Aeromonas salmonicida subsp. salmonicida A449

Aeromonas salmonicida has been recognized as a pathogen of fish for over 100 years. In 1894 Emmerich and Weibel made the first report of its isolation during a disease outbreak at a Bavarian brown trout hatchery. The manifestations of the disease include furuncle-like swelling and, at a later stage, ulcerative lesions on infected trout. Since that time a number of subspecies of Aeromonas salmonicida have been recognized, although the taxonomy of the species is far from settled. While Aeromonas salmonicida was traditionally thought of as a pathogen of salmonids, global reports now confirm that this pathogen has been associated with clinical or covert disease in a variety of salmonid and non-salmonid species in freshwater, brackish water and sea water. Aeromonas salmonicida (strain A449) was isolated from a brown trout in the Eure River, France in 1975 and harbors one chromosome and 5 plasmids. Comparison to the related A.hydrophilia ATCC 7966 (AERHH) show the presence of numerous insertion sequence, some of which are still active and various other mobile elements lreading to substantial genome rearrangements. A.salmonicida is no longer mobile and has also recently lost a type IV and type VI secretion systems, thus probably avoiding the host immune system. It seems to be undergoing genome decay and adaptation to its specific host (adapted from PMID 18801193). (HAMAP: AERS4)