International Journal of Nanomedicine (Jul 2021)

AuNP Coupled Rapid Flow-Through Dot-Blot Immuno-Assay for Enhanced Detection of SARS-CoV-2 Specific Nucleocapsid and Receptor Binding Domain IgG

  • Sil BK,
  • Jamiruddin MR,
  • Haq MA,
  • Khondoker MU,
  • Jahan N,
  • Khandker SS,
  • Ali T,
  • Oishee MJ,
  • Kaitsuka T,
  • Mie M,
  • Tomizawa K,
  • Kobatake E,
  • Haque M,
  • Adnan N

Journal volume & issue
Vol. Volume 16
pp. 4739 – 4753

Abstract

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Bijon Kumar Sil,1 Mohd Raeed Jamiruddin,2 Md Ahsanul Haq,1 Mohib Ullah Khondoker,3 Nowshin Jahan,1 Shahad Saif Khandker,1 Tamanna Ali,1 Mumtarin Jannat Oishee,1 Taku Kaitsuka,4 Masayasu Mie,5 Kazuhito Tomizawa,6 Eiry Kobatake,5 Mainul Haque,7 Nihad Adnan8 1Gonoshasthaya-RNA Molecular Diagnostic and Research Center, Dhaka, 1205, Bangladesh; 2Department of Pharmacy, BRAC University, Dhaka, 1212, Bangladesh; 3Gonoshasthaya Samaj Vittik Medical College, Savar, Dhaka, 1344, Bangladesh; 4School of Pharmacy, International University of Health and Welfare, Okawa, Fukuoka, 831-8501, Japan; 5School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8502, Japan; 6Department of Molecular Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan; 7The Unit of Pharmacology, Faculty of Medicine and Defence Health Universiti Pertahanan, Nasional Malaysia (National Defence University of Malaysia), Kuala Lumpur, 57000, Malaysia; 8Department of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshCorrespondence: Nihad AdnanDepartment of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshTel +8801705709910Email [email protected] HaqueThe Unit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan, Nasional Malaysia (National Defence University of Malaysia), Kem Perdana Sungai Besi, Kuala Lumpur, 57000, MalaysiaTel +60109265543Email [email protected]: Serological tests detecting severe acute respiratory syndrome coronavirus− 2 (SARS-CoV-2) are widely used in seroprevalence studies and evaluating the efficacy of the vaccination program. Some of the widely used serological testing techniques are enzyme-linked immune-sorbent assay (ELISA), chemiluminescence immunoassay (CLIA), and lateral flow immunoassay (LFIA). However, these tests are plagued with low sensitivity or specificity, time-consuming, labor-intensive, and expensive. We developed a serological test implementing flow-through dot-blot assay (FT-DBA) for SARS-CoV-2 specific IgG detection, which provides enhanced sensitivity and specificity while being quick to perform and easy to use.Methods: SARS-CoV-2 antigens were immobilized on nitrocellulose membrane to capture human IgG, which was then detected with anti-human IgG conjugated gold nanoparticle (hIgG-AuNP). A total of 181 samples were analyzed in-house. Within which 35 were further evaluated in US FDA-approved CLIA Elecsys SARS-CoV-2 assay. The positive panel consisted of RT-qPCR positive samples from patients with both 14 days from the onset of clinical symptoms. The negative panel contained samples collected from the pre-pandemic era dengue patients and healthy donors during the pandemic. Moreover, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FT-DBA were evaluated against RT-qPCR positive sera. However, the overall efficacies were assessed with sera that seroconverted against either nucleocapsid (NCP) or receptor-binding domain (RBD).Results: In-house ELISA selected a total of 81 true seropositive and 100 seronegative samples. The sensitivity of samples with 14 days. The overall detection sensitivity and specificity were 98.8% and 98%, respectively, whereas the overall PPV and NPV were 99.6% and 99%. Moreover, comparative analysis between in-house ELISA assays and FT-DBA revealed clinical agreement of Cohen’s Kappa value of 0.944. The FT-DBA showed sensitivity and specificity of 100% when compared with commercial CLIA kits.Conclusion: The assay can confirm past SARS-CoV-2 infection with high accuracy within 2 minutes compared to commercial CLIA or in-house ELISA. It can help track SARS-CoV-2 disease progression, population screening, and vaccination response. The ease of use of the assay without requiring any instruments while being semi-quantitative provides the avenue of its implementation in remote areas around the globe, where conventional serodiagnosis is not feasible.Keywords: COVID-19, SARS-CoV-2, dot-blot immunoassay, AuNP, gold nanoparticle, serosurveillance, nucleocapsid, receptor binding domain

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