Neutralization Assays for SARS-CoV-2 Antibodies

Neutralization assays constitute the definitive means to quantify the functional capacity of antibodies to inhibit SARS-CoV-2 entry into host cells. By assessing how serum or monoclonal antibodies block virus–cell interactions, these tests provide critical insights into protective immunity following infection or vaccination. Live‐virus plaque reduction neutralisation tests (PRNTs) remain the traditional gold standard, yet they demand biosafety level 3 facilities and multi­day protocols. To overcome these constraints, surrogate systems have been developed, notably pseudovirus neutralisation assays that employ replication‐defective viral cores bearing the SARS-CoV-2 spike protein. These assays can be operated under biosafety level 2 conditions, offer versatility with fluorescent or luminescent readouts, and accommodate high‐throughput screening. Rapid point-of-care formats such as lateral flow immunoassays have also emerged, integrating competitive fluorescence or colourimetric detection to estimate neutralising titres in minutes. Collectively, these methods underpin seroepidemiological surveys, convalescent plasma therapy screening, monoclonal antibody development and vaccine evaluation, thereby playing a pivotal role in guiding public‐health responses to evolving viral variants.

Research from Nature Portfolio

Recent studies have refined fluorescence‐based neutralisation platforms to combine speed with gold‐standard accuracy. One approach uses a high‐throughput fluorescence reporter in a microplate format, yielding neutralisation titres comparable with plaque reduction tests while reducing assay time to under 24 hours and supporting large‐scale vaccine trials. Another development employs lentiviral pseudotypes with optimised reporter gene expression to measure neutralising responses over a broad dynamic range. This methodology has revealed the wide interindividual variability of antibody potency post-infection or vaccination, and has detected cross-reactive neutralising responses against related betacoronaviruses. These innovations demonstrate the feasibility of scalable, sensitive assays that maintain concordance with live‐virus benchmarks, thereby streamlining immunological monitoring across diverse laboratory settings.

Neutralization Assays for SARS-CoV-2 Antibodies publication trend

The graph below shows the total number of articles in neutralization assays for sars-cov-2 antibodies across all publications each year (not limited to Nature Index journals).

Technical terms

Neutralizing antibody: An antibody that binds a virus and prevents infection of target cells.

Pseudovirus neutralisation assay: A test using a replication-defective virus core bearing the SARS-CoV-2 spike to measure antibody-mediated inhibition under lower biosafety conditions.

Plaque reduction neutralisation test (PRNT): A live-virus assay that quantifies the dilution of serum required to reduce visible viral plaques by a defined percentage.

Lateral flow immunoassay: A rapid, paper‐based test that uses antibody–antigen binding and visual or fluorescent readouts for point-of-care detection.

Biosafety level (BSL): A classification of laboratory containment measures required to handle pathogens safely, ranging from BSL-1 (minimal risk) to BSL-4 (highest risk).

References

1. Fluorescence‐Quenching Lateral Flow Immunoassay for “Turn‐On” and Sensitive Detection of Anti‐SARS‐Cov‐2 Neutralizing Antibodies in Human Serum. Advanced Science (2023).
2. Development of a SARS‐CoV‐2 neutralization assay based on a pseudotyped virus using a HIV system. MedComm (2024).
3. Development of an automated, high-throughput SARS-CoV-2 neutralization assay based on a pseudotyped virus using a vesicular stomatitis virus (VSV) vector. Emerging Microbes & Infections (2023).