Dataset Information

A point-of-care lateral flow assay for neutralising antibodies against SARS-CoV-2.

ABSTRACT:

Background

As vaccines against SARS-CoV-2 are now being rolled out, a better understanding of immunity to the virus, whether from infection, or passive or active immunisation, and the durability of this protection is required. This will benefit from the ability to measure antibody-based protection to SARS-CoV-2, ideally with rapid turnaround and without the need for laboratory-based testing.

Methods

We have developed a lateral flow POC test that can measure levels of RBD-ACE2 neutralising antibody (NAb) from whole blood, with a result that can be determined by eye or quantitatively on a small instrument. We compared our lateral flow test with the gold-standard microneutralisation assay, using samples from convalescent and vaccinated donors, as well as immunised macaques.

Findings

We show a high correlation between our lateral flow test with conventional neutralisation and that this test is applicable with animal samples. We also show that this assay is readily adaptable to test for protection to newly emerging SARS-CoV-2 variants, including the beta variant which revealed a marked reduction in NAb activity. Lastly, using a cohort of vaccinated humans, we demonstrate that our whole-blood test correlates closely with microneutralisation assay data (specificity 100% and sensitivity 96% at a microneutralisation cutoff of 1:40) and that fingerprick whole blood samples are sufficient for this test.

Interpretation

Taken together, the COVID-19 NAb-test^TM device described here provides a rapid readout of NAb based protection to SARS-CoV-2 at the point of care.

Funding

Support was received from the Victorian Operational Infrastructure Support Program and the Australian Government Department of Health. This work was supported by grants from the Department of Health and Human Services of the Victorian State Government; the ARC (CE140100011, CE140100036), the NHMRC (1113293, 2002317 and 1116530), and Medical Research Future Fund Awards (2005544, 2002073, 2002132). Individual researchers were supported by an NHMRC Emerging Leadership Level 1 Investigator Grants (1194036), NHMRC APPRISE Research Fellowship (1116530), NHMRC Leadership Investigator Grant (1173871), NHMRC Principal Research Fellowship (1137285), NHMRC Investigator Grants (1177174 and 1174555) and NHMRC Senior Principal Research Fellowships (1117766 and 1136322). Grateful support was also received from the A2 Milk Company and the Jack Ma Foundation.

SUBMITTER: Fulford TS

PROVIDER: S-EPMC8641961 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Last year, the novel coronavirus disease (COVID-19) emerged in Wuhan, and it has rapidly spread to many other countries and regions. COVID-19 exhibits a strong human-to-human transmission infectivity and could cause acute respiratory diseases. Asymptomatic carriers are able to infect other healthy persons, and this poses a challenge for public health; the World Health Organization (WHO) has already announced COVID-19 as a global pandemic. Nucleic acid testing, considered as the current primary method for diagnosing COVID-19, might lead to false negatives and is difficult to be applied for every suspected patient because of the existence of asymptomatic carriers. Meanwhile, detecting specific antibodies in blood, such as the IgM antibody, against the SARS-CoV-2 virus is another choice for COVID-19 diagnosis, as it is widely accepted that IgM is an important indicator in the acute infection period. In this study, a colloidal gold nanoparticle-based lateral-flow (AuNP-LF) assay was developed to achieve rapid diagnosis and on-site detection of the IgM antibody against the SARS-CoV-2 virus through the indirect immunochromatography method. For preparing AuNP-LF strips, the SARS-CoV-2 nucleoprotein (SARS-CoV-2 NP) was coated on an analytical membrane for sample capture, and antihuman IgM was conjugated with AuNPs to form the detecting reporter. Optimization of AuNP-LF assay was carried out by altering the pH value and the amount of antihuman IgM. The performance of AuNP-LF assay was evaluated by testing serum samples of COVID-19 patients and normal humans. The results were compared with the real-time polymerase chain reaction. The sensitivity and specificity of AuNP-LF assay were determined to be 100 and 93.3%, respectively, and an almost perfect agreement was exhibited by Kappa statistics (κ coefficient = 0.872). AuNP-LF assay showed outstanding selectivity in the detection of IgM against the SARS-CoV-2 virus with no interference from other viruses such as severe fever with thrombocytopenia syndrome virus (SFTSV) and dengue virus (DFV). AuNP-LF assay was able to achieve results within 15 min and needed only 10-20 μL serum for each test. As a whole, in the light of its advantages such as excellent specificity and stability, easy operation, low cost, and being less time-consuming, AuNP-LF assay is a feasible method for the diagnosis of COVID-19 in primary hospitals and laboratories, especially in emergency situations in which numerous samples need to be tested on time.