Microalgae as a Vaccine Delivery System to Aquatic Organisms

Aquaculture is one of the fastest growing food producing sector, as global aquaculture produces about 65 million metric tons of seafood valued at more than US$78 billion annually and supplies 50% of all the fish consumed in the world (Turchini et al., Fish oil replacement and alternative lipid sources in aquaculture feeds, CRC Press, Boca Raton, FL, 2010). On top of that, the aquaculture industry displayed an annual percentage of growth rate (APR) of 9.4% compared to other food producing sectors such as pigs farming (3.1%), poultry (5.1%), beef (1.2%), and mutton and lamb (1.0%). The aquaculture sector, especially fish, contributed up to 17% of animal proteins consumed worldwide and can reach up to 50% in some countries. In 2002, it was reported that the total world aquaculture production was worth 60 billion USD by value. One of the major and primary constraints in the aquaculture system production is disease outbreaks. They could be caused by bacteria, viruses, parasites and fungi. In the catfish industry, a loss of up to 60–80 million USD was caused by pathogenic bacteria Edwardsiella ictaluri and Flavobacterium culumnare. Apart from that, it was reported that a 50–100 million Euro annual loss in the salmon industry is caused by parasitic lice. Many strategies have been attempted to gauge and control this situation, but there is still an urgent need for better alternatives and also to explore the potential use of genetically modified organisms instead of antibiotics and chemical control. In this chapter, we focus on the potential and application of transgenic microalgae on aquaculture, as it has been dubbed as the organism of the future in terms of its utility, flexibility and, most importantly, sustainability.