Recently, the proliferation of infectious diseases due to intensification of aquaculture has become an issue of serious conversation among scientists, where fish mortality due to pathogens result in losses of up to 80-100% in some cases. This has challenged research in vaccine development, since the use of anti-microbial chemicals result in resistant strains and lead to accumulation of toxic residues in products and their negative impact to the environment are all issues being avoided on the short and long term.

Meanwhile, developing vaccines for fish seem to pose serious challenges, due in part, to the fact that fish rely more on innate rather than acquired immunity. Since fish vaccines are highly specific to pathogens and act on short-term, this means multiple applications of multivalent vaccines which have additional costs, takes time and stress the fish.

Nonetheless, a new strategy is currently under development with relative success, where safe bacteria strains (LAB) are bio-engineered as vectors to deliver and express medical proteins (cytokines) in the mucosal immune system and protect fish from pathogens. The application of such new vaccines orally has additional advantages, in that it saves time and the cost of vaccination experienced by dipping and IP injection, not to mention eliminates stress suffered by fish.

Unfortunately based on EU and other guidelines, such organisms are categorized as GMO, thus limiting their potential use. Considering that the use of such organisms has been going on for ages in the food industry (Yoghurt, cheese, etc.) secretly or openly, please share your thoughts on why or why not this categorization is justifiable? Do the guidelines need to be reviewed, to cater for these emerging trends?