Steric Hindrance of Antibody Binding in Omicron Spike Fusion Intermediate
A recent study published in Nature reveals how the SARS-CoV-2 Omicron variant evades neutralization by antibodies targeting a conserved pan-coronavirus epitope. Researchers utilized cryo-electron microscopy and functional analyses to demonstrate that the antibody 76E1, which targets spike residues 815–825, recognizes an open early fusion intermediate known as the S2′-helix. Omicron variants escape this immune response through steric hindrance caused by shifts in the S2′-helix and restricted distancing between the S1 subunit and ACE2. The H655Y mutation is identified as central to this evasion mechanism, alongside an increased reliance on cathepsin-mediated entry. Crucially, the study found that minimizing the size of the antibody overcomes these physical barriers, restoring access to the target epitope. This modification significantly enhanced neutralizing activity against authentic Omicron variants and other human coronaviruses, including SARS-CoV-1 and HCoV-229E. These findings suggest that developing small-molecule therapies or minimized antibodies targeting the S2′-helix could provide a viable strategy for creating broad-spectrum treatments against current and future coronavirus threats.
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Steric Hindrance of Antibody Binding in Omicron Spike Fusion Intermediate
A recent study published in Nature reveals how the SARS-CoV-2 Omicron variant evades neutralization by antibodies targeting a conserved pan-coronavirus epitope. Researchers utilized cryo-electron microscopy and functional analyses to demonstrate that the antibody 76E1, which targets spike residues 815–825, recognizes an open early fusion intermediate known as the S2′-helix. Omicron variants escape this immune response through steric hindrance caused by shifts in the S2′-helix and restricted distancing between the S1 subunit and ACE2. The H655Y mutation is identified as central to this evasion mechanism, alongside an increased reliance on cathepsin-mediated entry. Crucially, the study found that minimizing the size of the antibody overcomes these physical barriers, restoring access to the target epitope. This modification significantly enhanced neutralizing activity against authentic Omicron variants and other human coronaviruses, including SARS-CoV-1 and HCoV-229E. These findings suggest that developing small-molecule therapies or minimized antibodies targeting the S2′-helix could provide a viable strategy for creating broad-spectrum treatments against current and future coronavirus threats.
Nature