Infection and resistance mechanisms of phage vB_VpM-PP270 in Vibrio parahaemolyticus via capsular polysaccharide

<i>Vibrio parahaemolyticus</i> is a major foodborne pathogen that threatens public health and aquaculture, necessitating alternative biocontrol strategies such as phage therapy. This study introduces phage vB_VpM-PP270, isolated from aquaculture wastewater, and explores its infection mechanism targeting <i>V. parahaemolyticus</i> VP270. The research highlights capsular polysaccharide (CPS) as the primary receptor for phage adsorption and identifies ORF22, a tail spike protein, as the receptor-binding protein. PP270 demonstrates stability across a wide pH range and temperatures, effectively inhibiting VP270 growth in culture and on chilled shrimp. Phage-resistant mutants show mutations in CPS biosynthesis genes, which reduce phage adsorption and promote biofilm formation. These findings provide insights into phage-host interactions and offer a framework for developing phage therapies resilient to resistance, with significant implications for food safety and sustainable aquaculture practices.