Isolation and comprehensive characterization of a novel serotype D-specific lytic phage against Pasteurella multocida.

Abstract

Pasteurella multocida serotype D is a major pathogen responsible for severe respiratory disease in swine, resulting in substantial economic losses worldwide. The increasing prevalence of antimicrobial resistance highlights the urgent need for alternative control strategies. In this study, we report the isolation and comprehensive characterization of a novel, strictly lytic phage, PGG01, that specifically infects P. multocida serotype D. Phage PGG01 is stable over a pH range of 5-9 and at temperatures up to 50 °C, reflecting conditions relevant to swine production environments. Host-range analysis shows its high specificity and potent lytic activity against serotype D strains. One-step growth curve analysis reveals a latent period of approximately 20 min followed by a distinct burst phase, indicating efficient replication dynamics. Whole-genome sequencing demonstrated that PGG01 possesses a 34.7-kb double-stranded DNA genome lacking genes associated with virulence, antibiotic resistance, or lysogeny, supporting its favorable safety profile. Phylogenetic and intergenomic analyses place PGG01 within a distinct evolutionary lineage of virulent P. multocida phages, clearly separated from their temperate counterparts. Collectively, these findings identify PGG01 as a promising and safe biocontrol candidate and provide a foundation for the development of phage-based strategies to control pasteurellosis.