Evaluation of a flow cytometry-based surrogate assay (FlowSA) for the detection of SARS-CoV-2 in clinical samples

IF 1.6 Q4 INFECTIOUS DISEASES Journal of clinical virology plus Pub Date : 2025-02-01 DOI:10.1016/j.jcvp.2025.100204

Vinit Upasani , Marjolein Knoester , Daniele Pantano , Lili Gard , Jolanda M. Smit , Bernardina T.F. van der Gun , Adriana Tami , Izabela A. Rodenhuis-Zybert

{"title":"Evaluation of a flow cytometry-based surrogate assay (FlowSA) for the detection of SARS-CoV-2 in clinical samples","authors":"Vinit Upasani , Marjolein Knoester , Daniele Pantano , Lili Gard , Jolanda M. Smit , Bernardina T.F. van der Gun , Adriana Tami , Izabela A. Rodenhuis-Zybert","doi":"10.1016/j.jcvp.2025.100204","DOIUrl":null,"url":null,"abstract":"<div><h3>Introduction</h3><div>The current diagnostic methods for SARS-CoV-2 rely on quantitative RT-PCR. However, the presence of viral RNA in samples does not necessarily reflect the presence of an infectious virus. Therefore, the reliable detection of infectious SARS-CoV-2 in clinical samples is necessary to limit viral transmission.</div></div><div><h3>Methods</h3><div>We developed a flow cytometry-based surrogate assay (FlowSA), wherein the presence of infectious SARS-CoV-2 was detected using virus nucleocapsid-specific antibodies.</div></div><div><h3>Results</h3><div>We showed that FlowSA allows the detection of a wide range of viral titers of multiple SARS-CoV-2 variants. Furthermore, the assay was successfully used to detect infectious SARS-CoV-2 in nasopharyngeal swabs from SARS-CoV-2 positive individuals, including those with high Ct values. Notably, FlowSA identified the presence of infectious SARS-CoV-2 in biological specimens that scored negative for cytopathic effect (CPE) in cell culture and would otherwise be considered negative.</div></div><div><h3>Conclusion</h3><div>We propose that FlowSA can be adopted as an alternative to conventional CPE methods for viral diagnostics.</div></div>","PeriodicalId":73673,"journal":{"name":"Journal of clinical virology plus","volume":"5 1","pages":"Article 100204"},"PeriodicalIF":1.6000,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of clinical virology plus","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2667038025000031","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"INFECTIOUS DISEASES","Score":null,"Total":0}

引用次数: 0

Abstract

Introduction

The current diagnostic methods for SARS-CoV-2 rely on quantitative RT-PCR. However, the presence of viral RNA in samples does not necessarily reflect the presence of an infectious virus. Therefore, the reliable detection of infectious SARS-CoV-2 in clinical samples is necessary to limit viral transmission.

Methods

We developed a flow cytometry-based surrogate assay (FlowSA), wherein the presence of infectious SARS-CoV-2 was detected using virus nucleocapsid-specific antibodies.

Results

We showed that FlowSA allows the detection of a wide range of viral titers of multiple SARS-CoV-2 variants. Furthermore, the assay was successfully used to detect infectious SARS-CoV-2 in nasopharyngeal swabs from SARS-CoV-2 positive individuals, including those with high Ct values. Notably, FlowSA identified the presence of infectious SARS-CoV-2 in biological specimens that scored negative for cytopathic effect (CPE) in cell culture and would otherwise be considered negative.