Biotechnology applied for controlling diseases in aquaculture in Norway and India

In this project, we have investigated the effect of bacteriocins on fish pathogenic bacteria that cause disease in farmed fish in Norway and under temperate regions, such as India. In addition, we have studied the use of vaccines to prevent a serious viral infection in tilapia. Intracellular agents that infect fish have a route of infection with spread through the intracellular space to hide away from the host's immune response. We have studied the possibility of incorporating bacteriocins in nanoarticles and have shown that these molecules can be "built into" the particles and the size distribution has been studied. As a preventive measure, we have studied vaccination against Tilapia-lake virus infection in Nile-tilapia and shown that it is possible to develop vaccines that protect against serious illness and death, especially based on live vaccines (80% protection). Vaccination based on new delivery methods, via the urogenital organ in tilapia, has also been studied without giving good protection. Formulated, inactivated vaccines also provide good protection against death (77%).

Better understanding of characteristics of key pathogenic bacteria infecting warm water farmed fish species, like Aermonads and Edwardsiella sp. Characterised antimicrobial activity of garvicin C towards a number of fish pathogenic bacteria, infecting warm-water and cold-water fish species. Early host-pathogen interactions for Tilapia lake virus infection in nile tilapia showing that the virus downplays innate immune responses at early time likely paving the way for successful virus replication.

The potentials in modern biotechnology have not been unleashed in the field of aquaculture. Particularly taking advantage of new knowledge translated into new approaches for treatment and infection control, including use of inhibitory gut probiotics based on local (gut) production of bacteriocins. New and better understanding of protective antigens of bacterial species opens up cross-genera protective vaccines. We know that vaccines for fish have to be formulated for targeted delivery and for prolonged retention and immune stimulation. Here we see unleased potential for a combination of biotechnological solutions and modern nanotechnology for next generation antigen production and delivery (nanomedicine). We will use biotechnology as a platform for new approaches and new solutions of disease control and prevention. Our efforts will include testing out bacteriocin produced by probiotic bacteria for novel treatment of bacterial diseases targeted delivery of bacteriocins to infected fish. Use of antibiotics is not the preferred option but sometimes needed to control acute disease incidents. One challenge is that antibiotics are delivered orally which can result in unwanted impact on gut microbiota of the fish, poor bioavailability and release to environment plus that many pathogens reside in cells or cellular compartments not accessible to antibiotics. We will use modern nanotechnology for intracellular delivery of antibiotics using E. tarda infection as a model. Further we will develop vaccines based on genus-specific antigens from bacteria like Aeromonas hydrophila and Edwardsiella tarda infecting rohu and tilapia, the potential is to provide protection across bacterial genera. New vaccines for infections for which there are currently no preventive measures, i.e. yersiniosis in sea water of salmon and tilapia lake virus of tilapines will be developed and tested by in vivo vaccination and challenge experiments.