Phage engineering strategies to expand host range for controlling antibiotic-resistant pathogens.

Bacteriophages are known as a promising alternative to control rising bacterial resistance. The adsorption phase is critical for the successful infection of phages, as it determines their ability to recognize and attach to specific bacterial host cells. However, their limited host ranges due to narrow host specificity significantly limit their potential applications and overall effectiveness. Receptor-binding proteins (RBPs) are crucial in the recognition process, and modifying these proteins provides a valuable opportunity to broaden host ranges and enhance adsorption rates. Therefore, gaining a more comprehensive understanding of the interactions between phages and their bacterial hosts is essential. To overcome this challenge, various in vivo and in vitro engineering platforms have been developed, including recombineering, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins (Cas) systems, yeast-based technologies, and cell-free systems. These methods provide diverse strategies and flexibility for constructing customized phage genomes with desired characteristics, ultimately enhancing phage application efficiency. This review discusses different types of RBPs in phages and their mechanisms of adsorption, highlighting their relevance for adaptable engineering strategies. We also summarize various phage engineering platforms and explore the design of synthetic phages with expanded host ranges. Finally, we highlight the advantages and limitations of current engineering methods, providing insights to guide future research efforts.