Reduced sensitivity of SARS-CoV-2 mutant delta to antibody neutralization

Planas, D., Veyer, D., Baidaliuk, A., etal . Reduced susceptibility of the SARS-CoV-2 mutant delta to antibody neutralization. Nature (2021). https://doi.org/10.1038/s41586-021-03777-9

Commentary

This study shows that the SARS-CoV-2 B.1.617 lineage was identified in India in October 2020 and that the lineage contains three major subtypes (B1.617.1, B.1.617.2, and B.1.617.3) with diverse N-terminal domain (NTD) and receptor binding domain (RBD) There are diverse spike mutations in the NTD and RBD.

B.1.617.2, also called variant Delta, is thought to spread faster than the other variants, and we isolated an infectious Delta strain from a traveler returning from India. We compared the Delta strain to other virus strains and investigated its susceptibility to monoclonal antibodies (mAb) and to antibodies present in the sera of individuals and vaccine recipients during COVID-19 recovery.

Variant delta was found to be resistant to neutralization by several anti-NTD and anti-RBD mAbs, including bamranibimab with impaired binding to the spike, and sera from convalescent patients collected up to 12 months after symptoms were found to be one-fourth as potent against variant delta as compared to variant alpha (B.1.1.7). (B.1.1.7) compared to variant alfa (B.1.1.7) and found to be one-fourth as potent against

Sera from individuals who received one dose of Pfizer or AstraZeneca vaccine showed little inhibition of variant delta, and two doses produced a neutralizing response in 95% of individuals, with titers three to five times lower against delta than against alpha.

These results suggest that variant delta spreads are associated with escape to antibodies targeting non-RBD and RBD spike epitopes.