (NP). Anti-SARS-CoV-2 NP antibody in serum or plasma samples was captured by protein G-coated microtiter plate and detected using the crude cell lysates expressing Nanoluc luciferase (Nluc) enzyme fused with SARS-CoV-2 NP. After the addition of furimazine substrate, the levels of anti-SARS-CoV-2 NP IgG antibody were quantitatively measured as luciferase light units. As expected, SARS-CoV-2 NP showed cross-reactivity with the monoclonal antibodies against SARS-CoV NP, but not MERS-CoV NP-specific monoclonal antibodies or the monoclonal antibodies against SARS-CoV Spike protein. LISA for detecting murine monoclonal antibody against SARS-CoV NP showed a low limit of detection of 0.4 pg/µl and linear detection range from 0.4 pg/µl to 75 pg/µl. Furthermore, LISA had a sensitivity of 71 % when testing COVID-19 patients at the second week post onset and a specificity of 100 % when testing healthy blood donors.


Subject(s)
Antibodies, Viral/blood , COVID-19/diagnosis , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin G/blood , Nucleocapsid Proteins/immunology , SARS-CoV-2/immunology , Antibodies, Monoclonal/immunology , Cross Reactions , Humans , Luciferases
18.
Biosens Bioelectron ; 180: 113122, 2021 May 15.
Article in English | MEDLINE | ID: covidwho-1116328

ABSTRACT

As the COVID-19 pandemic continues, there is an imminent need for rapid diagnostic tools and effective antivirals targeting SARS-CoV-2. We have developed a novel bioluminescence-based biosensor to probe a key host-virus interaction during viral entry: the binding of SARS-CoV-2 viral spike (S) protein to its receptor, angiotensin-converting enzyme 2 (ACE2). Derived from Nanoluciferase binary technology (NanoBiT), the biosensor is composed of Nanoluciferase split into two complementary subunits, Large BiT and Small BiT, fused to the Spike S1 domain of the SARS-CoV-2 S protein and ACE2 ectodomain, respectively. The ACE2-S1 interaction results in reassembly of functional Nanoluciferase, which catalyzes a bioluminescent reaction that can be assayed in a highly sensitive and specific manner. We demonstrate the biosensor's large dynamic range, enhanced thermostability and pH tolerance. In addition, we show the biosensor's versatility towards the high-throughput screening of drugs which disrupt the ACE2-S1 interaction, as well as its ability to act as a surrogate virus neutralization assay. Results obtained with our biosensor correlate well with those obtained with a Spike-pseudotyped lentivirus assay. This rapid in vitro tool does not require infectious virus and should enable the timely development of antiviral modalities targeting SARS-CoV-2 entry.


Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , Biosensing Techniques/methods , COVID-19/diagnosis , Luminescent Measurements/methods , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , HEK293 Cells , Humans , Luciferases , Neutralization Tests , Virus Internalization
19.
Mol Ther ; 29(6): 1984-2000, 2021 06 02.
Article in English | MEDLINE | ID: covidwho-1093250

ABSTRACT

The ongoing COVID-19 pandemic has highlighted the immediate need for the development of antiviral therapeutics targeting different stages of the SARS-CoV-2 life cycle. We developed a bioluminescence-based bioreporter to interrogate the interaction between the SARS-CoV-2 viral spike (S) protein and its host entry receptor, angiotensin-converting enzyme 2 (ACE2). The bioreporter assay is based on a nanoluciferase complementation reporter, composed of two subunits, large BiT and small BiT, fused to the S receptor-binding domain (RBD) of the SARS-CoV-2 S protein and ACE2 ectodomain, respectively. Using this bioreporter, we uncovered critical host and viral determinants of the interaction, including a role for glycosylation of asparagine residues within the RBD in mediating successful viral entry. We also demonstrate the importance of N-linked glycosylation to the RBD's antigenicity and immunogenicity. Our study demonstrates the versatility of our bioreporter in mapping key residues mediating viral entry as well as screening inhibitors of the ACE2-RBD interaction. Our findings point toward targeting RBD glycosylation for therapeutic and vaccine strategies against SARS-CoV-2.


Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , Antibodies, Neutralizing/pharmacology , Biological Assay , Lectins/pharmacology , Receptors, Virus/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/immunology , Asparagine/chemistry , Asparagine/metabolism , Binding Sites , COVID-19/diagnosis , COVID-19/drug therapy , COVID-19/immunology , COVID-19/virology , Genes, Reporter , Glycosylation/drug effects , HEK293 Cells , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Humans , Luciferases/genetics , Luciferases/metabolism , Luminescent Measurements , Protein Binding , Protein Interaction Domains and Motifs , Protein Structure, Secondary , Receptors, Virus/antagonists & inhibitors , Receptors, Virus/genetics , Receptors, Virus/immunology , SARS-CoV-2/drug effects , SARS-CoV-2/growth & development , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Virus Internalization/drug effects
20.
Viruses ; 13(2)2021 01 24.
Article in English | MEDLINE | ID: covidwho-1052508

ABSTRACT

The 3C-like protease (3CLpro) of SARS-CoV-2 is considered an excellent target for COVID-19 antiviral drug development because it is essential for viral replication and has a cleavage specificity distinct from human proteases. However, drug development for 3CLpro has been hindered by a lack of cell-based reporter assays that can be performed in a BSL-2 setting. Current efforts to identify 3CLpro inhibitors largely rely upon in vitro screening, which fails to account for cell permeability and cytotoxicity of compounds, or assays involving replication-competent virus, which must be performed in a BSL-3 facility. To address these limitations, we have developed a novel cell-based luciferase complementation reporter assay to identify inhibitors of SARS-CoV-2 3CLpro in a BSL-2 setting. The assay is based on a lentiviral vector that co-expresses 3CLpro and two luciferase fragments linked together by a 3CLpro cleavage site. 3CLpro-mediated cleavage results in a loss of complementation and low luciferase activity, whereas inhibition of 3CLpro results in 10-fold higher levels of luciferase activity. The luciferase reporter assay can easily distinguish true 3CLpro inhibition from cytotoxicity, a powerful feature that should reduce false positives during screening. Using the assay, we screened 32 small molecules for activity against SARS-CoV-2 3CLpro, including HIV protease inhibitors, HCV protease inhibitors, and various other compounds that have been reported to inhibit SARS-CoV-2 3CLpro. Of these, only five exhibited significant inhibition of 3CLpro in cells: GC376, boceprevir, Z-FA-FMK, calpain inhibitor XII, and GRL-0496. This assay should greatly facilitate efforts to identify more potent inhibitors of SARS-CoV-2 3CLpro.


Subject(s)
Antiviral Agents/metabolism , Coronavirus 3C Proteases/antagonists & inhibitors , Luciferases/metabolism , Protease Inhibitors/metabolism , SARS-CoV-2/enzymology , Antiviral Agents/pharmacology , Cell Survival/drug effects , Coronavirus 3C Proteases/genetics , Coronavirus 3C Proteases/metabolism , Drug Evaluation, Preclinical , HEK293 Cells , Humans , Lentivirus/genetics , Luciferases/genetics , Protease Inhibitors/pharmacology
SELECTION OF CITATIONS
SEARCH DETAIL