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Updated: Oct 29, 2025
An Improved and High Throughput Respiratory Syncytial Virus RSV Micro-neutralization Assay
Published on: January 26, 2019
RSV neutralization assays - Use in immune response assessment
Rama Raghunandan1, Deborah Higgins1, Nancy Hosken1
1PATH, Seattle, WA, USA.
Insights
Standardizing respiratory syncytial virus (RSV) neutralization assays is crucial for evaluating vaccine efficacy. The WHO International Standard for Antiserum to RSV harmonizes results across labs and methods, aiding vaccine development.
Area of Science:
- Virology
- Immunology
- Vaccinology
Background:
- Respiratory syncytial virus (RSV) is a major cause of respiratory illness in children globally, with no licensed vaccine available.
- Current RSV vaccine candidates aim to elicit virus-neutralizing antibodies (nAbs), a validated correlate of protection.
- Existing nAb assays lack standardization, hindering comparative analysis of vaccine immunogenicity.
Purpose of the Study:
- To review current RSV neutralization assay formats.
- To highlight the importance of assay standardization for vaccine development.
- To introduce the WHO 1st International Standard for Antiserum to RSV (RSV IS) as a tool for harmonization.
Main Methods:
- Review of various RSV virus neutralization assay formats.
- Discussion of the application of the WHO RSV IS for harmonizing nAb titer measurements.
- Outline of good practices for assay components and data analysis.
Main Results:
- A wide variety of RSV neutralization assay formats are currently in use.
- The WHO RSV IS effectively harmonizes nAb titer results across different laboratories and assay formats for RSV/A and RSV/B.
- Standardization is essential for consistent and comparable assessment of nAb responses.
Conclusions:
- Standardizing RSV neutralization assays is critical for accurate assessment of vaccine candidates.
- The WHO RSV IS provides a common reference standard to harmonize results, facilitating vaccine development.
- Adoption of good laboratory practices and the RSV IS will improve the quality and consistency of nAb titer measurements.
Abstract:
Respiratory syncytial virus (RSV) is a leading cause of respiratory illness among children and infants worldwide, yet no licensed vaccine exists to reduce the risk of disease. At least 16 RSV vaccine candidates are currently in clinical development and many are designed to induce robust virus neutralizing immune responses. RSV neutralizing antibody (nAb)-mediated interventions such as intravenous immunoglobulin (IVIG) and palivizumab provide passive protection against serious lower respiratory tract disease due to RSV, validating nAbs as a correlate of protection. To identify correlates of protection for vaccine candidates that have demonstrated their protective efficacy, an investigator can use assays designed to measure nAb responses. However, there is no standard method of measurement; individual laboratories have developed their own methods to measure the ability of nAbs to reduce the infectivity of a defined virus dose in a variety of cell lines, leading to establishment of the broad variety of RSV neutralization assay formats currently in use. Standardizing the RSV neutralization assay is an essential step toward better assessment of nAb responses to vaccine candidates. Use of a common reference standard by all makes comparing the immunogenicity of different vaccine candidates feasible. In the context of vaccine development, the WHO 1st International Standard for Antiserum to RSV (RSV IS) has been shown to be suitable for harmonizing results across laboratories and assay formats used to measure nAb titers to RSV/A and RSV/B in human sera. This review describes the broad variety of RSV virus neutralization assay formats currently in use and the importance of the RSV IS for harmonization of results across formats and across laboratories. It also outlines good practices for key assay components and data analysis to promote the quality and consistency of measuring RSV nAb titers in serum specimens.
