Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 11 de 11
Filter
1.
Clin Microbiol Infect ; 27(10): 1520.e7-1520.e10, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1297038

ABSTRACT

OBJECTIVES: Dexamethasone has become the standard of care for severe coronavirus disease 2019 (COVID-19), but its virological impact is poorly understood. The objectives of this work were to characterize the kinetics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) concentration in the upper respiratory tract (URT) and the antibody response in patients with (D+) and without (D-) dexamethasone treatment. METHODS: Data and biosamples from hospitalized patients with severe COVID-19, enrolled between 4th March and 11th December 2020 in a prospective observational study, were analysed. SARS-CoV-2 virus concentration in serial URT samples was measured using RT-PCR. SARS-CoV-2-specific immunoglobulins A and G (IgA and IgG) were measured in serum samples using S1-ELISA. RESULTS: We compared 101 immunocompetent patients who received dexamethasone (according to the inclusion criteria and dosage determined in the RECOVERY trial) to 93 immunocompetent patients with comparable disease severity from the first months of the pandemic, who had not been treated with dexamethasone or other glucocorticoids. We found no inter-group differences in virus concentration kinetics, duration of presence of viral loads >106 viral copies/mL (D+ median 17 days (IQR 13-24), D- 19 days (IQR 13-29)), or time from symptom onset until seroconversion (IgA: D+ median 11.5 days (IQR 11-12), D- 14 days (IQR 11.5-15.75); IgG: D+ 13 days (IQR 12-14.5), D- 12 days (IQR 11-15)). CONCLUSION: Dexamethasone does not appear to lead to a change in virus clearance or a delay in antibody response in immunocompetent patients hospitalized with severe COVID-19.


Subject(s)
Antibodies, Viral/blood , COVID-19/drug therapy , Dexamethasone/therapeutic use , SARS-CoV-2/isolation & purification , Anti-Inflammatory Agents/therapeutic use , COVID-19/blood , COVID-19/immunology , COVID-19/virology , Hospitalization , Humans , Immunoglobulin A/blood , Immunoglobulin G/blood , Kinetics , Prospective Studies , RNA, Viral/analysis , Respiratory System/virology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Seroconversion , Viral Load
2.
STAR Protoc ; 2(2): 100573, 2021 06 18.
Article in English | MEDLINE | ID: covidwho-1225430

ABSTRACT

This protocol describes an indirect enzyme-linked immunosorbent assay for qualitative detection of IgG antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Syrian hamster serum samples. We describe the preparation of inactivated virus antigens and the negative control antigen and the use of antigen-coated microtiter plates to detect SARS-CoV-2-specific antibodies from SARS-CoV-2-infected hamsters, including the criteria for differentiating positive versus negative reaction. The limited batch-to-batch variability of this assay has been verified with two batches of independently prepared antigens. For complete details on the use and execution of this protocol, please refer to Mohandas et al. (2021).


Subject(s)
Antibodies, Viral/blood , COVID-19/diagnosis , Coronavirus Nucleocapsid Proteins/immunology , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin G/blood , Immunologic Tests/methods , SARS-CoV-2/immunology , Animals , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/immunology , COVID-19/virology , Immunoglobulin G/immunology , Mesocricetus
3.
Trop Med Int Health ; 26(6): 621-631, 2021 06.
Article in English | MEDLINE | ID: covidwho-1119265

ABSTRACT

OBJECTIVES: Specific serological tests are mandatory for reliable SARS-CoV-2 diagnostics and seroprevalence studies. Here, we assess the specificities of four commercially available SARS-CoV-2 IgG ELISAs in serum/plasma panels originating from Africa, South America, and Europe. METHODS: 882 serum/plasma samples collected from symptom-free donors before the COVID-19 pandemic in three African countries (Ghana, Madagascar, Nigeria), Colombia, and Germany were analysed with three nucleocapsid-based ELISAs (Euroimmun Anti-SARS-CoV-2-NCP IgG, EDI™ Novel Coronavirus COVID-19 IgG, Mikrogen recomWell SARS-CoV-2 IgG), one spike/S1-based ELISA (Euroimmun Anti-SARS-CoV-2 IgG), and in-house common cold CoV ELISAs. RESULTS: High specificity was confirmed for all SARS-CoV-2 IgG ELISAs for Madagascan (93.4-99.4%), Colombian (97.8-100.0%), and German (95.9-100.0%) samples. In contrast, specificity was much lower for the Ghanaian and Nigerian serum panels (Ghana: NCP-based assays 77.7-89.7%, spike/S1-based assay 94.3%; Nigeria: NCP-based assays 39.3-82.7%, spike/S1-based assay 90.7%). 15 of 600 African sera were concordantly classified as positive in both the NCP-based and the spike/S1-based Euroimmun ELISA, but did not inhibit spike/ACE2 binding in a surrogate virus neutralisation test. IgG antibodies elicited by previous infections with common cold CoVs were found in all sample panels, including those from Madagascar, Colombia, and Germany and thus do not inevitably hamper assay specificity. Nevertheless, high levels of IgG antibodies interacting with OC43 NCP were found in all 15 SARS-CoV-2 NCP/spike/S1 ELISA positive sera. CONCLUSIONS: Depending on the chosen antigen and assay protocol, SARS-CoV-2 IgG ELISA specificity may be significantly reduced in certain populations probably due to interference of immune responses to endemic pathogens like other viruses or parasites.


