title: Use of bioluminescence mutant screening for identification of Edwardsiella ictaluri genes involved in channel catfish (Ictalurus punctatus) skin colonization.
abstract: Initial invasion of the host is the first and vital part of any infection process. We have demonstrated that Edwardsiella ictaluri is capable of colonizing and penetrating catfish skin. Therefore, a mutant library was constructed by random insertion of the Mar2xT7 transposon into the chromosome of E. ictaluri harboring the bioluminescence plasmid pAKgfplux1. This library was then screened through a series of three consecutive challenges for mutants showing a decreased ability to colonize the catfish epithelium. Eighteen mutants were identified that have decreased adhesion and virulence. Mutated genes encoded one sensor protein, two transport proteins, five enzymes, two regulatory proteins, and five hypothetical proteins. Among the mutated genes, the first one identified was a gene encoding for RstA/B, which is known to play a role in regulating the expression of invasion genes in Salmonella enterica Typhimurium. Another mutant was lacking a putative ribonuclease similar to a Shigella protein that regulates the expression of adhesin. A third mutant was defective in a protein similar to a Brucella protein that was initially identified as a transporter, but actually is a member of a newly discovered adhesin family. Results from this study could enable development of a new strategy for blocking E. ictaluri invasion at the initial adherence stage.
authors.affiliation: Clinical Division of Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinaerplatz 1, Vienna 1210, Austria.
authors.forename: Simon
authors.initials: S
authors.lastname: Menanteau-Ledouble
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA. Electronic address: lawrence@cvm.msstate.edu.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Lawrence
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics; D020610:Edwardsiella ictaluri / Q000235:genetics* / Q000472:pathogenicity; D004756:Enterobacteriaceae Infections / Q000382:microbiology* / Q000517:prevention & control; D005393:Fish Diseases / Q000382:microbiology*; D007059:Ictaluridae / Q000382:microbiology*; D008163:Luminescent Measurements / Q000379:methods; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics; D012867:Skin / Q000382:microbiology*; D014774:Virulence