Electrochemical Capillary-Flow Immunoassay for Detecting Anti-SARS-CoV-2 Nucleocapsid Protein Antibodies at the Point of Care
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ABSTRACT:
SUBMITTER: Samper I
PROVIDER: S-EPMC8565458 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The COVID-19 pandemic focused attention on a pressing need for fast, accurate, and low-cost diagnostic tests. This work presents an electrochemical capillary driven immunoassay (eCaDI) developed to detect SARS-CoV-2 nucleocapsid (N) protein. The low-cost flow device is made of polyethylene terephthalate (PET) and adhesive films. Upon addition of a sample, reagents and washes are sequentially delivered to an integrated screen-printed carbon electrode for detection, thus automating a full sandwich immunoassay with a single end-user step. The modified electrodes are sensitive and selective for SARS-CoV-2 N protein and stable for over 7 weeks. The eCaDI was tested with influenza A and Sindbis virus and proved to be selective. The eCaDI was also successfully applied to detect nine different SARS-CoV-2 variants, including Omicron.
| S-EPMC9469961 | biostudies-literature
Project description:Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment, and mitigation of COVID-19. Assays for SARS-CoV2 using reverse transcription polymerase chain reaction (RT-PCR) offer good sensitivity and excellent specificity, but are expensive, slowed by transport to centralized testing laboratories, and often unavailable. Antigen-based assays are inexpensive and can be rapidly mass-produced and deployed at point-of-care, with lateral flow assays (LFAs) being the most common format. While various manufacturers have produced commercially available SARS-Cov2 antigen LFAs, access to validated tests remains difficult or cost prohibitive in low-and middle-income countries. Herein, we present a visually read open-access LFA (OA-LFA) using commercially-available antibodies and materials for the detection of SARS-CoV-2. The LFA yielded a Limit of Detection (LOD) of 4 TCID50/swab of gamma irradiated SARS-CoV-2 virus, meeting the acceptable analytical sensitivity outlined by in World Health Organization target product profile. The open-source architecture presented in this manuscript provides a template for manufacturers around the globe to rapidly design a SARS-CoV2 antigen test.
| S-EPMC8580225 | biostudies-literature
Project description:The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably rapid and inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance, they require highly optimized antibodies and assay conditions. We used an automated liquid handling system, customized to handle arrays of lateral flow (immuno)assays (LFAs) in a high-throughput screen, to identify anti-nucleocapsid antibodies that will perform optimally in an LFA. We tested 1021 anti-nucleocapsid antibody pairs as LFA capture and detection reagents with the goal of highlighting pairs that have the greatest affinity for the nucleocapsid protein of SARS-CoV-2 within the LFA format. In contrast to traditional antibody screening methods (e.g., ELISA, bio-layer interferometry), the method described here integrates real-time reaction kinetics with transport in, and immobilization directly onto, nitrocellulose. We have identified several candidate antibody pairs that are suitable for further development of an LFA for SARS-CoV-2.
| S-EPMC8482319 | biostudies-literature
Project description:Past severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is an important determinant of protection from reinfection and of postvaccine immune responses. Herein, we conducted a follow-up analysis of health care workers previously infected with coronavirus disease 2019 (COVID-19) with the aim of evaluating different immunoassays for their capability in detecting the waning anti-SARS-CoV-2 immune responses and accuracy in documenting past SARS-CoV-2 infections. We evaluated serum antinucleocapsid antibody levels in convalescent individuals following a 1.5-year interval from SARS-CoV-2 infection. Three different commercial immunoassays that qualitatively measure serum antibodies targeting the SARS-CoV-2 nucleocapsid protein, namely, the Abbott Architect SARS-CoV-2 IgG, the Euroimmun anti-SARS-CoV-2 NCP enzyme-linked immunosorbent assay (ELISA) IgG, and the Roche Elecsys anti-SARS-CoV-2, were tested for comparison of detectability. A total of 38 individuals consented to participating in this follow-up analysis. From assay to assay, seropositivity rate at 18 months from infection varied from lowest at 42% to highest at 92%. The Roche Elecsys immunoassay, dependent on the dual-antigen antibody detection method and tuned for the detection of high avidity antibodies, was most capable of accurately documenting past SARS-CoV-2 infections. Different immunoassays showed variable capability of determining previous infection status under waning antibody concentrations. Immunoassays with lower detection limits are to be selected, and adjusted thresholds are to be considered in order to maximize the tests' performance. IMPORTANCE Past SARS-CoV-2 infection is an important determinant of protection from reinfection and of postvaccine immune responses. Our results show that different immunoassays, by design, harbor variable capability of tracking SARS-CoV-2 infection under waning antibody concentrations. With each recovered patient standing at a unique time point along the decline curve of antibodies, precise estimation of COVID-19 cumulative incidence remains a challenge. Since future surveillance studies will be targeting more than ever heterogenous cohorts, selecting the appropriate immunoassay is crucial in order to assure reliable decisions about an individual's previous infection status.
