Genomic and Biological Characterization of a Broad-Host-Range KVP40-Like Bacteriophage vB_VpM-pA3B5 for Control of AHPND-Causing Vibrio parahaemolyticus

초록

Vibrio parahaemolyticus harboring the pVA1 plasmid (VpAHPND) causes acute hepatopancreatic necrosis disease (AHPND), a major threat to global shrimp aquaculture. Although bacteriophage (phage)-based biocontrol has emerged as a promising alternative to antimicrobial agents for controlling VpAHPND, most studies have focused on disease prevention in culturing shrimp rather than post-harvest applications. In this study, a KVP40-like jumbo phage, designated vB_VpM-pA3B5, was isolated and characterized, and its biocontrol potential was evaluated in both VpAHPND-contaminated shrimp products and shrimp bioassay. Phage vB_VpM-pA3B5 exhibited a broad host range, infecting globally distributed VpAHPND strains, an AHPND-causing V. campbellii strain, and three additional Vibrio species. The phage demonstrated strong lytic activity, efficient replication, and high environmental stability. Genome analysis revealed a 243,570-bp linear dsDNA genome encoding 382 predicted ORFs and 28 tRNAs, with no virulence or antimicrobial resistance genes detected. Comparative genomic analysis indicated high synteny with the Schizotequatrovirus phages KVP40 and PVA8 and identified a unique tail fiber protein (ORF115) that may contribute to its broad host range. In VpAHPND-contaminated shrimp products, the phage efficiently reduced bacterial loads and actively replicated during storage. In the shrimp bioassay, although cumulative mortality was not reduced, phage-treated shrimp exhibited alleviated hepatopancreatic lesions and lower pirA gene loads than the VpAHPND-challenged group. These findings highlight the potential of phage vB_VpM-pA3B5 as a biocontrol agent for mitigating AHPND-associated risks in shrimp aquaculture and reducing the dissemination of VpAHPND through shrimp products.

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