DEVELOPMENT OF A SPECIFIC BIOTINYLATED DNA-PROBE FOR THE DETECTION OFRENIBACTERIUM-SALMONINARUM

A specific DNA probe for the identification of Renibacterium salmonina rum, the causative agent of bacterial kidney disease (BKD), was develo ped from one of 3 clones pRS47, pRS49, and pRS26 of 5.1 kb, 5.3 kb, an d 11.3 kb, respectively. The biotinylated pRS47/BamHI insert probe was tested on 3 dilutions of DNA extracted from 3 strains of R. salmonina rum and from 1 strain each of Arthrobacter protophormiae, Aeromonas sa lmonicida, Corynebacterium aquaticum, Carnobacterium piscicola, Liston ella anguillarum, Micrococcus luteus, Pseudomonas fluorescens, Vibrio ordalii, and Yersinia ruckeri. In a dot blot assay, this probe hybridi zed only with the DNA from the R. salmoninarum strains. When used on k idney samples from fish challenged with R. salmoninarum, the dot blot hybridization assay with the probe was found to be as sensitive as cul ture. In a fluorescent antibody test, samples that were negative in cu lture and dot blot hybridization showed no more than one fluorescing c ell in 50 microscopic fields examined. This DNA probe, therefore, has the potential for use in the diagnosis of BKD of fish.