| S-EPMC9430644 | biostudies-literature
Project description:The level of anti-SARS-CoV-2 neutralizing antibodies (NAb) is an indispensable reference for evaluating the acquired protective immunity against SARS-CoV-2. Here, we established an ultrabright nanoparticles-based lateral flow immunoassay (LFIA) for one-step rapid semi-quantitative detection of anti-SARS-CoV-2 NAb in vaccinee's serum. Once embedded in polystyrene (PS) nanoparticles, the aggregation-induced emission (AIE) luminogen, AIE490, exhibited ultrabright fluorescence due to the rigidity of PS and severe inhibition of intramolecular motions. The ultrabright AIE490-PS nanoparticle was used as a fluorescent marker of LFIA. Upon optimized conditions including incubation time, concentrations of coated proteins and conjugated nanoparticles, amounts of antigens modified on the surface of nanoparticles, dilution rate of serum samples, and so on, the ultrabright nanoparticles-based LFIA could accurately identify 70 negative samples and 63 positive samples from human serum (p < 0.0001). The intra- and inter-assay precisions of the established method are above 13% and 16%, respectively. The established LFIA has tremendous practical value of generalization as a rapid semi-quantitative detection method of anti-SARS-CoV-2 NAb. Meanwhile, the AIE490-PS nanoparticle is also promising to detect many other analytes by altering the protein on the surface.
| S-EPMC9360774 | biostudies-literature
Project description:The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) is still raging all over the world. Hence, the rapid and sensitive screening of the suspected population is in high demand. The nucleocapsid protein (NP) of SARS-CoV-2 has been selected as an ideal marker for viral antigen detection. This study describes a lateral flow immunoassay (LFIA) based on colloidal gold nanoparticles for rapid NP antigen detection, in which sensitivity was improved through copper deposition-induced signal amplification. The detection sensitivity of the developed LFIA for NP antigen detection (using certified reference materials) under the optimized parameters was 0.01 μg/mL and was promoted by three orders of magnitude to 10 pg/mL after copper deposition signal amplification. The LFIA coupled with the copper enhancement technique has many merits such as low cost, high efficiency, and high sensitivity. It provides an effective approach to the rapid screening, diagnosis, and monitoring of the suspected population in the COVID-19 outbreak.
| S-EPMC8773578 | biostudies-literature
Project description:The titer of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies (NAbs) in the human body is an essential reference for evaluating the acquired protective immunity and resistance to SARS-CoV-2 infection. In this study, a fluorescence-quenching lateral flow immunoassay (FQ-LFIA) is established for quantitative detection of anti-SARS-CoV-2 NAbs in the sera of individuals who are vaccinated or infected within 10 min. The ultrabright aggregation-induced emission properties encapsulated in nanoparticles, AIE490 NP, are applied in the established FQ-LFIA with gold nanoparticles to achieve a fluorescence "turn-on" competitive immunoassay. Under optimized conditions, the FQ-LFIA quantitatively detected 103 positive and 50 negative human serum samples with a limit of detection (LoD) of 1.29 IU mL-1 . A strong correlation is present with the conventional pseudovirus-based virus neutralization test (R2 = 0.9796, P < 0.0001). In contrast, the traditional LFIA with a "turn-off" mode can only achieve a LoD of 11.06 IU mL-1 . The FQ-LFIA showed excellent sensitivity to anti-SARS-CoV-2 NAbs. The intra- and inter-assay precisions of the established method are below 15%. The established FQ-LFIA has promising potential as a rapid and quantitative method for detecting anti-SARS-CoV-2 NAbs. FQ-LFIA can also be used to detect various biomarkers.
