Vaccination trials of sea bass, Dicentrarchus labrax (L.), against Photobacterium damsela subsp. piscicida, using novel vaccine mixtures

Abstract

Bacterial cells of the marine fish pathogen Photobacterium damsela subsp. piscicida were grown in novel culture media. A mixture of whole cells and extracellular components was inactivated and used in bath, intraperitoneal (i.p.) and oral vaccination of sea bass, Dicentrarchus labrax, employing two sizes of fish. A commercial vaccine was used for comparative purposes. Control and immunized fish were either bath or intraperitoneally challenged 6 and 12 weeks post-vaccination. Small fish had significantly higher relative percentage survival with the novel vaccine mixture both at 6 and 12 weeks post-vaccination by bath, in comparison with the commercial vaccine. No protection was afforded at 6 or 12 weeks post-immunization by either vaccine after challenge via i.p. injection. Sea bass (1.5-2 g) intraperitoneally vaccinated with various adjuvanted vaccine mixtures were not protected against pasteurellosis. In contrast, larger sea bass (20 g) benefited from vaccination with the novel vaccine mixtures. Intraperitoneal challenge with the pathogen resulted in protection in both fish groups vaccinated with novel vaccine mixtures, whereas control fish suffered high mortalities (> 80%). Orally vaccinated fish were immersion challenged with the pathogen. At 6 and 12 weeks post-vaccination the control fish had a high mortality and the fish vaccinated with the novel vaccine mixture achieved good protection.

Effect of chemotherapy, vaccines and immunostimulants on innate immunity of goldfish infected with Aeromonas hydrophila

“…The survival rate of infected fish has been observed to increase after treatment with immunostimulants (Anderson 1992, Sakai 1999), vaccines (Bakopoulos et al 2003) and probiotics (Brunt et al 2007). In the present study, after goldfish were challenged with Aeromonas hydrophila, mortality declined in all treated groups.…”

“…However, treatment with antibiotics and chemicals failed to enhance lysozyme activity in the present study. An increase in the lysozyme concentration in fish blood can be caused by infections or invasion by foreign material (Fletcher & White 1973, Siwicki & Studnicka 1987.The survival rate of infected fish has been observed to increase after treatment with immunostimulants (Anderson 1992, Sakai 1999), vaccines (Bakopoulos et al 2003) and probiotics (Brunt et al 2007). In the present study, after goldfish were challenged with Aeromonas hydrophila, mortality declined in all treated groups.…”

Prevention of fish photobacteriosis. Comparison of the efficacy of intraperitoneally administered commercial and experimental vaccines

“…For the preparation of the experimental vaccine, the Phdp isolate was grown in the liquid media described by Bakopoulos et al (2003) for 48h at 21 ± 0.5 o C. All chemicals were supplied by Sigma Chemical Company, St Louis, MD, USA, unless otherwise stated.…”

“…The experimental vaccine was prepared as described by Bakopoulos et al (2003) but modified so that the culture liquid was not separated from bacterial cells. The bacterial cells concentration in the vaccine mixture was 10 9 bacterial cells/ mL.…”

“…A sample was then taken for the measurement of protein and carbohydrate content in the supernatants. Part of the bacterial mixture was then formalin-inactivated as described by Bakopoulos et al (2003) and this experimental vaccine mixture is referred to as EVF, hereafter. The other part of the bacterial mixture was heat inactivated at 57 o C for 30min.…”