SARS-CoV-2 variant with higher affinity to ACE2 shows reduced sera neutralization susceptibility

Vogel, Monique; Chang, Xinyue; Sousa Augusto, Gilles; Mohsen, Mona O.; Speiser, Daniel E.; Bachmann, Martin F.

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. Objective We aimed to assess how mutations in the SARS-CoV-2 RBD affect receptor affinity to angiotensin-converting enzyme 2 (ACE2) and neutralization by anti-RBD serum antibodies. Methods We produced a SARS-CoV-2 RBD mutant (RBDmut) with key mutations (E484K, K417N, N501Y) from the newly emerged Brazilian variant. Using Biolayer Interferometry, we analyzed the binding of this mutant to ACE2, and the susceptibility to neutralization by sera from vaccinated mice and COVID-19 convalescent patients. Results Kinetic profiles showed increased RBDmut - ACE2 affinity compared to RBDwt, and binding of vaccine-elicited or convalescent sera was significantly reduced. Likewise, both sera types showed significantly reduced ability to block RBDmut - ACE2 binding indicating that antibodies induced by RBDwt have reduced capability to neutralize mutant virus. Conclusion Our physiochemical data show enhanced infectivity and reduced neutralization by polyclonal antibodies of the Brazilian variant of SARS-CoV-2. Capsule summary SARS-CoV-2 variant with Brazilian RBD mutations shows increased ACE2 affinity and reduced susceptibility to blockage by vaccine-elicited and convalescent sera.