For example in coho salmon humoral antibodies appeared in 25 days and 10 days

For example in coho salmon humoral antibodies

This preview shows page 395 - 397 out of 594 pages.

For example, in coho salmon, humoral antibodies appeared in 25 days and 10 days at water temperatures of 6°C and 18°C, respectively (Groberg, 1982). The poor relative performance of orally administered vaccines has been partially attributed to an inability of the fish to develop humoral antibodies (Fryer et al., 1978; Gould et al, 1978; Kusuda et al, 1978c; Groberg, 1982). However, the role of these antibodies in protection against disease is unclear. Vibrio harveyi Vaccine development programmes aimed at V. harveyi have not been especially successful, although this situation appears to be slowly changing. A whole-cell prep- aration, which was applied to barramundi (Lates calcarifer) by i.p. injection, anal intubation and immersion, led to antibody production, thereby demonstrating that fish could respond to vaccination (Crosbie and Nowak, 2004). By expressing the HLl gene, which encodes the haemolysin from V. harveyi, in yeast (Saccharomyces cere- visiae), the protein (= haemolysin) was expressed on the cell surface and was active against flounder erythrocytes. Moreover, serum from flounder that had received the live modified yeast cells by i.p. injection revealed haemolytic activity. Challenge experiments demonstrated that flounder and turbot were protected soon after
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Control 377 administration of yeast and then exposure to a virulent culture of V. harveyi (Zhu et aL, 2006). A bivalent vaccine (with Ph. damselae subsp. piscicida) based on formalised cells and ECP administered to sole by immersion with booster or by i.p. injection led to high levels of protection (RPS = ~88%) for 4 months, after which the benefit declined (Arijo et al, 2005). Vibrio ordalii The methods discussed for V. anguillarum apply. Likewise with V. anguillarum, the immunogenicity of LPS has been demonstrated (Velji et al, 1990, 1991, 1992). Vibrio salmonicida There has been success with formahsed vaccines for the prophylaxis of Hitra disease. Immersion of Atlantic salmon in these vaccines resulted in protection, even after 6 months (Holm and J0rgensen, 1987). It has emerged that V. salmonicida vaccines exert adjuvant activities on T-dependent and T-independent antigens in salmonids, namely rainbow trout. Essentially, vaccine preparations enhance antibody responses, notably to LPS (Steine et al, 2001). Thus, the inclusion of inactivated V. salmonicida antigens in vaccine preparations may have an overall beneficial effect on the recipient fish (Hoel et ai, 1998b). The incubation temperature used to culture V. salmonicida is an important aspect of vaccine production, with 10°C (this coincides with the upper range of water temperatures at which cold-water vibriosis is most likely to occur) rather than 15°C giving a higher yield of cells in broth media (Colquhoun et ai, 2002). At least one vaccine has been commerciaHsed in a polyvalent form. Vibrio vulnificus A vaccine, coined Vulnivaccine which contains capsular antigens and toxoids (being the best of several alternatives; Collado et ai, 2000) of serovar E, and was adminis- tered by immersion for 1 h in three doses at 12 day intervals, has been evaluated in
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