A newly emerging bacterial pathogen caused outbreaks of rainbow trout worldwide and phage therapy

Abstract

This study was conducted to isolate the pathogens and to screen the bacteriophage (phage) for therapeutic application. A total of 36 W. ceti strains were isolated successfully from the diseased fish and confirmed by biochemical tests, 16S rRNA and PCR assay. Herein, in the first time, the Pwr-1 phase was screened and isolated successfully, which is a novel virulent bacteriophage pathogen as a good candidate for therapeutic application. The phage belonged to the family of Siphoviridae, possessed an isometric head approximately 65nm in diameter and a flexible, non-contractile tail of 170-180 nm in length. Latent time and burst size of phage was about 25 min and 16 PFU/ infected cell, respectively. Phage exhibited to be relatively stable with wide range of pH and temperature. Phage had wide host range, lysed all 36/36 tested W. ceti strains. This is the first study to investigate a virulent bacteriophage of newly emerging pathogen infecting rainbow trout with various features making it become a highly potential agent for the therapeutic application in the future alternatives for antibiotic uses.