Vibriosis and furunculosis vaccines for Atlantic cod: efficacy, protective antigens and specific immune responses

Atlantic cod (Gadus morhua) is an upcoming marine species in Norwegian fish farming industry. Bacterial diseases as vibriosis and furunculosis, are causing problems and efficient vaccines will be crucial in order to develop a sustainable industry. Today, most cod juveniles are vaccinated against vibriosis, but the disease is still a problem, while atypical furunculosis vaccines are not available. The heterogeneity of both V. anguillarum and A. salmonicida is a challenge in development of efficient vaccin es that aim to protect against all variants of the bacteria. In order to investigate the variability among A. salmonicida and V. anguillarum, isolates will be collected from outbreaks along the Norwegian coast. Isolates will be phenotypically verified bef ore subjected to genetic characterisation. Vaccine efficacy and cross protection of mono- and multivalent vibriosis and furunculosis vaccines will be investigated when challenged with various variants of the isolates. Vaccine efficacy will also be compar ed in families of subpopulations of Atlantic cod; Arctic and coastal cod from the national cod breeding program. Knowledge about similarity/variability in surface epitopes recognised by the cod immune system is important for vaccine development. Thus, vac cine candidates such as surface components like A-layer protein and LPS ,will be subjected to further characterisation and compared among genetically deviating isolates. Cod produce specific antibodies against certain antigens, but the responses against V . anguillarum are showed to be weak with significant individual variations. The nature of cod B cells and the function of the cod humoral immune system will be studied and will give valuable information to vaccine development. Furthermore, specific genes and pathways actually stimulated by a vaccine and possibly also responsible for the protection to V. anguillarum, will be identified by expression profiling.