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1.
Anal Chem ; 93(42): 14238-14246, 2021 10 26.
Article in English | MEDLINE | ID: covidwho-1461947

ABSTRACT

Direct detection of SARS-CoV-2 in biological specimens is often challenging due to the low abundance of viral components and lack of enough sensitivity. Herein, we developed a new type of chemiluminescent functionalized magnetic nanomaterial for sensitive detection of the SARS-CoV-2 antigen. First, HAuCl4 was reduced by N-(aminobutyl)-N-(ethylisoluminol) (ABEI) in the presence of amino magnetic beads (MB-NH2) to generate ABEI-AuNPs, which were directly assembled on the surface of MB-NH2. Then, Co2+ was modified onto the surface to form MB@ABEI-Au/Co2+ (MAA/Co2+). MAA/Co2+ exhibited good chemiluminescence (CL) and magnetic properties. It was also found that it was easy for the antibody to be connected with MAA/Co2+. Accordingly, MAA/Co2+ was used as a sensing interface to construct a label-free immunoassay for rapid detection of the N protein in SARS-CoV-2. The immunoassay showed a linear range from 0.1 pg/mL to 10 ng/mL and a low detection limit of 69 fg/mL, which was superior to previously reported methods for N protein detection. It also demonstrated good selectivity by virtue of magnetic separation, which effectively removed a sample matrix after immunoreactions. It was successfully applied for the detection of the N protein in spiked human serum and saliva samples. Furthermore, the immunoassay was integrated with an automatic CL analyzer with magnetic separation to detect the N protein in patient serums and rehabilitation patient serums with satisfactory results. Thus, the CL immunoassay without a complicated labeling procedure is sensitive, selective, fast, simple, and cost-effective, which may be used to combat the COVID-19 pandemic. Finally, the CL quenching mechanism of the N protein in the immunoassay was also explored.


Subject(s)
COVID-19 , Metal Nanoparticles , Gold , Humans , Immunoassay , Limit of Detection , Luminescence , Luminescent Measurements , Pandemics , SARS-CoV-2
2.
Life Sci Alliance ; 4(12)2021 12.
Article in English | MEDLINE | ID: covidwho-1449494

ABSTRACT

The continued resurgence of the COVID-19 pandemic with multiple variants underlines the need for diagnostics that are adaptable to the virus. We have developed toehold RNA-based sensors across the SARS-CoV-2 genome for direct and ultrasensitive detection of the virus and its prominent variants. Here, 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, for example, 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 that is capable of detecting as low as 100 copies of viral RNA with development of bright color. This is easily visualized by the human eye and quantifiable using spectrophotometry. Finally, this PHAsed NASBA-Translation Optical Method (PHANTOM) using our engineered RNA biosensors efficiently detects viral RNA in patient samples. This work presents a powerful and universally accessible strategy for detecting COVID-19 and variants. This strategy is adaptable to further viral evolution and brings RNA bioengineering center-stage.


Subject(s)
COVID-19/virology , RNA, Viral/analysis , SARS-CoV-2/isolation & purification , Biosensing Techniques , COVID-19/diagnosis , Humans , Luminescence , Nucleic Acid Amplification Techniques/methods , RNA/genetics , RNA, Viral/genetics , SARS-CoV-2/genetics
3.
J Virol Methods ; 298: 114299, 2021 12.
Article in English | MEDLINE | ID: covidwho-1433623

ABSTRACT

Real-time reverse transcription- polymerase chain reaction (RT-PCR) has been the most reliable armoury for the diagnosis of COVID-19, considered to be the reference standard but fails to reproduce the correct predictability about the infectivity of the disease every time. Antigen detection however puts foothold in this aspect even though lacks in sensitivity, especially conventional Rapid Antigen Tests (RATs). Recently developed Chemiluminescence Immunoassay (CLIA) based antigen detection tests are promising and displayed better sensitivity. In the current study we have evaluated VITROS® SARS-CoV-2 Ag Test CLIA Kit, which was tested on 148 patient's samples attended to a tertiary care centre for testing of SARS-CoV-2. The performance of the kit was evaluated in comparison to RT-PCR and RAT and found to be a good test for antigen detection, best within the first few days of infection. The test has shown sensitivity of 94.3 % and specificity of 100 % in samples with corresponding Ct values of ≤25 by RT-PCR, which corresponds to high viral load and can predict ability of spreading the disease by the patients. With the results being semiquantitative along with improved sensitivity it can replace RATs for antigen detection for screening, provided good laboratory set up is included under consideration.


