Effects of Mutations in the Receptor-Binding Domain of SARS-CoV-2 Spike on its Binding Affinity to ACE2 and Neutralizing Antibodies Revealed by Computational Analysis

SARS-CoV-2 causing coronavirus disease 2019 (COVID-19) is responsible for one of the most deleterious pandemics of our time. The interaction between the ACE2 receptors at the surface of human cells and the viral Spike (S) protein triggers the infection making the receptor-binding domain (RBD) of the SARS-CoV-2 S-protein a focal target for the neutralizing antibodies (Abs). Despite the recent progress in the development and deployment of vaccines, the emergence of novel variants of SARS-CoV-2 insensitive to Abs produced in response to the vaccine administration and/or monoclonal ones represents upcoming jeopardy. Here, we assessed the possible effects of single and multiple mutations in the RBD of SARS-CoV-2 S-protein on its binding energy to various antibodies and the human ACE2 receptor. The performed computational analysis indicates that while single amino acid replacements in RBD may only cause partial impairment of the Abs binding, moreover, limited to specific epitopes, some variants of SARS-CoV-2 (with as few as 8 mutations), which are already present in the population, may potentially result in a much broader antigenic escape. We also identified a number of point mutations, which, in contrast to the majority of replacements, reduce RBD affinity to various antibodies without affecting its binding to ACE2. Overall, the results provide guidelines for further experimental studies aiming at the identification of the high-risk RBD mutations allowing for an antigenic escape.