Computational screening identified 310 cell-penetrating peptide sequences in the SARS-CoV-2 proteome, with 94% predicted non-toxic and potential as drug delivery tools.
310 CPPsdiscovered in the SARS-CoV-2 proteome, with 94% predicted safe for drug delivery applications
What the researchers found
A systematic computational screen of the SARS-CoV-2 proteome identified 310 sequences with cell-penetrating peptide (CPP) characteristics. These SCV2-CPPs spanned regions involved in replication, protein-nucleotide interaction, protein-protein interaction, and complex stabilization.
Safety and practicality analysis: 94.3% were predicted non-toxic. 38% were neither antigenic nor allergenic, important for therapeutic use. 36.7% resisted all four major protease families, meaning they could survive in biological fluids.
Structural analysis: about one-third had sufficient helix or sheet structure for efficient cellular uptake. Among helical CPPs, 44.3% were predicted lipid-binding, important for membrane interaction.
The top candidates for drug delivery were SCV2-CPP118, 119, 122, and 129, all from NSP12 (RNA-dependent RNA polymerase). Cysteine-rich CPPs from the helicase (NSP13) could potentially form cyclic structures in endosomes for better release.
Beyond delivery: 59.6% had predicted antibacterial activity, 29.6% antiviral, 32.3% antifungal, 63.6% immunomodulatory, and 21.9% anticancer properties.
Why it matters
Viruses are nature's experts at getting inside cells. Mining viral proteomes for cell-penetrating peptides converts a pathogen into a source of drug delivery tools. The SARS-CoV-2 proteome had not been screened before. Some identified peptides could serve as delivery vehicles; others might be therapeutic themselves.
The numbers in context
310 CPPs; 94.3% non-toxic; 38% non-antigenic; 36.7% protease-resistant; 4 top candidates from NSP12
How the study worked
Computational study. The entire SARS-CoV-2 proteome was screened using cell-penetrating peptide prediction algorithms. Identified CPPs were analyzed for toxicity, antigenicity, allergenicity, protease resistance, secondary structure, lipid-binding potential, and bioactive properties. Ten experimentally validated viral CPPs from other viruses were used as positive controls to validate the screening pipeline.
Who was studied
SARS-CoV-2 proteome (computational analysis)
What this study cannot tell us
Entirely computational. None of the 310 peptides have been synthesized or experimentally tested for cell penetration, toxicity, or bioactivity. Prediction algorithms have significant false-positive rates. The four top candidates need laboratory validation. In silico protease resistance predictions do not always match real-world degradation.
How to read the evidence
Preliminary evidence — entirely computational. None of the predicted peptides have been experimentally validated for cell penetration or safety.
When this study was published
Published in 2020 during the COVID-19 pandemic. Experimental validation of these candidates may have followed.
The bigger picture
Viruses are nature's experts at entering cells. Mining viral genomes for cell-penetrating peptides converts pathogens into sources of drug delivery tools. This approach could yield delivery vectors with evolved cell-entry capabilities.
Questions still open
- Do any of these 310 predicted CPPs actually penetrate cells when synthesized?
- Could using virus-derived peptides trigger unwanted immune responses?
- Are CPPs from other virus families equally promising?
Common questions
Can virus proteins be safely used as drug delivery tools?
Why search a virus for cell-penetrating peptides?
Read the original research
Decoding the proteome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for cell-penetrating peptides involved in pathogenesis or applicable as drug delivery vectors.
Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 85, 104474
Citation
Hemmati, Shiva; Behzadipour, Yasaman; Haddad, Mahdi. (2020). Decoding the proteome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for cell-penetrating peptides involved in pathogenesis or applicable as drug delivery vectors.. Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, 85, 104474. https://doi.org/10.1016/j.meegid.2020.104474