| S-EPMC10811470 | biostudies-literature
Project description:A better understanding of the anti-SARS-CoV-2 immune response is necessary to finely evaluate commercial serological assays but also to predict protection against reinfection and to help the development of vaccines. For this reason, we monitored the anti-SARS-CoV-2 antibody response in infected patients. In order to assess the time of seroconversion, we used 151 samples from 30 COVID-19 inpatients and monitored the detection kinetics of anti-S1, anti-S2, anti-RBD and anti-N antibodies with in-house ELISAs. We observed that specific antibodies were detectable in all inpatients 2 weeks post-symptom onset and that the detection of the SARS-CoV-2 Nucleocapsid and RBD was more sensitive than the detection of the S1 or S2 subunits. Using retroviral particles pseudotyped with the spike of the SARS-CoV-2, we also monitored the presence of neutralizing antibodies in these samples as well as 25 samples from asymptomatic individuals that were shown SARS-CoV-2 seropositive using commercial serological tests. Neutralizing antibodies reached a plateau 2 weeks post-symptom onset and then declined in the majority of inpatients but they were undetectable in 56% of asymptomatic patients. Our results indicate that the SARS-CoV-2 does not induce a prolonged neutralizing antibody response. They also suggest that induction of neutralizing antibodies is not the only strategy to adopt for the development of a vaccine. Finally, they imply that anti-SARS-CoV-2 neutralizing antibodies should be titrated to optimize convalescent plasma therapy.
| S-EPMC7604306 | biostudies-literature
Project description:ObjectivesSerological studies have been critical in tracking the evolution of the COVID-19 pandemic. Data on anti-SARS-CoV-2 antibodies persistence remain sparse, especially from infected individuals with few to no symptoms. The objective of the study was to quantify the sensitivity for detecting historic SARS-CoV-2 infections as a function of time since infection for three commercially available SARS-CoV-2 immunoassays and to explore the implications of decaying immunoassay sensitivity in estimating seroprevalence.MethodsWe followed a cohort of mostly mild/asymptomatic SARS-CoV-2-infected individuals (n = 354) at least 8 months after their presumed infection date and tested their serum for anti-SARS-CoV-2 antibodies with three commercially available assays: Roche-N, Roche-RBD and EuroImmun-S1. We developed a latent class statistical model to infer the specificity and time-varying sensitivity of each assay and show through simulations how inappropriately accounting for test performance can lead to biased serosurvey estimates.ResultsAntibodies were detected at follow-up in 74-100% of participants, depending on immunoassays. Both Roche assays maintain high sensitivity, with the EuroImmun assay missing 40% of infections after 9 months. Simulations reveal that without appropriate adjustment for time-varying assay sensitivity, seroprevalence surveys may underestimate infection rates.DiscussionAntibodies persist for at least 8 months after infection in a cohort of mildly infected individuals with detection depending on assay choice. Appropriate assay performance adjustment is important for the interpretation of serological studies in the case of diminishing sensitivity after infection.
| S-EPMC8261139 | biostudies-literature
Project description:ObjectivesWe validate the use of a lateral flow immunoassay (LFI) intended for rapid screening and qualitative detection of anti-SARS-CoV-2 IgM and IgG in serum, plasma, and whole blood, and compare results with ELISA. We also seek to establish the value of LFI testing on blood obtained from a capillary blood sample.MethodsSamples collected by venous blood draw and finger stick were obtained from patients with SARS-CoV-2 detected by RT-qPCR and control patients. Samples were tested with Biolidics 2019-nCoV IgG/IgM Detection Kit lateral flow immunoassay, and antibody calls were compared with ELISA.ResultsBiolidics LFI showed clinical sensitivity of 92% with venous blood at 7 days after PCR diagnosis of SARS-CoV-2. Test specificity was 92% for IgM and 100% for IgG. There was no significant difference in detecting IgM and IgG with Biolidics LFI and ELISA at D0 and D7 (p = 1.00), except for detection of IgM at D7 (p = 0.04). Capillary blood of SARS-CoV-2 patients showed 93% sensitivity for antibody detection.ConclusionsClinical performance of Biolidics 2019-nCoV IgG/IgM Detection Kit is comparable to ELISA and was consistent across sample types. This provides an opportunity for decentralized rapid testing and may allow point-of-care and longitudinal self-testing for the presence of anti-SARS-CoV-2 antibodies.
| S-EPMC7647890 | biostudies-literature