Subject(s)
COVID-19 , Humans , Immunoassay , Luminescence , SARS-CoV-2 , Sensitivity and Specificity
5.
Int J Mol Sci ; 22(8)2021 Apr 14.
Article in English | MEDLINE | ID: covidwho-1299443

ABSTRACT

Photodegradation of the aqueous solutions of acetylsalicylic acid, in the absence (ASA) and the presence of excipients (ASE), is demonstrated by the photoluminescence (PL). A shift of the PL bands from 342 and 338 nm to 358 and 361-397 nm for ASA and ASE in solid state and as aqueous solutions was reported. By exposure of the solution of ASA 0.3 M to UV light, a decrease in the PL band intensity was highlighted. This behavior was revealed for ASA in the presence of phosphate buffer (PB) having the pH equal to 6.4, 7, and 8 or by the interaction with NaOH 0.3 M. A different behavior was reported in the case of ASE. In the presence of PB, an increase in the intensity of the PL band of ASE simultaneously with a change of the ratio between the intensities of the bands at 361-364 and 394-397 nm was highlighted. The differences between PL spectra of ASA and ASE have their origin in the presence of salicylic acid (SAL). The interaction of ASE with NaOH induces a shift of the PL band at 405-407 nm. Arguments for the reaction of ASA with NaOH are shown by Raman scattering and FTIR spectroscopy.


Subject(s)
Aspirin/chemistry , Photolysis/radiation effects , Solutions/radiation effects , Water/chemistry , Aspirin/radiation effects , Cadmium Compounds/chemistry , Luminescence , Quantum Dots/chemistry , Spectrum Analysis, Raman , Ultraviolet Rays/adverse effects
6.
Anal Chem ; 93(28): 9933-9938, 2021 07 20.
Article in English | MEDLINE | ID: covidwho-1297285

ABSTRACT

Sensitive detection of the SARS-CoV-2 protein remains a great research interest in clinical screening and diagnosis owing to the coronavirus epidemic. Here, an ultrasensitive chemiluminescence (CL) imaging strategy was developed through proximity hybridization to trigger the formation of a rolling circle-amplified G-quadruplex/hemin DNAzyme for the detection of the SARS-CoV-2 protein. The target protein was first recognized by a pair of DNA-antibody conjugates, Ab-1 and Ab-2, to form a proximity-ligated complex, Ab-1/SARS-CoV-2/Ab-2, which contained a DNA sequence complemental to block DNA and thus induced a strand displacement reaction to release the primer from a block/primer complex. The released primer then triggered a rolling circle amplification to form abundant DNAzyme units in the presence of hemin, which produced a strong chemiluminescent signal for the detection of the target protein by catalyzing the oxidation of luminol by hydrogen peroxide. The proposed assay showed a detectable concentration range over 5 orders of magnitude with the detection limit down to 6.46 fg/mL. The excellent selectivity, simple procedure, acceptable accuracy, and intrinsic high throughput of the imaging technique for analysis of serum samples demonstrated the potential applicability of the proposed detection method in clinical screening and diagnosis.


Subject(s)
Biosensing Techniques , COVID-19 , DNA, Catalytic , G-Quadruplexes , DNA, Catalytic/metabolism , Hemin , Humans , Immunoassay , Limit of Detection , Luminescence , SARS-CoV-2
7.
PLoS One ; 16(6): e0252628, 2021.
Article in English | MEDLINE | ID: covidwho-1256044

