UC San Diego

Antimicrobial resistance is a global health threat that is exacerbated by the overuse and misuse of antibiotics in medicine and agriculture. As an alternative to conventional antimicrobial drugs, phage therapy involves the treatment of infected patients with a bacteriophage that naturally destroys bacterial pathogens. With the re-emergence of phage therapy, novel tools are needed to study phages. In this work we set out to screen and isolate peptide candidates that bind to phages and act as affinity tags. Such peptides functionalized with an imaging agent could serves as versatile tools for tracking and imaging of phages. Specifically, we screened a phage display library for peptides that bind to the Good Vibes phage (GV), which lyses the bacterial pathogen Pseudomonas aeruginosa. Isolated monoclonal library phages featured a highly conserved consensus motif, LPPIXRX. The corresponding peptide WDLPPIGRLSGN was synthesized with a GGGSK linker and conjugated to cyanine 5 or biotin. The specific binding of the LPPIXRX motif to GV in vitro was confirmed using an enzyme-linked immunosorbent assay. We demonstrated imaging and tracking of GV in bacterial populations using the fluorescent targeting peptide and flow cytometry. In conclusion, we developed fluorescent labeled peptides that can bind to bacteriophage GV specifically, which may enable real-time analysis of phage in vivo and monitor the efficacy of phage therapy.