Used in vaccine development and diagnostic assays to study immune response against the Omicron variant of SARS-CoV-2. The A484E mutation helps researchers evaluate antibody neutralization and assess the effectiveness of existing vaccines or therapeutics against this variant. The Fc tag enables easy detection and purification, making it suitable for binding assays, serology tests, and monoclonal antibody screening. Also employed in structural studies to understand spike protein interactions with human ACE2 receptors.