Development of an Afordable ELISA Targeting the SARS‑CoV‑2 Nucleocapsid and Its Application to Samples from the Ongoing COVID‑19 Epidemic in Ghana
Date
2023
Authors
Journal Title
Journal ISSN
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Publisher
Molecular Diagnosis & Therapy
Abstract
Introduction The true nature of the population spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in
populations is often not fully known as most cases, particularly in Africa, are asymptomatic. Finding the true magnitude of
SARS-CoV-2 spread is crucial to provide actionable data about the epidemiological progress of the disease for researchers
and policymakers. This study developed and optimized an antibody enzyme-linked immunosorbent assay (ELISA) using
recombinant nucleocapsid antigen expressed in-house using a simple bacterial expression system.
Methods Nucleocapsid protein from SARS-CoV-2 was expressed and purifed from Escherichia coli. Plasma samples used
for the assay development were obtained from Ghanaian SARS-CoV-2 seropositive individuals during the pandemic, while
seronegative controls were plasma samples collected from blood donors before the coronavirus disease 2019 (COVID-19)
pandemic. Another set of seronegative controls was collected during the COVID-19 pandemic. Antibody detection and levels
within the samples were validated using commercial kits and Luminex. Analyses were performed using GraphPad Prism,
and the sensitivity, specificity and background cut-of were calculated.
Results and Discussion This low-cost ELISA (£0.96/test) assay has a high prediction of 98.9%, and sensitivity and specificity
of 97% and 99%, respectively. The assay was subsequently used to screen plasma from SARS-CoV-2 RT-PCR-positive Gha naians. The assay showed no signifcant diference in nucleocapsid antibody levels between symptomatic and asymptomatic,
with an increase of the levels over time. This is in line with our previous publication.
Conclusion This study developed a low-cost and transferable assay that enables highly sensitive and specific detection of
human anti-SARS-CoV-2 IgG antibodies. This assay can be modified to include additional antigens and used for continuous
monitoring of sero-exposure to SARS-CoV-2 in West Africa
Description
Research Article
Keywords
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), disease, enzyme-linked immunosorbent assay (ELISA)