Beyond the Mutation Abyss: Revisiting SARS-CoV-2 Receptor-Binding Domain Evolution from ACE2 Binding Optimization to...

Area of Science:

• Virology
• Immunology
• Structural Biology

Background:

• The SARS-CoV-2 Omicron variant exhibits numerous spike mutations, maintaining transmissibility while evading humoral immunity.
• Understanding compensatory mechanisms is crucial for predicting viral evolution and designing effective countermeasures.

Purpose of the Study:

• To analyze the evolutionary strategies of SARS-CoV-2 variants, focusing on the receptor-binding domain (RBD).
• To investigate the impact of mutations on B-cell and T-cell epitope conservation and binding affinity.
• To evaluate the role of epistatic interactions in enabling antigenic drift.

Main Methods:

• Systems-virology framework integrating sequence analysis, physicochemical profiling, and epitope mapping.
• Molecular dynamics and MM-PBSA simulations to assess binding energetics.
• Deep mutational scanning (DMS) for benchmarking and analysis of mutation tolerance.

Main Results:

• B-cell epitope conservation significantly decreased in Omicron and its descendants, correlating with increased breakthrough infections.
• RBD T-cell epitopes remained highly conserved across variants.
• Omicron demonstrated compensatory interactions at the ACE2 interface and increased epistatic buffering, allowing extensive antigenic change without compromising structural integrity.

Conclusions:

• SARS-CoV-2 employs a multi-objective evolutionary strategy involving epitope erosion, interface rewiring, and epistatic compensation.
• Conserved T-cell epitopes represent a potential target for broadly protective vaccines.
• These findings can guide surveillance of emerging lineages and inform rational vaccine design.