ABSTRACT

Serological assessment of SARS-CoV-2 specific responses are an essential tool for determining the prevalence of past SARS-CoV-2 infections in the population especially when testing occurs after symptoms have developed and limited contact tracing is in place. The goal of our study was to test a new 10-plex electro-chemiluminescence-based assay to measure IgM and IgG responses to the spike proteins from multiple human coronaviruses including SARS-CoV-2, assess the epitope specificity of the SARS-CoV-2 antibody response against full-length spike protein, receptor-binding domain and N-terminal domain of the spike protein, and the nucleocapsid protein. We carried out the assay on samples collected from three sample groups: subjects diagnosed with COVID-19 from the U.S. Army hospital at Camp Humphreys in Pyeongtaek, South Korea; healthcare administrators from the same hospital but with no reported diagnosis of COVID-19; and pre-pandemic samples. We found that the new CoV-specific multiplex assay was highly sensitive allowing plasma samples to be diluted 1:30,000 with a robust signal. The reactivity of IgG responses to SARS-CoV-2 nucleocapsid protein and IgM responses to SARS-CoV-2 spike protein could distinguish COVID-19 samples from non-COVID-19 and pre-pandemic samples. The data from the three sample groups also revealed a unique pattern of cross-reactivity between SARS-CoV-2 and SARS-CoV-1, MERS-CoV, and seasonal coronaviruses HKU1 and OC43. Our findings show that the CoV-2 IgM response is highly specific while the CoV-2 IgG response is more cross-reactive across a range of human CoVs and also showed that IgM and IgG responses show distinct patterns of epitope specificity. In summary, this multiplex assay was able to distinguish samples by COVID-19 status and characterize distinct trends in terms of cross-reactivity and fine-specificity in antibody responses, underscoring its potential value in diagnostic or serosurveillance efforts.


Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , SARS-CoV-2/immunology , Adult , Antibodies, Viral/analysis , Antibody Formation , Cross Reactions , Female , Humans , Immunoglobulin G/analysis , Immunoglobulin G/immunology , Immunoglobulin M/analysis , Immunoglobulin M/immunology , Luminescence , Male , Middle Aged , Middle East Respiratory Syndrome Coronavirus/immunology , Military Personnel , Nucleocapsid Proteins/immunology , SARS Virus/immunology , SARS-CoV-2/pathogenicity , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology , United States
8.
Front Public Health ; 9: 649781, 2021.
Article in English | MEDLINE | ID: covidwho-1231426

ABSTRACT

The onset of the new SARS-CoV-2 coronavirus encouraged the development of new serologic tests that could be additional and complementary to real-time RT-PCR-based assays. In such a context, the study of performances of available tests is urgently needed, as their use has just been initiated for seroprevalence assessment. The aim of this study was to compare four chemiluminescence immunoassays and one immunochromatography test for SARS-Cov-2 antibodies for the evaluation of the degree of diffusion of SARS-CoV-2 infection in Salerno Province (Campania Region, Italy). A total of 3,185 specimens from citizens were tested for anti-SARS-CoV-2 antibodies as part of a screening program. Four automated immunoassays (Abbott and Liaison SARS-CoV-2 CLIA IgG and Roche and Siemens SARS-CoV-2 CLIA IgM/IgG/IgA assays) and one lateral flow immunoassay (LFIA Technogenetics IgG-IgM COVID-19) were used. Seroprevalence in the entire cohort was 2.41, 2.10, 1.82, and 1.85% according to the Liaison IgG, Abbott IgG, Siemens, and Roche total Ig tests, respectively. When we explored the agreement among the rapid tests and the serologic assays, we reported good agreement for Abbott, Siemens, and Roche (Cohen's Kappa coefficient 0.69, 0.67, and 0.67, respectively), whereas we found moderate agreement for Liaison (Cohen's kappa coefficient 0.58). Our study showed that Abbott and Liaison SARS-CoV-2 CLIA IgG, Roche and Siemens SARS-CoV-2 CLIA IgM/IgG/IgA assays, and LFIA Technogenetics IgG-IgM COVID-19 have good agreement in seroprevalence assessment. In addition, our findings indicate that the prevalence of IgG and total Ig antibodies against SARS-CoV-2 at the time of the study was as low as around 3%, likely explaining the amplitude of the current second wave.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Immunoassay , Immunoglobulin M , Italy , Luminescence , Sensitivity and Specificity , Seroepidemiologic Studies
9.
Drug Deliv Transl Res ; 11(4): 1451-1455, 2021 08.
Article in English | MEDLINE | ID: covidwho-1217493

