Abstract
Background : Several new variants of SARS-CoV-2 have emerged
since fall 2020 which have multiple mutations in the receptor binding
domain (RBD) of the spike protein. It is unclear which mutations affect
receptor affinity versus immune recognition.
Methods: We produced RBD with single mutations (E484K, K417N or
N501Y) or with all three mutations combined and tested their binding to
ACE2 by biolayer interferometry (BLI). The ability of convalescent sera
to recognize RBDs and block their interaction with ACE2 was tested as
well.
Results: We demonstrated that single mutation N501Y increased
binding affinity to ACE2 but did not significantly affect its
recognition by convalescent sera. In contrast, single mutation E484K had
almost no impact on the binding kinetics, but essentially abolished
recognition of RBD by convalescent sera. Interestingly, combining
mutations E484K, K417N and N501Y resulted in a RBD with both features:
enhanced receptor binding and abolished immune recognition.
Conclusions: Our data demonstrate that single mutations either
affect receptor affinity or immune recognition while triple mutant RBDs
combine both features.