When European sea bass and gilthead seabream specimens were infected with a strain of nodavirus (RGNNV), which is highly pathogenic for European sea bass where it mainly affects the brain and retina tissues, but not for gilthead seabream (a reservoir species) [69,70], prx1 was up-regulated in the head-kidney and brain after 1 day but down-regulated in the brain after 15 and 30 days after infection in the gilthead seabream. The gene discussed is PRDX1; the disease is infection.