Performance of the Diasorin SARS-CoV-2 antigen detection assay on the LIAISON XL

https://doi.org/10.1016/j.jcv.2021.104909Get rights and content

Highlights

  • We evaluated the performance of a direct two-step sandwich chemiluminescence immunoassay for the quantitative determination of SARS-CoV-2 nucleocapsid antigen compared to real-time RT-PCR.

  • We evaluated performance on clinical combined oro-nasopharyngeal samples obtained from symptomatic community-dwelling individuals. Furthermore, analytical performance with a 10-fold dilution series of SARS-CoV-2 containing culture supernatant was evaluated.

  • The assay performed adequately for clinical samples with a Ct-value below 30 (sensitivity 86% (CI95% 74.6%−93.3%)) and detected SARS-CoV-2 up to a dilution containing 5.2 × 102 TCID50/ml.

Abstract

Background

The current reference standard to diagnose a SARS-CoV-2 infection is real-time reverse transcriptase polymerase chain reaction (RT-PCR). This test poses substantial challenges for large-scale community testing, especially with respect to the long turnaround times. SARS-CoV-2 antigen tests are an alternative, but typically use a lateral flow assay format rendering them less suitable for analysis of large numbers of samples.

Methods

We conducted an evaluation of the Diasorin SARS-CoV-2 antigen detection assay (DAA) compared to real-time RT-PCR (Abbott). The study was performed on 248 (74 qRT-PCR positive, 174 qRT-PCR negative) clinical combined oro-nasopharyngeal samples of individuals with COVID-19-like symptoms obtained at a Municipal Health Service test centre. In addition, we evaluated the analytical performance of DAA with a 10-fold dilution series of SARS-CoV-2 containing culture supernatant and compared it with the lateral flow assay SARS-CoV-2 Roche/SD Biosensor Rapid Antigen test (RRA).

Results

The DAA had an overall specificity of 100% (95%CI 97.9%–100%) and sensitivity of 73% (95%CI 61.3%–82.7%) for the clinical samples. Sensitivity was 86% (CI95% 74.6%–93.3%) for samples with Ct-value below 30. Both the DAA and RRA detected SARS-CoV-2 up to a dilution containing 5.2 × 102 fifty-percent-tissue-culture-infective-dose (TCID50)/ml.

Discussion

The DAA performed adequately for clinical samples with a Ct-value below 30. Test performance may be further optimised by lowering the relative light unit (RLU) threshold for positivity assuming the in this study used pre-analytical protocol . The test has potential for use as a diagnostic assay for symptomatic community-dwelling individuals early after disease onset in the context of disease control.

Keywords

SARS-CoV-2
Evaluation
Antigen detection assay
Abbreviations. Real-time RT-PCR
Real-time reverse transcriptase polymerase chain reaction
LFA
Lateral flow assay
VTM
Virus transport medium
DAA
Diasorin SARS-CoV-2 Antigen detection assay
TCID50
Fifty-percent-tissue-culture-infective-dose
RRA
SARS-CoV-2 Roche/SD Biosensor Rapid Antigen test
GLY-medium
Gelatin-lactalbumin-yeast virus transport medium (Mediaproducts
Groningen
The Netherlands)
MHS
Municipal Health Services
LOD
Limit of detection

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1

Both authors contributed equally.

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