IL6 and infection: NNV, however, triggered in the gilthead seabream testis a slight down-regulation of tcrb and igmh genes upon in vivo infection and of il6 and il1b genes upon in vitro infection, whilst in the testis of European sea bass we observed up-regulations of the pro-inflammatory cytokine and igmh gene expressions upon in vivo infection and no changes upon in vitro infection.