Biotechnology applied for controlling diseases in aquaculture in Norway and India

I dette prosjektet har vi undersøkt effekt av bakteriociner på fiskepatogener bakterier som gir sykdom hos oppdrettsfisk i Norge og under tempererte strøk, som India. I tillegg har vi studert bruk av vaksiner for forebyggelse av en alvorlig virusinfeksjon hos tilapia. Intracellulære agens som smitter fisk har en intracellulær infeksjonsrute og sprer seg eller bruker det intracellulære rommet til å gjemme seg bort fra immunresponsen til verten. Vi har studert muligheten for inkorporering av bacteriociner i nanoartikler og har vist at disse kan "bygges inn" i partiklene og størrelsesdistribusjonen er studert. Som et forebyggende tiltak har vi studert vaksinasjon mot Tilapia-lake virus infeksjon hos nil-tilapia og vist at det er mulig å utvikle vaksiner som beskytter mot alvorlig sykdom og død, spesielt basert på levende vaksiner (80% beskyttelse). Vaksinasjon basert på nye leveringsmåter, via urogenitalt organ hos tilapia, har også vært studert uten at det har gitt god beskyttelse. Formulerte, inaktiverte vaksiner gir også god beskyttelse mot død (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.