Towards the development of nanobead vaccines against salmon pathogens: : establishment of cold-water fish infection models

Abstract

As the fish farming industry is growing all over the world, economic losses caused by diseases are also increasing. In Norway one fifth of the farmed fish are lost due to viral diseases; there is no treatment for viral infections and only a few of the vaccines available are effective. Therefore a new approach to vaccine formulation is urgently needed. The purpose of this project was to establish a nanobead-based vaccine for cold-water fish pathogens. The salmon viruses Infectious salmon anemia virus (ISAV), Infectious pancreatic necrosis virus (IPNV), Salmon pancreas disease virus (SPDV) and a bacterium Piscirickettsia salmonis were studied. First, methods to produce pure pathogen suspensions suitable for nanobead formulation were established. Then, to set the stage for nanobead formulation, some of the viruses were fluorescently labeled, and the surface charges were measured. In order to set a foundation for the infection studies in vivo, cold-water Zebrafish and Medaka systems were established and the fish injection protocol was optimized. We proved the efficiency of the injection protocol by injecting adult Zebrafish and Medaka at 28 °C with Francisella orientalis which resulted in death of all the injected fish within one week. However, efforts to establish cold-water fish pathogen infection model in Zebrafish or Medaka in which the infected fish could be distinguished from uninfected fish were not successful. Nevertheless, we showed that both Zebrafish and Medaka can be used as a model system for cold-water fish and the methods already established allow us to screen for other cold-water fish pathogens which might be used for nanobead-based vaccination studies in Zebrafish and/or Medaka.