In vitro and in vivo investigation of the antimicrobial and antiviral properties of CLEC3A-derived peptides.

• Applicant: Professor Dr. Andreas Klatt
• Subject Area: Toxicology, Laboratory Medicine
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527884186

We investigated the antimicrobial properties of the C-type lectin domain family 3 member A (CLEC3A) – derived peptides. We identified two peptides (HT-16, HT-47) that kill P.aeruginosa and S.aureus and characterized their killing mechanism. Furthermore, coating plates made of commonly used prosthetic material - titanium - with HT-47 lead to a significantly decreased bacterial adhesion to the plates. By exchanging specific amino acids of HT-16 and HT-47 we were able to boost antimicrobial activity against MRSA und decrease toxicity against eukarotic cells. In addition, we plan to investigate the biostability of CLEC3A-derived peptides as well as potential antimicrobial resistance of the above-mentioned bacterial stems toward the peptides. A lot of this research in recent years showed promising antimicrobial activity in vitro, which were unfortunately not replicable in vivo. We will therefore test the antimicrobial activity of two CLEC3A-derived peptides using three different mouse models: a wound-infection mouse model, a biomaterial-associated infection mouse model and a sepsis mouse model. The animal research proposal for all three models have already been approved by The Ministry for Environment, Agriculture, Conservation and Consumer Protection of the State of North Rhine-Westphalia. Using surface plasmon resonance and electron microscopy, we demonstrate binding of HT-47 to the SARS-CoV-2 spike protein. Our experiments show similar KD-values between HT-47 and the reference AMP LL-37. LL-37, in addition, inhibits the binding of the spike protein on the hACE2 receptor. We postulate, therefore, that HT-47 is also likely to inhibit this binding. Moreover, recent research could show prophylactic and therapeutic effects of LL-37 against a SARS-Cov-2 infection. We plan to characterize the “broadband” binding mechanism of CLEC3A-derived peptides and proteins. A Pseudovirus assay will show whether CLEC3A-derived peptides and proteins inhibit cell infection. Proving the antiviral activity of CLEC3A-peptides could not only lead to novel therapeutical aspects against COVID-19, but also against other viral diseases.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Thomas Streichert