Developing Pseudovirus-Based Neutralization Assay against Omicron-Included SARS-CoV-2 Variants.

Area of Science:

• Virology
• Immunology
• Infectious Diseases

Background:

• The global spread of SARS-CoV-2 and its variants, particularly Omicron, presents ongoing challenges to public health.
• In vitro neutralization assays are crucial for assessing the efficacy of vaccines, antibodies, and antiviral therapies against emerging viral strains.

Purpose of the Study:

• To establish and validate a reliable pseudovirus-based neutralization assay for evaluating SARS-CoV-2 variants, including Omicron.
• To assess the neutralization capabilities of monoclonal antibodies and convalescent plasma against various SARS-CoV-2 variants.

Main Methods:

• Development of a pseudovirus system using an HIV-1 backbone with SARS-CoV-2 spike proteins from different variants (Alpha, Beta, Gamma, Kappa, Omicron).
• Optimization of pseudovirus packaging parameters, including plasmid ratios and collection times.
• Validation of the assay using approved monoclonal antibodies and testing of convalescent plasma.

Main Results:

• The assay successfully characterized neutralization against multiple SARS-CoV-2 variants.
• Omicron demonstrated immune evasion, escaping neutralization by certain antibodies (REGN10987, REGN10933) while showing reduced susceptibility to others (S309, ADG-2).
• Convalescent plasma showed reduced neutralizing capacity against Omicron, confirming its immune evasion properties.

Conclusions:

• A practical and safe pseudovirus neutralization assay for SARS-CoV-2 variants has been established, suitable for biosafety level-2 conditions.
• This assay is a valuable tool for characterizing the efficacy of vaccines and therapeutics against current and future SARS-CoV-2 variants, including Omicron.