Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum

TLDR

SARS‑CoV‑2 variants rapidly become dominant, and the B.1.617.2 lineage, with increased transmissibility, has driven the current wave in India and is classified as a variant of concern in the United Kingdom. The study aims to assess how monoclonal antibodies, convalescent, and vaccine sera neutralize B.1.617.1 and B.1.617.2 and to map the antigenic space of current variants. This assessment is complemented by structural analyses of Fab/RBD complexes to elucidate antibody binding. Neutralization of both B.1.617 variants is reduced relative to ancestral strains, with B.1.351 and P.1 sera showing markedly greater reduction against B.1.617.2, indicating that prior infection with these variants may heighten susceptibility to reinfection and informing future vaccine strategies.

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has undergone progressive change, with variants conferring advantage rapidly becoming dominant lineages, e.g., B.1.617. With apparent increased transmissibility, variant B.1.617.2 has contributed to the current wave of infection ravaging the Indian subcontinent and has been designated a variant of concern in the United Kingdom. Here we study the ability of monoclonal antibodies and convalescent and vaccine sera to neutralize B.1.617.1 and B.1.617.2, complement this with structural analyses of Fab/receptor binding domain (RBD) complexes, and map the antigenic space of current variants. Neutralization of both viruses is reduced compared with ancestral Wuhan-related strains, but there is no evidence of widespread antibody escape as seen with B.1.351. However, B.1.351 and P.1 sera showed markedly more reduction in neutralization of B.1.617.2, suggesting that individuals infected previously by these variants may be more susceptible to reinfection by B.1.617.2. This observation provides important new insights for immunization policy with future variant vaccines in non-immune populations.