Bath vaccination of rainbow trout (Oncorhynchus mykissWalbaum) againstYersinia ruckeri: Effects of temperature on protection and gene expression

• Published in: Vaccine 2008-02, Vol.26 (8), p.1050
• Main Authors: Raida, MK, Buchmann, K
• Format: Article
• Language: English
• Subjects: Drinking water; Fish; Gene expression; Immunization; Infections; Salmon; T cell receptors; Trout; Vaccines; Water temperature
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2007.12.029

Protection of rainbow trout fry following bath vaccination with a bacterin ofY. ruckeriO1, the bacterial pathogen causing enteric red mouth disease (ERM), was investigated at 5, 15 and 25°C. Rainbow trout fry were acclimatised for 8 weeks at the three temperatures before vaccination. They were subsequently challenged withY. ruckeri4 and 8 weeks post-vaccination which demonstrated a significant protection of vaccinated fish kept at 15°C. No protective effect of vaccination in rainbow trout reared at 5 and 25°C could be recorded. Spleen tissue was sampled from vaccinated and control fish at 0, 8, 24 and 72h post-vaccination in order to analyse gene transcript profiles using quantitative real-time RT-PCR (q-PCR). Gene expression in fish vaccinated at 15°C (the protected fish) was up-regulated with regard to the pro-inflammatory cytokines IFN-γ, TNF-α, IL-6 and the anti-inflammatory cytokines IL-10 and TGF-β, the cell receptors TcR, CD8α, CD4, C5aR and the teleost specific immunoglobulin IgT. Passive immunisation using transfer of plasma from vaccinated fish to naïve fish conferred no protection. This indicates that humoral factors such as Ig and complement are less important in the protection induced by bath vaccination. Expression of cellular factors such as CD8α was significantly increased in the protected trout and this suggests that cellular factors including cytotoxic T-cells could play a role in immunity againstY. ruckeri.