Molecular study of Yersinia ruckeri distribution, the causative agent of yersiniosis in some farmed rainbow trout of Iran

    Yersinia ruckeri is the causative agent of yersiniosis, one of the most serious bacterial diseases in rainbow trout culture industry with high economic losses. Outbreaks of clinical forms of the disease have been considerable in Iranian rainbow trout farms. This study was aimed to evaluate the molecular epidemiology of yersiniosis caused by Y. ruckeri, affected farmed trout in Mazandaran (22 farms), Tehran (18 farms), Lorestan (6 farms) and Zanjan (6 farms) provinces during 2011to 2013. Furthermore, biotyping and sequencing of the recovered Iranian isolates was performed. Totally, 34 Y. ruckeri isolates were identified in Mazandaran (14 farms), Tehran (17 farms) and Zanjan (3 farms). All isolates were strongly positive in latex bacterial agglutination using monoclonal antibody to Y. ruckeri. Also, all isolates were identified as biotype 1 showing motility and having lipase activity.  In addition, all isolates showed high sequencing similarity (99%). These biochemical, serological and molecular studies all together confirmed the increasing distribution of yersiniosis casued by Y. ruckeri biotype 1 in farmed trout in Iran and so require preventive measures.