Subject(s)
Antibodies, Viral/blood , COVID-19/diagnosis , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin G/blood , Adolescent , Adult , COVID-19/virology , Child , Child, Preschool , Colombia , Coronavirus Nucleocapsid Proteins/immunology , Female , Germany , Ghana , Humans , Madagascar , Male , Middle Aged , Nigeria , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology , Young Adult
4.
J Virol Methods ; 291: 114111, 2021 05.
Article in English | MEDLINE | ID: covidwho-1101403

ABSTRACT

Rapid, sensitive, and precise multiplexed assays for serological analysis during candidate COVID-19 vaccine development would streamline clinical trials. The VaxArray Coronavirus (CoV) SeroAssay quantifies IgG antibody binding to 9 pandemic, potentially pandemic, and endemic human CoV spike antigens in 2 h with automated results analysis. IgG antibodies in serum bind to the CoV spike protein capture antigens printed in a microarray format and are labeled with a fluorescent anti-species IgG secondary label. The assay demonstrated excellent lower limits of quantification ranging from 0.3 to 2.0 ng/mL and linear dynamic ranges of 76 to 911-fold. Average precision of 11 % CV and accuracy (% recovery) of 92.5 % over all capture antigens were achieved over 216 replicates representing 3 days and 3 microarray lots. Clinical performance on 263 human serum samples (132 SARS-CoV-2 negatives and 131 positives based on donor-matched RT-PCR and/or date of collection) produced 98.5 % PPA and 100 % NPA.


Subject(s)
Antibodies, Viral/blood , Coronavirus Infections/diagnosis , Coronavirus/isolation & purification , Microarray Analysis/methods , Serologic Tests/methods , Antigens, Viral/immunology , COVID-19/diagnosis , COVID-19/immunology , COVID-19 Nucleic Acid Testing , COVID-19 Testing/methods , Coronavirus/immunology , Coronavirus Infections/immunology , Humans , Immunoassay/methods , Immunoglobulin G/blood , Reproducibility of Results , SARS-CoV-2/isolation & purification , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology
5.
J Transl Med ; 19(1): 30, 2021 01 07.
Article in English | MEDLINE | ID: covidwho-1059718

ABSTRACT

BACKGROUND: COVID-19 has caused a global pandemic and the death toll is increasing. However, there is no definitive information regarding the type of clinical specimens that is the best for SARS-CoV-2 detection, the antibody levels in patients with different duration of disease, and the relationship between antibody level and viral load. METHODS: Nasopharyngeal swabs, anal swabs, saliva, blood, and urine specimens were collected from patients with a course of disease ranging from 7 to 69 days. Viral load in different specimen types was measured using droplet digital PCR (ddPCR). Meanwhile, anti-nucleocapsid protein (anti-N) IgM and IgG antibodies and anti-spike protein receptor-binding domain (anti-S-RBD) IgG antibody in all serum samples were tested using ELISA. RESULTS: The positive detection rate in nasopharyngeal swab was the highest (54.05%), followed by anal swab (24.32%), and the positive detection rate in saliva, blood, and urine was 16.22%, 10.81%, and 5.41%, respectively. However, some patients with negative nasopharyngeal swabs had other specimens tested positive. There was no significant correlation between antibody level and days after symptoms onset or viral load. CONCLUSIONS: Other specimens could be positive in patients with negative nasopharyngeal swabs, suggesting that for patients in the recovery period, specimens other than nasopharyngeal swabs should also be tested to avoid false negative results, and anal swabs are recommended. The antibody level had no correlation with days after symptoms onset or the viral load of nasopharyngeal swabs, suggesting that the antibody level may also be affected by other factors.


