Bacteriophages as vaccine platforms: Opportunities and challenges in translation.

Bacteriophages (phages) have recently received increased interest as versatile candidates for vaccine development. Their inherent characteristics, such as ease of genetic manipulation, high-density antigen display, intrinsic immunostimulatory properties, demonstrated human safety, and scalability in bacterial hosts, make them attractive as next-generation vaccine platforms. Additionally, their cost-effective production, stability, and existing regulatory approval for food and compassionate phage therapy provide a strong foundation for further development of phage-based vaccines. This commentary summarizes the types of phages, the strategies used, and current advances in phage-based vaccine development for viral and bacterial targets, and discusses the promises and challenges of this platform for novel vaccine development. Phage-based vaccines represent an innovative and promising platform for vaccine development to address significant medical and public health challenges, particularly in antimicrobial resistance, pandemic preparedness, and One Health. Accumulative experimental data have demonstrated that phage-based vaccines induce specific cellular, humoral, and mucosal immune responses at magnitudes comparable to those induced by other vaccine platforms. However, a better understanding of phage biology (interactions with the human immune system and microbiome), more carefully designed preclinical studies, Good Manufacturing Practice production development, the regulatory framework, and ultimately clinical trials are needed before the full potential of this platform is realized.