Overexpression of T-bet, GATA-3 and TGF-ß Induces IFN-γ, IL-4/13A, and IL-17A Expression in Atlantic Salmon.

The overexpression of , and may theoretically induce , and expression, respectively. Whether this also applies to fish is not yet known. The plasmid vectors encoding reporter gene (RFP)-tagged , and were used as overexpression tools, transfected into cells or injected intramuscularly to monitor the expression of , and . In addition, the fish were either experimentally challenged with (VA group) or (PS group). The reporter gene (RFP) inserted upstream of the , and genes, was observed in muscle cell nuclei and in inflammatory cells after intramuscular (i.m.) injection. PS group: following the injection of and -encoding plasmids, the expression of and was high at the injection site. The spleen expression of , following the injection of a T-bet-encoding plasmid, was significantly higher on day 2. VA group: The and -overexpressing fish expressed high and mRNA levels in the muscles and on day 4 post-challenge. The expression of in the muscles of fish injected with -encoding plasmids was significantly higher on days 7 (8 days pre-challenge) and 19 (4 days after challenge). The protective effects of the overexpression of , and on both bacterial infections were negligible.