A virulent phage vB_VpaP_R28Z infecting Vibrio parahaemolyticus with potential for therapeutic application

Vibrio parahaemolyticus, a major foodborne pathogen, contaminates aquatic products and causes significant economic losses in aquaculture while threatening food security and public health. Given the rising prevalence of multidrug-resistant V. parahaemolyticus strains, phage therapy has emerged as an effective and environmentally sustainable alternative for controlling vibriosis in aquaculture. In this study, a virulent bacteriophage, vB_VpaP_R28Z (R28Z), which infects V. parahaemolyticus ATCC 17802^T, was isolated and comprehensively characterized.

R28Z was isolated from sewage collected at a seafood market in southern China and exhibits pronounced lytic properties against pathogenic Vibrio species prevalent in aquaculture environments, including Vibrio parahaemolyticus, Vibrio diabolicus, and Vibrio alginolyticus. Transmission electron microscopy (TEM) analysis revealed that R28Z belongs to the podophage morphotype. Genomic analysis indicated that R28Z is a double-stranded DNA phage with a genome size of 43,284 bp and a G + C content of 49.34%. Notably, no genes associated with lysogeny, virulence, or antibiotic resistance were detected in R28Z, suggesting its suitability for therapeutic applications. R28Z demonstrated high efficacy in lysing host cells, with a short latent period of less than 10 min and a large burst size of 113 ± 19 PFU/cell (average ± s.d.). Additionally, R28Z exhibited stability over a broad pH range of 4-10 and at temperatures ranging from 4 °C to 50 °C. Taxonomic assessments validated the novelty of R28Z, suggesting that it represents a new species of the Maculvirus genus and enriches the diversity of vibriophage candidates for therapeutic interventions against V. parahaemolyticus infections.

The newly discovered phage R28Z, characterized by its high lytic efficiency and environmental stability, represents a novel species as a potential alternative biocontrol agent for managing V. parahaemolyticus infections in aquaculture.