Oil-adjuvanted fish vaccines

Aeromonas hydrophila is a Gram-negative, facultative anaerobic bacterium known to cause motile aeromonad septicaemia (MAS) in freshwater fish farming. It is also considered a human pathogen. The major adhesin of A. hydrophila, a 43 kDa outer membrane protein, was cloned and expressed by Fang et al. (2004). The molecule was used in a vaccine for the blue 

Flavobacterium psychrophilum is a widespread Gram-negative pathogen in freshwater causing rainbow trout fry syndrome (RTFS) and bacterial cold water disease (BCWD) (Hogfors et al. 2008). In addition to rainbow 

Flavobacterium columnare is a Gram-negative bacterium responsible for columnaris disease. The disease was first described in 1917 in several warmwater fish species from the Mississippi River, and has since been isolated from freshwater fish species worldwide (Grabowski et al. 2004). Specific antibodies were found in tilapia Oreochromis niloticus) plasma and mucus following i.p. injection of formalin-killed sonicated or whole cells of F. columnare in FCA within 2 weeks. After a secondary immunisation the antibody response increased. At 10 weeks post-immunisation the titre remained elevated. In addition, antibodies were observed in the cutaneous mucus of fish that had been i.p. immunised with formalin-kiUed sonicated cells in FCA 6 and 8 weeks post-immunisation (Grabowski et al. 2004). 

The mode of action of mineral oil adjuvant vaccines is complex and includes the initial antibody stimulus resulting from dispersal of antigen, the slow release of antigen and the inflanunatory response (McKinney and Davenport 1961 Jansen et al. 2005). As with FCA, the use of other mineral 

Montanide is a metabolizable oil adjuvant that has been used in both mammalian and fish vaccines (Lawrence et al. 1997 Ravelo et al. 2006). 

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