Development of fish vaccine in Southeast Asia: A challenge for the sustainability of SE Asia aquaculture.

Southeast (SE) Asia plays an important role in global food security as this region has been regarded as one of the major producers of aquaculture product and, to date, freshwater fish accounted for one-third of the total aquaculture in SE Asia. The intensification of freshwater farming corresponding to increase of consumer demands has inevitably led to the emergence and re-emergence of diseases causing tremendous economic loss in the region. Nile tilapia (Oreochromis niloticus) and striped catfish (Pangasianodon hypophthalmus), the major freshwater fish species of SE Asia, have been reported susceptible to several bacterial pathogens, e.g. Streptococcus agalactiae, Edwardsiella ictalurid and Flavobacterium columnare. Since only a limited number of vaccines being registered and marketed, these pathogenic organisms still represent a severe threat to aquaculture industry in SE Asia. However, there is profound advancement in the understanding of disease epidemiology, pathogenic mechanisms, teleost mucosal immunity and vaccine delivery system over the last few years. This review aimed to summarize those recent findings which hopefully can provide novel insight into the future development of suitable vaccine and vaccination regime against bacterial infection in SE Asia region.