Genomic characterization of JG068, a novel virulent podovirus active against Burkholderia cenocepacia

AbstractBackgroundAs is true for many other antibiotic-resistant Gram-negative pathogens, members of theBurkholderia cepaciacomplex (BCC) are currently being assessed for their susceptibility to phage therapy as an antimicrobial treatment. The objective of this study was to perform genomic and limited functional characterization of the novel BCC phage JG068 (vB_BceP_JG068).ResultsJG068 is a podovirus that forms large, clear plaques onBurkholderia cenocepaciaK56-2. Host range analysis indicates that this phage can infect environmental, clinical, and epidemic isolates ofBurkholderia multivorans,B. cenocepacia,Burkholderia stabilis, andBurkholderia dolosa, likely through interaction with the host lipopolysaccharide as a receptor. The JG068 chromosome is 41,604 base pairs (bp) in length and is flanked by 216 bp short direct terminal repeats. Gene expression originates from both host and phage promoters and is in the forward direction for all 49 open reading frames. The genome sequence shows similarity toRalstoniaphage ϕRSB1,Caulobacterphage Cd1, and uncharacterized genetic loci of blood disease bacterium R229 andBurkholderia pseudomallei1710b. CoreGenesUniqueGenes analysis indicates that JG068 belongs to theAutographivirinaesubfamily and ϕKMV-like phages genus. Modules within the genome encode proteins involved in DNA-binding, morphogenesis, and lysis, but none associated with pathogenicity or lysogeny. Similar to the signal-arrest-release (SAR) endolysin of ϕKMV, inducible expression of the JG068 SAR endolysin causes lysis ofEscherichia colithat is dependent on the presence of an N-terminal signal sequence. In anin vivoassay using theGalleria mellonellainfection model, treatment ofB. cenocepaciaK56-2-infected larvae with JG068 results in a significant increase in larval survival.ConclusionsAs JG068 has a broad host range, does not encode virulence factors, is obligately lytic, and has activity against an epidemicB. cenocepaciastrainin vivo, this phage is a highly promising candidate for BCC phage therapy development.