ABSTRACT

The importance of detection and treatments of infectious diseases has been stressed to the world by the ongoing COVID-19 pandemic. As a substitution of an external light source, self-luminescent therapeutics featuring in situ light emission aims to address the lack of tissue penetration in conventional photodynamic therapy (PDT). Luminol-based self-luminescent systems are successfully incorporated in PDT and detection of pathogens in infectious diseases. In these systems, luminol/hydrogen peroxide is served as luminescence source which can be activated by horseradish peroxidase (HRP). As a supplement strategy to the HRP-based bioluminescence, electrochemiluminescence (ECL) provided an electric-driven therapeutic solution and demonstrated potential capabilities of wearable healthcare devices with properly constructed transparent flexible hydrogels. Besides the diagnosis of infection and detection of bacteria, fungi and virus in solution or powder samples have been achieved by ATP-derived self-luminescence as the light source. In this inspirational note, we provide an overview on latest progress in the PDT and microbial detection by self-luminescent systems with an emphasis on the bioluminescence and ECL.


Subject(s)
Biosensing Techniques/methods , COVID-19/prevention & control , COVID-19/transmission , Luminescence , Photochemotherapy/methods , Animals , Biosensing Techniques/trends , COVID-19/metabolism , Communicable Diseases/metabolism , Communicable Diseases/transmission , Disease Transmission, Infectious/prevention & control , Humans , Photochemotherapy/trends
10.
J Med Virol ; 93(3): 1805-1809, 2021 03.
Article in English | MEDLINE | ID: covidwho-1196506

ABSTRACT

Plasma specimens from coronavirus disease 2019 patients were double-tested for anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies by two different batches of MAGLUMI 2019-nCov immunoglobulin M/immunoglobulin G (IgM/IgG) assays to evaluate IgM/IgG levels, qualitative interpretation, antibody kinetics, and linearity of diluted specimen. Here we show that (i) high-level IgM specimens need to be diluted with negative human plasma but not kit diluents and (ii) measured anti-SARS-CoV-2 IgM/IgG concentrations are substantially higher with later marketed immunoassay batch leading to (iii) the change of qualitative interpretation (positive vs. negative) in 12.3% of specimens measured for IgM, (iv) the informative time-course pattern of antibody production only when data from different immunoassay batches are not combined.


Subject(s)
COVID-19/blood , COVID-19/immunology , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin M/blood , Immunoglobulin M/immunology , SARS-CoV-2/immunology , Antibodies, Viral/immunology , COVID-19 Testing/methods , Humans , Immunoassay/methods , Luminescence , Luminescent Measurements/methods , Sensitivity and Specificity
11.
Nat Biotechnol ; 39(8): 928-935, 2021 08.
Article in English | MEDLINE | ID: covidwho-1152862

ABSTRACT

Current serology tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies mainly take the form of enzyme-linked immunosorbent assays, chemiluminescent microparticle immunoassays or lateral flow assays, which are either laborious, expensive or lacking sufficient sensitivity and scalability. Here we present the development and validation of a rapid, low-cost, solution-based assay to detect antibodies in serum, plasma, whole blood and to a lesser extent saliva, using rationally designed split luciferase antibody biosensors. This new assay, which generates quantitative results in 30 min, substantially reduces the complexity and improves the scalability of coronavirus disease 2019 (COVID-19) antibody tests. This assay is well-suited for point-of-care, broad population testing, and applications in low-resource settings, for monitoring host humoral responses to vaccination or viral infection.


Subject(s)
Antibodies, Viral/blood , Biosensing Techniques/methods , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Point-of-Care Systems , SARS-CoV-2/immunology , COVID-19/virology , Humans , Luminescence
13.
J Clin Lab Anal ; 35(1): e23649, 2021 Jan.
Article in English | MEDLINE | ID: covidwho-1064371

