Bacterial challenge induces variation of the Allograft Inflammatory Factor I (AIF-1) gene expression in Paracentrotus lividus.

The interest for echinoderm immune defence system is steadily increasing due to their phylogenetic, ecological, biotechnological and economical relevance. Their basal position within the deuterostome lineage makes the analysis of their defense mechanisms highly relevant to understand the evolution of the deuterostome immune system. Suggestions derive from the analysis of the immune genes and of their products, such as cytokines. The Allograft Inflammatory Factor-1 (AIF1), a calcium-binding cytokine and a key regulator of the immune response, play an important role during inflammation in Vertebrata. Recent literature evidences that proteins of the AIF1 superfamily are present in several phylogenetically distant species, all showing high similarity at the primary protein sequence level. In the present work, we report on the immune response of the sea urchin Paracentrotus lividus after a G+ bacteria challenge. The constitutive expression of AIF-1-like protein has been evidenced in P. lividus coelomocytes where the mRNA levels were found to be up-regulated at 24 h post-bacterial injection.