Genomic, Evolutionary and Phenotypic Insights into Pseudomonas Phage Adele, a Novel Pakpunavirus with Potential for Phage Therapy

Bacteriophages are powerful drivers of microbial evolution and are increasingly explored as alternatives to antibiotics against multidrug-resistant pathogens such as <i>Pseudomonas aeruginosa</i>. Here, we describe the isolation, phenotypic characterization and genomic, structural and evolutionary analysis of <i>Pseudomonas</i> phage Adele, a lytic myovirus representing a novel species within the genus <i>Pakpunavirus</i> (family <i>Vandenendeviridae</i>). Phage Adele exhibits a short latent period of 20 min, a burst size of 59 ± 11 virions per infected cell and a high virulence index, efficiently lysing non-O11 <i>Pseudomonas aeruginosa</i> strains and reducing biofilm biomass. In vivo, Adele confers marked protection in a <i>Galleria mellonella</i> infection model. Phylogenetic reconstruction, synteny analysis and structural modeling demonstrate the relatedness of <i>Vandenendeviridae</i> to phages of the <i>Andersonviridae</i> and <i>Vequintavirinae</i> clades, pointing to a stable, ancestral virion architecture that has undergone lineage-specific elaborations, including the duplication and divergence of tail tube proteins. The tail assembly chaperone gene employs a conserved -1 programmed ribosomal frameshift. Phage Adele encodes an elaborate set of metabolic reprogramming and anti-defense systems, reflecting extensive horizontal gene transfer. The combination of a conserved structural architecture and mosaic genome establishes Adele as an exemplary system for studying modular evolution in phages, alongside its demonstrated therapeutic efficacy.