Affiliations 

  • 1 Department of Microbiology, Jahangirnagar University, Dhaka, Bangladesh
  • 2 Department of Research and Development, Gonoshasthaya-RNA Molecular Diagnostic & Research Center, Dhaka, Bangladesh
  • 3 Department of Diagnostic Laboratory, Enam Medical College and Hospital, Dhaka, Bangladesh
  • 4 Department of Pharmaceutical Sciences, School of Pharmacy, International University of Health and Welfare, Fukuoka, Japan
  • 5 Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
  • 6 Department of Life Science and Technology,School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
  • 7 Department of Biochemistry and Molecular Biology, Jahangirnagar University, Dhaka, Bangladesh
  • 8 Department of Physical Rehabilitation Sciences, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Kuantan, Malaysia
  • 9 Department of Community Medicine, Gonoshasthaya Samaj Vittik Medical College, Dhaka, Bangladesh
  • 10 The Unit of Pharmacology, Faculty of Medicine and Defence Health Universiti Pertahanan, Nasional Malaysia (National Defence University of Malaysia), Kuala Lumpur, Malaysia
  • 11 Department of Pharmacy, Brac University, Dhaka, Bangladesh
PMID: 34477019 DOI: 10.1080/14787210.2021.1976144

Abstract

BACKGROUND: Rapid increase in COVID-19 suspected cases has rendered disease diagnosis challenging, mainly depending upon RT-qPCR. Reliable, rapid, and cost-effective diagnostic assays that complement RT-qPCR should be introduced after thoroughly evaluating their performance upon various disease phases, viral load, and sample storage conditions.

OBJECTIVE: We investigated the correlation of cycle threshold (Ct) value, which implies the viral load and infection phase, and the storage condition of the clinical specimen with the diagnosis of SARS-CoV-2 through our newly developed in-house rapid enzyme-linked immunosorbent assay (ELISA) system.

METHOD: Naso-oropharyngeal samples of 339 COVID-19 suspected cases were collected and evaluated through RT-qPCR that were stored up to 30 days in different conditions (i.e. -80°C, -20°C and initially at 4°C followed by -80°C). The clinical specimens were evaluated with our in-house ELISA system after finalizing the assay method through checkerboard assay and minimizing the signal/noise ratio.

RESULT: The ELISA system showed the highest sensitivity (92.9%) for samples with Ct ≤30 and preserving at -80°C temperature. The sensitivity reduced proportionally with increasing Ct value and preserving temperature. However, the specificity ranged between 98.3% and 100%.

CONCLUSION: The results indicate the necessity of early infection phase diagnosis and lower temperature preservation of samples to perform rapid antigen ELISA tests.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.