Subject(s)
Antibodies, Viral/blood , COVID-19/immunology , COVID-19/virology , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Viral Load , Adult , Aged , Aged, 80 and over , Anal Canal/virology , Blood/virology , COVID-19/epidemiology , COVID-19 Serological Testing , COVID-19 Testing , China/epidemiology , False Negative Reactions , Female , Humans , Male , Middle Aged , Nasopharynx/virology , Pandemics , Saliva/virology , Specimen Handling , Time Factors , Urine/virology
6.
J Transl Med ; 19(1): 30, 2021 01 07.
Article in English | MEDLINE | ID: covidwho-1015878

ABSTRACT

BACKGROUND: COVID-19 has caused a global pandemic and the death toll is increasing. However, there is no definitive information regarding the type of clinical specimens that is the best for SARS-CoV-2 detection, the antibody levels in patients with different duration of disease, and the relationship between antibody level and viral load. METHODS: Nasopharyngeal swabs, anal swabs, saliva, blood, and urine specimens were collected from patients with a course of disease ranging from 7 to 69 days. Viral load in different specimen types was measured using droplet digital PCR (ddPCR). Meanwhile, anti-nucleocapsid protein (anti-N) IgM and IgG antibodies and anti-spike protein receptor-binding domain (anti-S-RBD) IgG antibody in all serum samples were tested using ELISA. RESULTS: The positive detection rate in nasopharyngeal swab was the highest (54.05%), followed by anal swab (24.32%), and the positive detection rate in saliva, blood, and urine was 16.22%, 10.81%, and 5.41%, respectively. However, some patients with negative nasopharyngeal swabs had other specimens tested positive. There was no significant correlation between antibody level and days after symptoms onset or viral load. CONCLUSIONS: Other specimens could be positive in patients with negative nasopharyngeal swabs, suggesting that for patients in the recovery period, specimens other than nasopharyngeal swabs should also be tested to avoid false negative results, and anal swabs are recommended. The antibody level had no correlation with days after symptoms onset or the viral load of nasopharyngeal swabs, suggesting that the antibody level may also be affected by other factors.


Subject(s)
Antibodies, Viral/blood , COVID-19/immunology , COVID-19/virology , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Viral Load , Adult , Aged , Aged, 80 and over , Anal Canal/virology , Blood/virology , COVID-19/epidemiology , COVID-19 Serological Testing , COVID-19 Testing , China/epidemiology , False Negative Reactions , Female , Humans , Male , Middle Aged , Nasopharynx/virology , Pandemics , Saliva/virology , Specimen Handling , Time Factors , Urine/virology
7.
PLoS One ; 15(12): e0244348, 2020.
Article in English | MEDLINE | ID: covidwho-999840

ABSTRACT

BACKGROUND: The rapid spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) around the world has caused a global pandemic, infecting millions of individuals, with an unprecedented impact in health care systems worldwide. Healthcare workers are one of the risk groups that need to be well protected, due to their strategic role in patient management, presently and in prevention of healthcare needs for future outbreaks. Here, we present the results of the first SARS-CoV-2 seroprevalence study in the Northern Metropolitan Area of Barcelona, Spain. METHODS: IgG SARS-CoV-2 antibodies were analyzed in serum samples from 7563 healthcare workers of the Northern Metropolitan Area of Barcelona. Samples were collected after the first pandemic wave (from May 4th to May 22nd, 2020) and were analyzed by automated chemiluminescence assays. All samples were tested for IgG anti-S1/S2. Participant samples with negative or equivocal results but with analytical signals above the limit of detection and/or previously confirmed COVID-19 diagnosis were also tested for IgG anti-Nucleocapsid. RESULTS: A total of 779 of 7563 (10.3%) healthcare workers were positive for anti-SARS-CoV-2 IgG (specific for either S1/S2 or N antigens). No significant differences were observed between those working at primary care or at the reference hospital. Interestingly, among 341 participants with a confirmed COVID-19 diagnosis, 36 (10.55%) tested negative for SARS-CoV-2 IgG (both S1/S2 and recombinant N antigen). CONCLUSION: Seroprevalence of anti-SARS-CoV-2 IgG in the healthcare workers of the North Metropolitan Area of Barcelona was higher than in the general population in the same geographical area. Safety measures have to be stressed in order to protect these essential workers from future pandemic waves.