ABSTRACT

OBJECTIVE: To explore the clinical value of serum IgM and IgG to SARS-CoV-2 in COVID-19. METHODS: 105 COVID-19 patients were enrolled as the disease group. 197 non-COVID-19 patients served as the control group. Magnetic chemiluminescent immunoassay (MCLIA) was used to detect the IgM and IgG. RESULTS: The peak of positive rates of SARS-CoV-2 IgM was about 1 week earlier than that of IgG. It reached to peak within 15-21 days and then began a slowly decline. The positive rates of IgG were increased with the disease course and reached the peak between 22 and 39 days. The differences in sensitivity of the three detection modes (IgM, IgG, and IgM + IgG) were statistically significant. The largest group of test cases (illness onset 15-21 days) showed that the positive rate of IgG was higher than IgM. Also, the sensitivity of IgM combined with IgG was higher than IgM or IgG. IgM and IgG were monitored dynamically for 16 patients with COVID-19, the results showed that serological transformation of IgM was carried out simultaneously with IgG in seven patients, which was earlier than IgG in four patients and later than IgG in five patients. CONCLUSION: The detection of SARS-CoV-2 IgM and IgG is very important to determine the course of COVID-19. Nucleic acid detection combined with serum antibody of SARS-CoV-2 may be the best laboratory indicator for the diagnosis of SARS-CoV-2 infection and the phrase and predication for prognosis of COVID-19.


Subject(s)
COVID-19 Testing/methods , COVID-19/diagnosis , Immunoassay/methods , Immunoglobulin G/blood , Immunoglobulin M/blood , Adult , Antibodies, Viral/blood , Biomarkers/blood , Female , Humans , Luminescence , Male , Middle Aged , Retrospective Studies , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Seroconversion
15.
Virol J ; 18(1): 16, 2021 01 12.
Article in English | MEDLINE | ID: covidwho-1059645

ABSTRACT

BACKGROUND: SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature. METHODS: To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA). RESULTS: The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA. CONCLUSIONS: In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/blood , COVID-19 Serological Testing/methods , COVID-19/blood , Neutralization Tests/methods , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vesicular stomatitis Indiana virus/genetics , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/immunology , Cell Line , Convalescence , Humans , Inhibitory Concentration 50 , Luminescence , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
17.
Nature ; 591(7850): 482-487, 2021 03.
Article in English | MEDLINE | ID: covidwho-1049967

ABSTRACT

Naturally occurring protein switches have been repurposed for the development of biosensors and reporters for cellular and clinical applications1. However, the number of such switches is limited, and reengineering them is challenging. Here we show that a general class of protein-based biosensors can be created by inverting the flow of information through de novo designed protein switches in which the binding of a peptide key triggers biological outputs of interest2. The designed sensors are modular molecular devices with a closed dark state and an open luminescent state; analyte binding drives the switch from the closed to the open state. Because the sensor is based on the thermodynamic coupling of analyte binding to sensor activation, only one target binding domain is required, which simplifies sensor design and allows direct readout in solution. We create biosensors that can sensitively detect the anti-apoptosis protein BCL-2, the IgG1 Fc domain, the HER2 receptor, and Botulinum neurotoxin B, as well as biosensors for cardiac troponin I and an anti-hepatitis B virus antibody with the high sensitivity required to detect these molecules clinically. Given the need for diagnostic tools to track the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)3, we used the approach to design sensors for the SARS-CoV-2 spike protein and antibodies against the membrane and nucleocapsid proteins. The former, which incorporates a de novo designed spike receptor binding domain (RBD) binder4, has a limit of detection of 15 pM and a luminescence signal 50-fold higher than the background level. The modularity and sensitivity of the platform should enable the rapid construction of sensors for a wide range of analytes, and highlights the power of de novo protein design to create multi-state protein systems with new and useful functions.


Subject(s)
Antibodies, Viral/analysis , Biosensing Techniques/methods , Hepatitis B virus/immunology , SARS-CoV-2/chemistry , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/analysis , Troponin I/analysis , Antibodies, Viral/immunology , Biosensing Techniques/standards , Botulinum Toxins/analysis , Coronavirus Nucleocapsid Proteins/immunology , Immunoglobulin G/analysis , Immunoglobulin G/immunology , Limit of Detection , Luminescence , Phosphoproteins/immunology , Proto-Oncogene Proteins c-bcl-2/analysis , Receptor, ErbB-2/analysis , Sensitivity and Specificity , Viral Matrix Proteins/immunology
18.
Biosens Bioelectron ; 178: 113015, 2021 Apr 15.
Article in English | MEDLINE | ID: covidwho-1039299

