TNF and infection: Interestingly, the expression of tumour necrosis factor alpha (tnfa) was previously suggested to be substantially higher in species susceptible to NNV, such as European sea bass, compared with its expression in species resistant to NNV, such as gilthead seabream, which could indicate that this proinflammatory cytokine may be responsible for a large inflammatory reaction in the areas of infection of this virus, such as the brain, retina and spinal cord, producing a neurodegenerative process that the fish cannot overcome (32).