Antibody-Bactericidal Macrocyclic Peptide Conjugates To Target Gram-Negative Bacteria

Area of Science:

• Bioconjugation Chemistry
• Antimicrobial Peptide Engineering
• Antibody-Drug Conjugates

Background:

• Antimicrobial infections necessitate novel therapeutic molecules.
• Natural antimicrobial peptides (AMPs) are promising but face challenges like instability and toxicity.
• Existing limitations hinder the clinical development of AMPs.

Purpose of the Study:

• To develop antibody-bactericidal macrocyclic peptide conjugates (ABCs) for targeted antimicrobial therapy.
• To engineer macrocyclic antimicrobial peptides (mAMPs) with improved stability and reduced toxicity.
• To evaluate the efficacy and safety of ABCs against Gram-negative bacteria.

Main Methods:

• Synthesized a library of macrocyclic antimicrobial peptides (>30-mer) using cysteine S_N Ar chemistry.
• Selected mAMP variants for enhanced proteolytic stability and low hemolytic activity.
• Conjugated selected mAMPs to an *Escherichia coli*-targeted monoclonal antibody using sortase A ligation.

Main Results:

• Developed ABCs with significantly minimized hemolytic activity.
• Demonstrated potent *in vitro* bactericidal activity against *E. coli* at nanomolar concentrations.
• Achieved targeted delivery of the macrocyclic peptide payload to Gram-negative bacteria via the antibody.

Conclusions:

• Antibody-fused macrocyclic peptides represent a viable strategy for developing novel antimicrobial agents.
• ABCs overcome key limitations of traditional antimicrobial peptides, offering enhanced stability and specificity.
• This approach holds potential for creating new therapeutics to combat challenging bacterial infections.