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ACE2 : S1 RBD Interaction-Targeted Peptides and Small Molecules as Potential COVID-19 Therapeutics
Lennox Chitsike1, John Krstenansky2, Penelope J Duerksen-Hughes1
1Department of Basic Sciences, Loma Linda University School of Medicine, 11021 Campus Street, 101 Alumni Hall, Loma Linda, CA 92354, USA.
Abstract:
The COVID-19 pandemic that began in late 2019 continues with new challenges arising due to antigenic drift as well as individuals who cannot or choose not to take the vaccine. There is therefore an urgent need for additional therapies that complement vaccines and approved therapies such as antibodies in the fight to end or slow down the pandemic. SARS-CoV-2 initiates invasion of the human target cell through direct contact between the receptor-binding domain of its Spike protein and its cellular receptor, angiotensin-converting enzyme-2 (ACE2). The ACE2 and S1 RBD interaction, therefore, represents an attractive therapeutic intervention to prevent viral entry and spread. In this study, we developed a proximity-based AlphaScreen™ assay that can be utilized to quickly and efficiently screen for inhibitors that perturb the ACE2 : S1 RBD interaction. We then designed several peptides candidates from motifs in ACE2 and S1 RBD that play critical roles in the interaction, with and without modifications to the native sequences. We also assessed the possibility of reprofiling of candidate small molecules that previously have been shown to interfere with the viral entry of SARS-CoV. Using our optimized AlphaScreen™ assay, we evaluated the activity and specificity of these peptides and small molecules in inhibiting the binding of ACE2 : S1 RBD. This screen identified cepharanthine as a promising candidate for development as a SARS-CoV-2 entry inhibitor.
Insights
New therapies are needed to combat COVID-19. Researchers developed an assay to screen for inhibitors of the SARS-CoV-2 Spike protein binding to ACE2, identifying cepharanthine as a potential antiviral drug.
Area of Science:
- Virology
- Drug Discovery
- Biochemistry
Background:
- The COVID-19 pandemic persists due to viral evolution and vaccination challenges.
- New therapeutic strategies are crucial to complement existing vaccines and treatments.
- The interaction between the SARS-CoV-2 Spike protein's receptor-binding domain (RBD) and human ACE2 is essential for viral entry.
Purpose of the Study:
- To develop a high-throughput screening assay to identify inhibitors of the ACE2-S1 RBD interaction.
- To evaluate peptide candidates and repurposed small molecules for their ability to block SARS-CoV-2 entry.
- To identify novel therapeutic agents targeting viral entry mechanisms.
Main Methods:
- Development of a proximity-based AlphaScreen™ assay for screening inhibitors.
- Design and synthesis of peptide candidates based on ACE2 and S1 RBD interaction motifs.
- Repurposing of small molecules previously shown to inhibit SARS-CoV entry.
- Evaluation of identified compounds for their efficacy in inhibiting ACE2:S1 RBD binding.
Main Results:
- An optimized AlphaScreen™ assay was established for efficient screening.
- Several peptide candidates and small molecules were assessed for inhibitory activity.
- Cepharanthine was identified as a potent inhibitor of the ACE2:S1 RBD interaction.
- The specificity and activity of potential inhibitors were confirmed.
Conclusions:
- The developed AlphaScreen™ assay is a valuable tool for identifying SARS-CoV-2 entry inhibitors.
- Cepharanthine shows promise as a novel therapeutic candidate for blocking SARS-CoV-2 viral entry.
- Targeting the ACE2-S1 RBD interaction is a viable strategy for developing new antiviral therapies.
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