Bacteriophages as Therapeutic and Biotechnological Agents: Host Interactions, Immune Modulation, and Engineering Strategies

Bacteriophages, viruses that specifically infect bacteria, emerge as precision tools to combat multidrug-resistant infections and modulate host immunity. This review explores the dynamic interactions between bacteriophages and both bacterial and eukaryotic hosts, emphasizing their therapeutic potential and biotechnological applications. We discuss mechanisms of phage entry into mammalian tissues, including traversal of the blood–brain barrier, and their roles in shaping innate and adaptive immune responses. The review also highlights advances in phage engineering, such as non-lytic phagemid systems, clustered regularly interspersed short palindromic repeats (CRISPR)-based antimicrobials, and quorum-sensing disruption strategies. These innovations position bacteriophages as versatile agents in modern microbiology, with implications for personalized medicine, immunotherapy, and synthetic biology.