Global intensification of tilapia production has raised questions on its susceptibility to a number of bacterial diseases.
Francisellosis is one of the most devastating tilapia infections and has a troubling impact on the tilapia production worldwide.
Francisella species can affect a diverse spectrum of animals including mammals, aquatic animals and invertebrates. Infections in tilapia are caused by Francisella noatunensis subsp. orientalis and are prevalent in tropic areas. The disease has a high percentage of mortality (50-90%) and is characterised by granulomas in multiple organs.
Acquired protection from diseases rely on vaccination. The market segment for tilapia vaccines is relatively novel and as a result of this only a limited number of vaccines for tilapia is available today.
Researchers at NMBU’s Department of Food Safety and Infection Biology (Matinf) have recently developed a new cohabitation model for vaccine trials in tilapia, and conducted a unique experiment which have never been conducted in Norway before.
«We have constructed small recirculation aquaculture system (RAS) for vaccine trials in Tilapia. The experiment was successfully completed and provided initial data on the effect of a new vaccine recently developed by the research groups of Professor Henning Sørum (NMBU) and Associate professor Hanne Winther-Larsen (UIO), said Dr. Alexander Kashulin, the researcher primarily involved in the development of the new model which was used for evaluation of the protective properties of the tilapia vaccine against Francisellosis.
The infrastructure of the established research facilities in Norway are mainly oriented towards cold-water marine and freshwater fish species, and as a result the researchers had to design a special installation for this experiment.
The cohabitation model developed by the research group resembled natural routes of disease transmittance and was designed in compliance with the existing European guidelines for evaluation of the efficacy of veterinary vaccines.
«The development of our new model is an excellent example of cooperation between different departments at NMBU and our campus partners. The fish for our studies were produced according to our specifications by the recently opened, state of the art Fish laboratory at the Department of Animal and Aquaculture Sciences (IHA). The department engineer Bjørn Reidar Hansen consulted us on the peculiarities of the tilapia behaviour and provided useful insights into maintenance of the tilapia in the RAS (recirculation aquaculture system) systems,» said Kashulin, and continued:
«The tropical setup was engineered and assembled by our group according to the biological requirements of tilapia and integrated into the existing infrastructure of the fish infection facility of the Norwegian Veterinary Institute (VI). With the support of Even Thoen, Head of the infection facility of VI, we were able to conduct a tilapia vaccination trial at NMBU’s campus in Oslo, which is home to NMBU School of Veterinary Medicine.»
Traditionally tilapia vaccines are tested in Asia. The distant location of the test grounds from Norwegian research facilities bring up additional costs for the vaccine inventors.
In addition to Asian research facilities, the tilapia vaccine trials can be performed in several European or American fish health laboratories on special request, but due to the fact that they can only be conducted on special request the associated expenses tend to be staggering.
«The new experimental model for testing tilapia vaccines was developed by the research group of Professor Henning Sørum at Matinf on special request by our project partners at the University of Oslo (UIO). Our laboratory provided expertise, state of the art facilities and conducted vaccine trials in tilapia, cod and salmon. As far as we know, vaccine trials on tilapia have never been conducted in Norway before. The newly developed model for vaccine trials has allowed us to provide our project partners with a competitive solution for testing vaccines and to substantially reduce the cost of the vaccine trial,» Kashulin concluded.