ABSTRACT

Dependable, specific and rapid diagnostic methods for severe acute respiratory syndrome ß-coronavirus (SARS-CoV-2) detection are needed to promote public health interventions for coronavirus disease 2019 (COVID-19). Herein, we have established an entropy-driven amplified electrochemiluminescence (ECL) strategy to detect the RNA-dependent RNA polymerase (RdRp) gene of SARS-CoV-2 known as RdRp-COVID which as the target for SARS-CoV-2 plays an essential role in the diagnosis of COVID-19. For the construction of the sensors, DNA tetrahedron (DT) is modified on the surface of the electrode to furnish robust and programmable scaffolds materials, upon which target DNA-participated entropy-driven amplified reaction is efficiently conducted to link the Ru (bpy)32+ modified S3 to the linear ssDNA at the vertex of the tetrahedron and eventually present an "ECL on" state. The rigid tetrahedral structure of the DT probe enhances the ECL intensity and avoids the cross-reactivity between single-stranded DNA, thus increasing the sensitivity of the assays. The enzyme-free entropy-driven reaction prevents the use of expensive enzyme reagents and facilitates the realization of large-scale screening of SARS-CoV-2 patients. Our DT-based ECL sensor has demonstrated significant specificity and high sensitivity for SARS-CoV-2 with a limit of detection (LOD) down to 2.67 fM. Additionally, our operational method has achieved the detection of RdRp-COVID in human serum samples, which supplies a reliable and feasible sensing platform for the clinical bioanalysis.


Subject(s)
Biosensing Techniques/instrumentation , COVID-19 Nucleic Acid Testing/instrumentation , COVID-19/diagnosis , COVID-19/virology , Coronavirus RNA-Dependent RNA Polymerase/genetics , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Biosensing Techniques/statistics & numerical data , COVID-19 Nucleic Acid Testing/statistics & numerical data , Coronavirus RNA-Dependent RNA Polymerase/blood , DNA/chemistry , Electrochemical Techniques , Entropy , Genes, Viral , Humans , Limit of Detection , Luminescence , Nucleic Acid Conformation , Pandemics , Sensitivity and Specificity
19.
Nano Lett ; 21(2): 1017-1024, 2021 01 27.
Article in English | MEDLINE | ID: covidwho-1028800

ABSTRACT

Bioaerosols, including infectious diseases such as COVID-19, are a continuous threat to global public safety. Despite their importance, the development of a practical, real-time means of monitoring bioaerosols has remained elusive. Here, we present a novel, simple, and highly efficient means of obtaining enriched bioaerosol samples. Aerosols are collected into a thin and stable liquid film by the unique interaction of a superhydrophilic surface and a continuous two-phase centrifugal flow. We demonstrate that this method can provide a concentration enhancement ratio of ∼2.4 × 106 with a collection efficiency of ∼99.9% and an aerosol-into-liquid transfer rate of ∼95.9% at 500 nm particle size (smaller than a single bacterium). This transfer is effective in both laboratory and external ambient environments. The system has a low limit of detection of <50 CFU/m3air using a straightforward bioluminescence-based technique and shows significant potential for air monitoring in occupational and public-health applications.


Subject(s)
Aerosols , Bacteria/isolation & purification , Environmental Monitoring/instrumentation , Environmental Monitoring/methods , Air Microbiology , Biomass , Limit of Detection , Luminescence , Nanoparticles , Particle Size , Public Health , Surface Properties , Temperature
20.
Virol J ; 18(1): 16, 2021 01 12.
Article in English | MEDLINE | ID: covidwho-1024369

ABSTRACT

BACKGROUND: SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature. METHODS: To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA). RESULTS: The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA. CONCLUSIONS: In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/blood , COVID-19 Serological Testing/methods , COVID-19/blood , Neutralization Tests/methods , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vesicular stomatitis Indiana virus/genetics , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/immunology , Cell Line , Convalescence , Humans , Inhibitory Concentration 50 , Luminescence , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
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