Subject(s)
Antibodies, Viral/immunology , COVID-19/immunology , Immunoglobulin G/immunology , SARS-CoV-2/immunology , Adolescent , Adult , Female , Health Personnel , Humans , Male , Middle Aged , Pandemics/prevention & control , Seroepidemiologic Studies , Spain , Young Adult
8.
Pediatr Investig ; 4(4): 236-241, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-996290

ABSTRACT

IMPORTANCE: In this study, we retrospectively investigated the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies within serum samples from children in Beijing, China. These findings provide preliminary guidance regarding population susceptibility to SARS-CoV-2, which will aid in establishing policy toward coronavirus disease 2019 (COVID-19) prevention and control. OBJECTIVE: To understand the seropositivity of anti-SARS-CoV-2 IgM/IgG antibodies among children in Beijing, China, evaluate the susceptibility of children in Beijing to SARS-CoV-2, and provide prima facie evidence to guide SARS-CoV-2 prevention and control. METHODS: IgM/IgG antibody kits (colloidal gold) were used to conduct preliminary screening of SARS-CoV-2 IgM/IgG antibodies in serum samples of children who presented to Beijing Children's Hospital, Capital Medical University, having fever or requiring hospitalization, from March 2020 to August 2020. Statistical analysis of anti-SARS-CoV-2 antibody seropositivity was performed according to the children's general demographic characteristics, timing of admission to hospital, presence of pneumonia, and viral nucleic acid test results. RESULTS: The study included 19 797 children with both IgM and IgG antibody results. Twenty-four children had anti-SARS-CoV-2 IgM-positive results (positive rate of 1.2‰), twelve children had anti-SARS-CoV-2 IgG-positive results (positive rate of 0.6‰). Viral nucleic acid test results were negative for the above-mentioned children with positive antibody findings; during the study, two children exhibited positive viral nucleic acid test results, but their anti-SARS-CoV-2 IgM/IgG antibody results were negative. Anti-SARS-CoV-2 IgM antibody seropositivity was higher in the <1-year-old group than in the ≥6-year-old group. The rates of anti-SARS-CoV-2 IgM seropositivity was highest in August from March to August; IgG results did not significantly differ over time. The rates of anti-SARS-CoV-2 IgM or IgG seropositivity among children with and without suspected pneumonia did not significantly differ between groups. INTERPRETATION: During the study period, the rates of anti-SARS-CoV-2 IgM/IgG antibody seropositivity were low among children who presented to Beijing Children's Hospital, Capital Medical University. The findings suggest that children in Beijing are generally susceptible to SARS-CoV-2 infection; COVID-19 prevention and control measures should be strengthened to prevent disease in children.

9.
Talanta ; 225: 122004, 2021 Apr 01.
Article in English | MEDLINE | ID: covidwho-974644

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the cause of Coronavirus Disease 2019 (COVID-19), poses extraordinary threats and complex challenges to global public health. Quantitative measurement of SARS-CoV-2 antibody titer plays an important role in understanding the patient-to-patient variability of immune response, assessing the efficacy of vaccines, and identifying donors for blood transfusion therapy. There is an urgent and ever-increasing demand for serological COVID-19 antibody tests that are highly sensitive, quantitative, rapid, simple, minimally invasive, and inexpensive. In this work, we developed a single-step, wash-free immunoassay for rapid and highly sensitive quantitative analysis of serological human IgG against SARS-CoV-2 which requires only a single droplet of serum. By simply incubating 4 µL human serum samples with antibody-functionalized gold nanoparticles, a photonic crystal optical biosensor coated with the recombinant spike protein serves as a sensing platform for the formation of sandwich immunocomplex through specific antigen-antibody interactions, upon which the detected IgG molecules can be counted with digital precision. We demonstrated a single-step 15-min assay capable of detecting as low as 100 pg mL-1 human COVID-19 IgG in serum samples. The calculated limit of detecting (LOD) and limit of quantification (LOQ) is 26.7 ± 7.7 and 32.0 ± 8.9 pg mL-1, respectively. This work represents the first utilization of the Activate Capture + Digital Counting (AC + DC)-based immunoassay for rapid and quantitative analysis of serological COVID-19 antibody, demonstrating a route toward point-of-care testing, using a portable detection instrument. On the basis of the sandwich immunoassay principle, the biosensing platform can be extended for the multiplexed detection of antigens, additional IgGs, cytokines, and other protein biomarkers.


