Engineered phage with cell-penetrating peptides for intracellular bacterial infections.

Salmonella infection poses a critical challenge to global public health, and the situation is exacerbated by the increasing prevalence of antibiotic resistance. Bacteriophages (phages) are increasingly being used as antimicrobial agents due to their ability to kill specific bacteria. However, the low cellular uptake of phages has limited their use in treating intracellular bacterial infections. Here, we present a study using engineered phages with cell-penetrating peptides (CPPs) for enhancing the internalization efficiency of phages to inhibit bacterial intracellular infections. Through bioinformatic analysis, we identified a phage-encoded protein harboring an immunoglobulin-like (Ig-like) domain as the potential target for phage display. Using a CRISPR-Cas9-based method, we successfully displayed short peptides on GP94, an Ig-like domain-containing protein, of Salmonella phage selz. We improved phage intracellular uptake in multiple cell types by fusion of various CPPs to GP94. Notably, the phage selz HA-TAT showed promising results in enhancing the intracellular inhibition of Salmonella in different cells. Our research provides a straightforward strategy for displaying CPPs on non-model phages, offering a promising novel and effective therapeutic approach for treating intracellular and drug-resistant bacteria. IMPORTANCE Salmonella infection is a significant threat to global public health, and the increasing prevalence of antibiotic resistance exacerbates the situation. Therefore, finding new and effective ways to combat this pathogen is essential. Phages are natural predators of bacteria and can be used as an alternative to antibiotics to kill specific bacteria, including drug-resistant strains. One significant limitation of using phages as antimicrobial agents is their low cellular uptake, which limits their effectiveness against intracellular bacterial infections. Therefore, finding ways to enhance phage uptake is crucial. Our study provides a straightforward strategy for displaying cell-penetrating peptides on non-model phages, offering a promising novel and effective therapeutic approach for treating intracellular and drug-resistant bacteria. This approach has the potential to address the global challenge of antibiotic resistance and improve public health outcomes.