Biomol Ther.  2021 May;29(3):282-289. 10.4062/biomolther.2020.201.

Discovery of New Fusion Inhibitor Peptides against SARS-CoV-2 by Targeting the Spike S2 Subunit

  • 1Department of Biomedical Sciences, College of Veterinary Medicine, King Faisal University, Al-Ahsa 31982, Saudi Arabia
  • 2Department of Pharmacology, Faculty of Veterinary Medicine, Kafrelsheikh University, Kafrelsheikh 33516, Egypt
  • 3Research Center for Asian Infectious Diseases, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
  • 4Department of Virology, Toyama Institute of Health, Toyama 939-0363, Japan
  • 5Division of Molecular Virology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
  • 6Department of Microbiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea
  • 7Senior Professor Office, The University of Tokyo, Tokyo 108-8639, Japan


A novel coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), caused a worldwide pandemic. Our aim in this study is to produce new fusion inhibitors against SARS-CoV-2, which can be the basis for developing new antiviral drugs. The fusion core comprising the heptad repeat domains (HR1 and HR2) of SARS-CoV-2 spike (S) were used to design the peptides. A total of twelve peptides were generated, comprising a short or truncated 24-mer (peptide #1), a long 36-mer peptide (peptide #2), and ten peptide #2 analogs. In contrast to SARS-CoV, SARS-CoV-2 S-mediated cell-cell fusion cannot be inhibited with a minimal length, 24-mer peptide. Peptide #2 demonstrated potent inhibition of SARS-CoV-2 S-mediated cell-cell fusion at 1 µM concentration. Three peptide #2 analogs showed IC50 values in the low micromolar range (4.7-9.8 µM). Peptide #2 inhibited the SARSCoV-2 pseudovirus assay at IC50=1.49 µM. Given their potent inhibition of viral activity and safety and lack of cytotoxicity, these peptides provide an attractive avenue for the development of new prophylactic and therapeutic agents against SARS-CoV-2.


SARS-CoV-2; COVID-19; Fusion inhibitors; Antiviral drugs
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