Virus Reduction Neutralization Test: A Single-Cell Imaging High-Throughput Virus Neutralization Assay for Dengue

Area of Science:

• Virology
• Immunology
• Assay Development

Background:

• Serum-neutralizing antibodies are key indicators of vaccine immunogenicity and clinical efficacy.
• The plaque/focus reduction neutralization test (P/FRNT) is the current standard but suffers from high variability, poor precision, and long turnaround times.

Purpose of the Study:

• To introduce and evaluate the virus reduction neutralization test (VRNT) as a high-throughput, precise alternative to the P/FRNT.
• To demonstrate the VRNT's improved performance in terms of speed, precision, and throughput.

Main Methods:

• The VRNT utilizes imaging cytometry to count virus-infected cells one day post-infection, unlike the P/FRNT which relies on foci formation.
• The assay uses unaltered wild-type virus and immunostaining, similar to P/FRNT, but with automated cell counting.

Main Results:

• The VRNT demonstrated a 15-fold increase in throughput and reduced assay time compared to P/FRNT.
• VRNT showed lower variability (7-25% coefficient of variation) than P/FRNT, attributed to direct cell counting avoiding foci overlap issues.
• Testing of 81 clinical samples confirmed a positive correlation between VRNT and P/FRNT results.

Conclusions:

• The VRNT is a significant improvement over P/FRNT for neutralization assays, offering enhanced speed, precision, and throughput.
• The VRNT provides a viable, more efficient alternative for assessing neutralizing antibodies, crucial for vaccine development and evaluation.