Peptides Corresponding to the Receptor-Binding Domain (RBD) of Several SARS-CoV-2 Variants Of Concern Prevent...

New strategies are needed to prevent and control upcoming outbreaks of SARS-CoV-2 infections, independent of vaccination. SARS-CoV-2 binds to the human ACE-2 receptor through the receptor binding domain (RBD) of the spike (S) protein, allowing the virus to enter human cells and begin replication. When peptides corresponding to four regions of RBD containing previously reported ACE-2 interaction sites were explored, the sequence 392 to 421, peptide p392wt, bound strongly to ACE-2 and inhibited wild-type RBD binding to ACE-2. Interestingly, p392 peptides corresponding to mutated sequences from different SARS-CoV-2 VOCs, including the current VOC BA.5 and KP.3, bound less strongly to ACE-2, but showed partially better inhibition of the ACE-2 interaction of all tested RBDs. When studied in a SARS-CoV-2 pseudovirus assay, the p392 peptides showed a good inhibition rate of 98.8±8.1 % at a peptide concentration of ~244 μmol/L, while none of the p392 peptides inhibited antibody binding to the RBD, suggesting that peptide treatment is sufficient in the presence of anti-RBD antibodies. Interestingly these peptides were active in the presence of diluted human serum and non-toxic to human cell lines.