title: Comparative genomic analysis of bacteriophages specific to the channel catfish pathogen Edwardsiella ictaluri.
abstract: BACKGROUND
  The bacterial pathogen Edwardsiella ictaluri is a primary cause of mortality in channel catfish raised commercially in aquaculture farms. Additional treatment and diagnostic regimes are needed for this enteric pathogen, motivating the discovery and characterization of bacteriophages specific to E. ictaluri.
  
  
  RESULTS
  The genomes of three Edwardsiella ictaluri-specific bacteriophages isolated from geographically distant aquaculture ponds, at different times, were sequenced and analyzed. The genomes for phages eiAU, eiDWF, and eiMSLS are 42.80 kbp, 42.12 kbp, and 42.69 kbp, respectively, and are greater than 95% identical to each other at the nucleotide level. Nucleotide differences were mostly observed in non-coding regions and in structural proteins, with significant variability in the sequences of putative tail fiber proteins. The genome organization of these phages exhibit a pattern shared by other Siphoviridae.
  
  
  CONCLUSIONS
  These E. ictaluri-specific phage genomes reveal considerable conservation of genomic architecture and sequence identity, even with considerable temporal and spatial divergence in their isolation. Their genomic homogeneity is similarly observed among E. ictaluri bacterial isolates. The genomic analysis of these phages supports the conclusion that these are virulent phages, lacking the capacity for lysogeny or expression of virulence genes. This study contributes to our knowledge of phage genomic diversity and facilitates studies on the diagnostic and therapeutic applications of these phages.
authors.affiliation: Department of Fisheries and Allied Aquaculture, Auburn University, USA.
authors.forename: Abel
authors.initials: A
authors.lastname: Carrias
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Welch
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Waldbieser
authors.forename: David A
authors.initials: DA
authors.lastname: Mead
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Terhune
authors.forename: Mark R
authors.initials: MR
authors.lastname: Liles
mesh_terms: D000818:Animals; D001435:Bacteriophages / Q000145:classification* / Q000235:genetics*; D019295:Computational Biology; D020610:Edwardsiella ictaluri / Q000821:virology*; D016679:Genome, Viral / Q000235:genetics*; D007059:Ictaluridae / Q000382:microbiology; D016366:Open Reading Frames; D010802:Phylogeny; D016415:Sequence Alignment; D014764:Viral Proteins / Q000235:genetics
chemical_list: D014764:Viral Proteins