MODULATION OF BARRIER FUNCTION AND INNATE IMMUNITY BY BACTERIAL INFECTION AND PAMP STIMULATION

Aquaculture has grown steadily in the last few decades playing an increasing role in meeting the demand for fish of a growing world population. One of the biggest challenges in aquaculture are disease caused by viruses, bacteria or fungi. The gills are the most susceptible organ in teleost fish exposed to various pathogens, parasites and pollutants. Thus, a healthy gill is essential to fight against any environmental insult. To investigate the barrier function of trout gill epithelia against bacterial infection, the cell monolayer was infected with Aeromonas salmonicida subsp. salmonicida, a pathogen of rainbow trout where the cell monolayer was found to allow a low percentage of bacterial cells to invade until one hour of infection which then increased at 3 and 6h of infection. Viral and bacterial PAMPs were found to upregulate the cellular integrity and reduce the percentage of bacterial cells to invade the monolayer to a significant level (Figure 1). Expression of innate immune genes were found to be upregulated upon bacterial infection and PAMP stimulation. Moreover, expression of a couple of antimicrobial peptides (AMPs) were also investigated where the expression was not induced significantly. The findings of the present study suggest a defense response to an infectious stimulus by modulating barrier function and by activating innate immunity. Overall, the findings of this study could facilitate developing antimicrobial drugs or vaccine conducive to the aquaculture production.