SENSITIVE DETECTION OF SARS-COV-2 USING AN ENZYME-LINKED OLIGONUCLEOTIDE ASSAY
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Date
2022-06
Authors
Shola David, Michael
Journal Title
Journal ISSN
Volume Title
Publisher
Nazarbayev University School of Sciences and Humanities
Abstract
The rapid spread of COVID’19 has necessitated the need for the development of rapid diagnostic
techniques as a strategy to contain further transmission of the virus. Aptamer-based detection assay
like enzyme-linked oligonucleotide assay (ELONA) is promising as it is cheaper to run with high
sensitivity and specificity. Aptamers offer a potential advantage over antibodies in the
characteristics of broad modification, small size, in vitro selection, and stability under stringent
conditions, which assist the creation of scalable and reliable detection. In this study, we sought to
develop a simple and sensitive ELONA detection tool for SARS-CoV-2 using specific aptamers
against SARS-CoV-2 RBD S protein. Screening of CoV2-RBD-1C and CoV2-RBD-4C aptamers
and optimization of the assay conditions led to the development of a direct ELONA able to detect
SARS-CoV-2 RBD S protein in buffer solution and spiked in 0.1% human nasal fluid with a
detection limit of 2.16 ng/mL and 1.02 ng/mL, respectively. To further test the practicality of the
developed assay, we successfully detected inactivated Alpha, Wuhan, and Delta variants of SARS CoV-2 with a detection limit of 3.73, 5.72, and 6.02 TCID50/mL respectively. Furthermore, we
applied the two aptamers as capture and reporter elements to develop a more sensitive sandwich
assay to detect the three variants of SARS-CoV-2 used in this study, and as expected a lower
detection limit was obtained as follows: 2.31 TCID50/mL for Alpha variant, 1.15 TCID50/mL for
Wuhan variant, and 2.96 TCID50/mL for Delta variant, which validated the high sensitivity of the
sandwich assay. The sandwich ELONA was also capable of detecting both Alpha as well as Wuhan
variants spiked in 0.1% human nasal fluid in a viral titer of 104 TCID50/mL. Finally, an SEM study
was conducted to visualize the presence of viral particles in the Delta variant sample obtained. The
results of this study have demonstrated the possibility and usefulness of our aptamer-based assay
for the clinical diagnosis of SARS-COV-2
Description
Keywords
Type of access: Embargo, SARS-CoV-2, RBD, spike protein, aptamers, ELONA, detection
Citation
Michael Shola David. 2022. Sensitive detection of SARS-COV-2 using an enzyme-linked oligonucleotide assay. School of Sciences and Humanities