Gold conjugated nanobodies in a signal-enhanced lateral flow test strip for rapid detection of SARS-CoV-2 S1 antigen in saliva samples

Theodor Bilharz Research Institute

Bibliographic Information

Authors: Maher S.; Kamel M.; Demerdash Z.; El Baz H.; Sayyouh O.; Saad A.; Ali N.; Salah F.; Atta S.

Journal: Scientific Reports

Publisher: Nature Research

Publication Date: 30 June 2023

Volume / Issue: Volume 13 / Issue 1

Article No.: 10643

ISSN: 20452322

DOI: 10.1038/s41598-023-37347-y

Scopus: View on Scopus

PubMed: 37391465

Document Type: Article

Access: All Open Access; Gold Open Access; Green Open Access

Authors and Affiliations

Maher S., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Kamel M., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Demerdash Z., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; El Baz H., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Sayyouh O., Infection Control and Clinical Microbiology, Theodor Bilharz Research Institute, Giza, Egypt; Saad A., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Ali N., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Salah F., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt; Atta S., Immunology Department, Theodor Bilharz Research Institute, Giza, Egypt

Abstract

Despite the transfer of COVID-19 from the pandemic to control, we are still in a state of uncertainty about long-term success. Therefore, there is a great need for rapid and sensitive diagnostics to sustain the control status. After several optimization trials, we developed lateral flow test (LFT) strips for rapid detection of SARS-CoV-2 spike 1 (S1) antigen in saliva samples. For signal enhancement of our developed strips, we applied dual gold conjugates. Gold-labeled anti-S1 nanobodies (Nbs) were employed as S1 detector conjugate, while gold-labeled angiotensin-converting enzyme 2 (ACE2) was used as S1 capturing conjugate. In a parallel strip design, we used an anti-S1 monoclonal antibody (mAb) as an antigen detector instead of anti-S1 Nbs. Saliva samples were collected from 320 symptomatic subjects (180 RT-PCR confirmed positive cases and 140 confirmed negative cases) and were tested with the developed strips. In early detection for positive samples with cycle threshold (Ct ≤ 30), Nbs-based LFT strips showed higher sensitivity (97.14%) and specificity (98.57%) than mAb-based strips which gave 90.04% sensitivity and 97.86% specificity. Moreover, the limit of detection (LoD) for virus particles was lower for Nbs-based LFT (0.4 × 104 copies/ml) than for the mAb-based test (1.6 × 104 copies/ml). Our results are in favor of the use of dual gold Nbs and ACE2 conjugates in LFT strips. These signal-enhanced strips offer a sensitive diagnostic tool for rapid screening of SARS-CoV-2 S1 antigen in the easily collected saliva samples. © 2023, The Author(s).

Keywords

Angiotensin-Converting Enzyme 2; Antibodies, Monoclonal; COVID-19; Humans; Saliva; SARS-CoV-2; Single-Domain Antibodies; angiotensin converting enzyme 2; monoclonal antibody; nanobody; sarcoma-associated antigen S1; coronavirus disease 2019; human; Severe acute respiratory syndrome coronavirus 2

Citation Information

Scopus Citations: 20

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