A quadri-fluorescence SARS-CoV-2 pseudovirus system for efficient antigenic characterization of multiple circulating...

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• The continuous emergence of SARS-CoV-2 variants necessitates robust methods for assessing immune responses.
• Evaluating neutralizing antibodies (nAbs) against diverse strains is critical for vaccine development and public health strategies.

Purpose of the Study:

• To develop and validate a high-throughput quadri-fluorescence (qFluo) pseudovirus platform for simultaneous nAb measurement against multiple SARS-CoV-2 variants.
• To assess the immunogenicity and cross-neutralization capabilities of SARS-CoV-2 variants, including XBB.1.5, BA.5, BQ.1.1, and CH.1.1.

Main Methods:

• Development of a qFluo pseudovirus system utilizing four distinct fluorescent reporters for multiplexed nAb detection.
• Validation of the qFluo platform by comparing results with classical single-reporter assays using monoclonal antibodies and human plasma.
• Assessment of hamster immune responses to SARS-CoV-2 spike proteins (BA.5, BQ.1.1, XBB.1.5, CH.1.1) and subsequent cross-neutralization assays against 51 variants.

Main Results:

• The qFluo platform demonstrated high concordance with traditional methods, enabling simultaneous assessment of nAbs against four variants.
• Hamster immunization studies revealed that the XBB.1.5 spike protein conferred superior protective immunity.
• Cross-neutralization analysis showed XBB.1.5 provided enhanced protection against prevalent strains like "FLip" and JN.1 compared to BA.5.

Conclusions:

• The qFluo pseudovirus system offers an efficient tool for evaluating immune responses against multiple SARS-CoV-2 variants.
• XBB.1.5 exhibits strong immunogenic potential and broad cross-neutralization, particularly against currently dominant strains.
• These findings support informed vaccine-strain selection and provide insights into SARS-CoV-2 evolution.