Sammendrag
Vibrio anguillarum is the causative agent of vibriosis, which is a serious disease problem in several marine fish species. Vaccination trials in Atlantic cod showed that significant protective immunity could be achieved against this disease though it was difficult to relate it to either specific antibody responses or natural antibodies. Probably other components of the Atlantic cod immune system are responsible for the observed protective immunity. Semi-quantitative RT-PCR analyses of selected immune- and metabolism-related genes were performed on the cDNAs of blood and spleen of Atlantic cod at 1, 3, 7 and 10 days post-vaccination (dpv) with heat-inactivated V. anguillarum. In the blood, there was an upregulation in the expression of certain antibacterial genes, reaching maximum levels by 7 dpv. Apolipoprotein A-I and the non-specific cytotoxic cell receptor protein (NCCRP-1) exhibited maximum expression at 3 and 7 dpv, respectively. The pro-inflammatory cytokines were also found to be significantly higher in the vaccinated fish. In the spleen, the transcript levels of genes involved in bacterial defense were elevated throughout the duration of sampling. The expressions of interferon stimulated gene-15 and interferon regulatory factor-1 were enhanced after vaccination. Likewise, the transcript levels of the NCCRP-1 and granzyme A/K were also upregulated. Among the antioxidant genes, the transcript levels of catalase and phospholipid hydroperoxide glutathione peroxidase (GSH-Px) significantly increased following vaccination. From among the glucose transport genes examined, only glucose transporter-4 (GLUT-4) was enhanced. These results show that Atlantic cod mounts a potent immune response following intraperitoneal vaccination with V. anguillarum antigen. These genes are involved in the acute phase response and could serve as valuable biomarkers of immune competence in Atlantic cod against vibriosis.
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