COVID-19 variants that escape vaccine immunity: Global and Indian context-are more vaccines needed?

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• The COVID-19 pandemic caused by SARS-CoV-2 has led to millions of deaths globally.
• The viral spike (S) protein, particularly its Receptor Binding Motif (RBM), is a key target for vaccine development due to its role in cell entry via the ACE2 receptor.
• Initial vaccines utilizing a stabilized S protein demonstrated high efficacy (80-95%).

Purpose of the Study:

• To review current vaccine efficacy against SARS-CoV-2 variants.
• To analyze the impact of mutations on the ACE2-S protein complex.
• To provide insights for developing next-generation vaccine antigens effective against evolving SARS-CoV-2 strains.

Main Methods:

• Review of existing data on SARS-CoV-2 vaccines and their neutralizing efficacy.
• Analysis of mutations in viral variants using cryo-electron microscopy (cryo-EM) structural data of the ACE2-S complex.
• Docking simulations to observe mutation effects on the ACE2-S interaction.

Main Results:

• SARS-CoV-2 variants have emerged due to viral RNA mutations and selection pressures, contributing to global infection waves.
• Mutations predominantly affect the S1 domain, specifically the N-terminal domain (NTD) and RBM, as well as the S1-S2 subunit junction.
• Structural analysis indicates these mutations are under selection pressure, potentially altering S protein binding to ACE2.

Conclusions:

• Viral evolution necessitates continuous monitoring of vaccine efficacy against emerging SARS-CoV-2 variants.
• Understanding mutation hotspots in the S1 domain is crucial for designing variant-proof vaccine candidates.
• This review serves as a reference for future antigen design to improve vaccine effectiveness against diverse viral strains.