Functional and structural basis of Omicron BA.3.2.1 spike.

BA.3.2.1 spike enhances immune evasion by adopting a stable, closed conformation that limits receptor engagement and masks antibody sites, despite high ACE2 affinity.

• Why it matters: Understanding how spike mutations influence viral fitness and immune escape is crucial for predicting variant spread and guiding vaccine design, especially as new sublineages emerge.
• What they did: Researchers engineered live-attenuated SARS-CoV-2 strains with BA.3.2.1 spike and used cryo-EM to analyze its structure, comparing its infectivity and antibody resistance to other variants.
• The result: BA.3.2.1 outcompetes BA.3 in human airway cells but shows reduced replication compared to some variants, while exhibiting increased resistance to neutralization, explaining its limited prevalence.