How can plant genetic engineering contribute to cost-effective fish vaccine development for promoting sustainable aquaculture?

Jihong Liu Clarke 0 1 2 3 Mohammad Tahir Waheed 0 1 2 3 Andreas G. Lossl 0 1 2 3 Inger Martinussen 0 1 2 3 Henry Daniell 0 1 2 3 0 A. G. Lossl Department of Crop Sciences, University of Natural Resources and Applied Life Sciences , Vienna, Austria 1 M. T. Waheed Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University , Islamabad 45320, Pakistan 2 J. L. Clarke (&) I. Martinussen Bioforsk, Norwegian Institute for Agricultural and Environmental Research , A s, Norway 3 H. Daniell Departments of Biochemistry and Pathology, University of Pennsylvania School of Dental Medicine , 240 South 40th St, 547 Levy Building, Philadelphia, PA 19104, USA Aquaculture, the fastest growing food-producing sector, now accounts for nearly 50 % of the world's food fish (FAO in The state of world fisheries and aquaculture. FAO, Rome, 2010). The global aquaculture production of food fish reached 62.7 million tonnes in 2011 and is continuously increasing with an estimated production of food fish of 66.5 million tonnes in 2012 (a 9.4 % increase in 1 year, FAO, www.fao.org/fishery/topic/16140). Aquaculture is not only important for sustainable proteinbased food fish production but also for the aquaculture industry and economy worldwide. Disease prevention is the key issue to maintain a sustainable development of aquaculture. Widespread use of antibiotics in aquaculture has led to the development of antibiotic-resistant bacteria and the accumulation of antibiotics in the environment, resulting in water and soil pollution. Thus, vaccination is the most effective and environmentally-friendly approach to combat diseases in aquaculture to manage fish health. Furthermore, when compared to [760 vaccines against - human diseases, there are only about 30 fish vaccines commercially available, suggesting the urgent need for development and cost-effective production of fish vaccines for managing fish health, especially in the fast growing fish farming in Asia where profit is minimal and therefore given high priority. Plant genetic engineering has made significant contributions to production of biotech crops for food, feed, valuable recombinant proteins etc. in the past three decades. The use of plants for vaccine production offers several advantages such as low cost, safety and easy scaling up. To date a large number of plant-derived vaccines, antibodies and therapeutic proteins have been produced for human health, of which a few have been made commercially available. However, the development of animal vaccines in plants, especially fish vaccines by genetic engineering, has not yet been addressed. Therefore, there is a need to exploit plant biotechnology for cost effective fish vaccine development in plants, in particular, edible crops for oral fish vaccines. This review provides insight into (1) the current status of fish vaccine and vaccination in aquaculture, (2) plant biotechnology and edible crops for fish vaccines for oral administration, (3) regulatory constraints and (4) conclusions and future perspectives. Fish is an excellent animal protein source and contains a wide range of essential human nutrients. Up to 80 % of the worlds fish production is used for human consumption, indicating the important role of aquaculture for food security. Fisheries and aquaculture play also an important role in the livelihoods of millions of people worldwide from the small-scale inland fishermen who harvest fishes from lakes and rivers to the industrial scale fish farming. Thus, sustainable fish farming contributes considerably to food security (www.fao.org). Aquaculture is the farming of aquatic organisms including fish, crustaceans, molluscs and aquatic plants. Fisheries and aquaculture make important contributions to the human population as protein sources. The global aquaculture production of food fish reached 62.7 million tonnes in 2011 and is continuously increasing with an estimated production of food fish of 66.5 million tonnes in 2012 (a 9.4 % increase in 1 year, FAO, www.fao.org/ fishery/topic/16140). In the past five decades, the world fish supply has rapidly increased with an average growth rate of 3.2 % per year and constitutes an important source of nutrition and animal protein for humans (FAO 2012; http://www.fao.org, Fig. 1). This is particularly the case in Asia, where approximately 90 % of the total global aquaculture products comes from. Among the Asian countries, China alone produces ca. 70 % of the world total volume of aquaculture products and has become the largest producer of farmed seafood in the world, with an increase of 490 % since 1978 (Ellis 2009). It is estimated that in the next decade total production from both capture and aquaculture will exceed that of beef, pork or poultry. Due to higher demand for fish, world fisheries and aquaculture production are projected to reach about 172 million tonnes in 2021, of which aquaculture is projected to reach about 79 million tonnes, rising by 33 % over the period 20122021 (FAO 2012, http://www.fao.org). This boom in aquaculture will help to achieve certain millennium development goals either directly (e.g. eradication of extreme poverty and hunger) or indirectly (e.g. substantial improvement in economies). However, aquaculture is as vulnerable to adverse impacts of disease and unfavourable environmental conditions as is farming of other animals. Disease outbreaks in recent years have affected Atlantic salmon, oyster and marine shrimp farming in several countries of the world, resulting in partial or sometimes total loss of production. In 2010, aquaculture in China suffered production losses of 1.7 million tonnes caused by natural disasters, diseases and pollution. Disease outbreaks virtually wiped out marine shrimp farming production in Mozambique in 2011 (FAO 2012). Fish diseases not only pose a threat to the aquaculture industry but also to human livelihood and health. Apart from zoonoses, use of certain chemicals and antibiotics for fish health also pose certain risks to the environment, human health and food security (for a review see Sapkota et al. 2008). Management of aquatic animal health is therefore an important issue for food security, to protect livelihoods of millions of people, the aquaculture industry and the environment. Fig. 1 Worldwide fish production in five decades. Data source (www.fao.org/fishery/aquaculture) History and current status of fish vaccines and vaccination approaches Compared with human vaccine history starting from the discovery of vaccination by Edward Jenner in 1796 leading to production of [760 vaccines for protecting human health, fish vaccine development has a very short history with roughly 40 years since the 1970s. It took over three decades from the first scientific report describing fish vaccination using an inactivated orally administrated Aeromonas salmonicida vaccine. The first licensed fish vaccine was made commercially available in 1976 (Evelyn 1997). The first fi (...truncated)