Nanoparticle-Supported, Rapid, Digital Quantification of Neutralizing Antibodies Against SARS-CoV-2 Variants

Area of Science:

• Biotechnology
• Immunology
• Nanotechnology

Background:

• Measuring neutralizing immune responses is crucial due to viral evolution and immune variability.
• Existing neutralizing antibody (nAb) assays often require extensive biosafety measures, complex equipment, and lengthy detection periods.

Purpose of the Study:

• To develop a rapid, nanoparticle-based electronic detection assay (NasRED) for assessing the neutralizing potency of monoclonal antibodies (mAbs) against SARS-CoV-2.
• To demonstrate the assay's ability to differentiate between SARS-CoV-2 variants.

Main Methods:

• Gold nanoparticles (AuNPs) coated with human angiotensin-converting enzyme 2 (ACE2) were used as reporters.
• AuNPs were mixed with mAbs and streptavidin-conjugated SARS-CoV-2 spike (S) protein or receptor binding domains (RBD).
• Changes in AuNP aggregation and optical extinction, measured by a semiconductor system, indicated nAb presence and potency.

Main Results:

• The NasRED assay successfully quantified nAb potency against SARS-CoV-2.
• The assay differentiated between neutralizing antibodies targeting different SARS-CoV-2 variants (Wuhan-Hu-1, Gamma, Omicron).
• The detection time was less than 30 minutes.

Conclusions:

• The nanoparticle-supported, rapid, electronic detection (NasRED) assay provides a fast, portable, and inexpensive method for measuring neutralizing antibody potency.
• This assay is applicable for assessing vaccine efficacy, immune responses to infection, and antibody-based therapy effectiveness.
• The modular design and rapid readout system offer a significant advancement over traditional nAb assays.