The effects of inactivation methods of Yersinia ruckeri on the efficacy of single dip vaccination in Atlantic salmon (Salmo salar)

Yersinia ruckeri causes significant losses in farmed salmonids (Tobback et al., 2009) and is the causative agent of both enteric red mouth disease in rainbow trout in the Northern Hemisphere (Tobback et al., 2009) and yersiniosis in Atlantic salmon (Salmo salar) in the Southern Hemisphere (Carson & Wilson, 2009). The first commercial yersiniosis vaccine was licensed in 1976 as formalin-killed whole cells of Y. ruckeri (see Bridle, Koop, & Nowak, 2012). Formalin inactivation is most commonly used for commercial fish vaccine production (Sommerset, Krossøy, Biering, & Frost, 2005). Inactivation of bacteria by formalin influences the physicochemical characteristics of surface antigens and may reduce protective efficacy against pathogenic bacteria (Tu, Chu, Zhuang, & Lu, 2010).