Subject(s)
Antibodies, Viral/immunology , COVID-19/diagnosis , Immunoassay/methods , Immunoglobulin G/immunology , SARS-CoV-2/immunology , Antibodies, Viral/blood , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , COVID-19/virology , Gold/chemistry , Humans , Immunoglobulin G/blood , Metal Nanoparticles/chemistry , Microscopy/methods , SARS-CoV-2/physiology , Sensitivity and Specificity
10.
Biosens Bioelectron ; 177: 112672, 2021 Apr 01.
Article in English | MEDLINE | ID: covidwho-844839

ABSTRACT

Accurate, rapid, and low-cost molecular diagnostics is essential in managing outbreaks of infectious diseases, such as the pandemic of coronavirus disease 2019 (COVID-19). Accordingly, microfluidic paper-based analytical devices (µPADs) have emerged as promising diagnostic tools. Among the extensive efforts to improve the performance and usability of diagnostic tools, biosensing mechanisms based on electrochemical impedance spectroscopy (EIS) have shown great promise because of their label-free operation and high sensitivity. However, the method to improve EIS biosensing on µPADs is less explored. Here, we present an experimental approach to enhancing the performance of paper-based EIS biosensors featuring zinc oxide nanowires (ZnO NWs) directly grown on working electrodes (WEs). Through a comparison of different EIS settings and an examination of ZnO-NW effects on EIS measurements, we show that ZnO-NW-enhanced WEs function reliably with Faradaic processes utilizing iron-based electron mediators. We calibrate paper-based EIS biosensors with different morphologies of ZnO NWs and achieve a low limit of detection (0.4 pg ml-1) in detecting p24 antigen as a marker for human immunodeficiency virus (HIV). Through microscopic imaging and electrochemical characterization, we reveal that the morphological and the electrochemical surface areas of ZnO-NW-enhanced WEs indicate the sensitivities and sensing ranges of the EIS nanobiosensors. Finally, we report that the EIS nanobiosensors are capable of differentiating the concentrations (blank, 10 ng ml-1, 100 ng ml-1, and 1 µg ml-1) of IgG antibody (CR3022) to SARS-CoV-2 in human serum samples, demonstrating the efficacy of these devices for COVID-19 diagnosis. This work provides a methodology for the rational design of high-performance EIS µPADs and has the potential to facilitate diagnosis in pandemics.


Subject(s)
Biosensing Techniques/instrumentation , COVID-19 Serological Testing/instrumentation , COVID-19/diagnosis , Dielectric Spectroscopy/instrumentation , SARS-CoV-2/isolation & purification , Biosensing Techniques/methods , COVID-19/blood , COVID-19 Serological Testing/methods , Dielectric Spectroscopy/methods , Equipment Design , Humans , Lab-On-A-Chip Devices , Limit of Detection , Nanowires/chemistry , Paper , Zinc Oxide/chemistry
11.
ACS Omega ; 5(36): 23229-23236, 2020 Sep 15.
Article in English | MEDLINE | ID: covidwho-779934

ABSTRACT

The aim of this study is to establish a new method with high sensitivity, accuracy, and stability for the determination of human IgG and then expand it to analyze severe acute respiratory syndrome corona virus 2 (SARS-CoV-2)-specific IgM and IgG, which is of great significance for the screening and diagnosis of COVID-19. In this study, the magnetic Fe3O4 nanospheres coupled with mouse antihuman IgG (Ab1IgG) were used as an immune capture probe (Fe3O4@Ab1IgG) to capture and separate the target, and rabbit antihuman IgG (Ab2IgG) coupled with highly luminescent quantum dot nanobeads (QBs) as a fluorescence detection probe (QBs@Ab2IgG) was used to realize high sensitivity detection. After the formation of a sandwich immunocomplex, the fluorescence intensity of the precipitate after magnetic separation was measured at the excitation wavelength of 370 nm. Under optimal conditions, a wide linear range varying from 0.005 to 40 ng·mL-1 was obtained for the detection of human IgG with a lower limit of detection at 4 pg·mL-1 (S/N = 3). The recoveries of intra- and interassays were 90.0-101.9 and 96.0-106.6%, respectively, and the relative standard deviations were 6.3-10.2 and 2.6-10.5%, respectively. Furthermore, the proposed method was successfully demonstrated to detect human IgG in serum samples, and the detection results were not statistically different (P > 0.05) from commercial enzyme-linked immunosorbent assay kits. This method is sensitive, fast, and accurate, which could be expanded to detect the specific IgM and IgG antibodies against SARS-CoV-2.

SELECTION OF CITATIONS
SEARCH DETAIL