Phage Biology

Furunculosis in salmonids is caused by Aeromonas salmonicida, a gram negative, fermentative, rod-shaped species of Aeromonodicae. Since its discovery in 1980, A. salmonicida has often been responsible for the decimation of hatchery salmon and trout. Current methods to combat furunculosis include antibiotics and a vaccine administered via injection. Both methods of defense are problematic as antibiotic resistance has become prevalent and vaccine administration is too labor intensive for hatchery use.

Bacteriophage show promise as a potential alternative for the treatment of furunculosis. A. salmonicida-specific phages were isolated from fish hatcheries and sewage treatment centers in the Pacific Northwest. Those phages with the broadest host range were chosen for further characterization in preparation for developing a therapeutic cocktail. One of them, AEV1, is a new species of myovirus, with a 60 nm isometric head and a 17 x 135 nm tail. About 20% of its 30 kb genome has been sequenced and the genes for several structural proteins identified, including the main capsid, portal, tail fiber and baseplate proteins. However, other regions show no homology with any entry in Genbank.

Some AEV1 structural proteins show homologies with those of known temperate phages, but AEV1 plaques are clear, about 2 mm in size and no evidence for lysogeny has been found. We are further characterizing AEV1 along with several of the other phages and preparing to carry out phage therapy trials in conjunction with Aberdeen High School, the Murdock Foundation, and NW Indian Fisheries.

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Last Updated: May 29, 2008

The Evergreen State College

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Olympia, Washington 98505

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