Design and biological activities of novel inhibitory peptides for SARS-CoV spike protein and angiotensin-converting enzyme 2 interaction.

Severe acute respiratory syndrome (SARS) is an emerging infectious disease caused by a novel coronavirus (SARS-CoV). The binding of SARS-CoV spike (S) protein to cellular angiotensin-converting enzyme 2 (ACE2) is the first step in SARS-CoV infection. Therefore, we assayed the inhibitory effects of small peptides derived from S protein on the binding of S protein to ACE2 and on the S-protein-pseudotyped retrovirus infectivity. SP-4 (residues 192-203), SP-8 (residues 483-494), and SP-10 (residues 668-679) significantly blocked the interaction between S protein and ACE2 by biotinylated enzyme-linked immunosorbent assay, with IC(50) values of 4.30 +/- 2.18, 6.99 +/- 0.71, and 1.88 +/- 0.52 nmol, respectively. Peptide scanning suggested the region spanning residues 660-683 might act as a receptor-binding domain. SP-10 blocked both binding of the S protein and infectivity of S protein-pseudotyped retrovirus to Vero E6 cells. In conclusion, this is the first report of small peptides designed to disrupt the binding of SARS-CoV S protein to ACE2. Our findings suggest that SP-10 may be developed as an anti-SARS-CoV agent for the treatment of SARS-CoV infection.