Akirins in sea lice: First steps towards a deeper understanding

•We obtained the my32-Cr cDNA ends by RACE-PCR.•We cloned the uncharacterized L. salmonis akirin-2 (my32-Ls) based on EST sequence.•These genes/proteins have the main characteristics of akirins from invertebrates.•3D models predicted a α-helical structure in the ‘non-disordered’ C-terminal region.•Immunization with purified my32-Ls elicited a specific antibody response in mice and fish. Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon industry. Vaccination could be an environmentally friendly alternative for sea lice control; however, research on the development of such vaccines is still at an early stage of development. Recent results have suggested that subolesin/akirin/my32 are good candidate antigens for the control of arthropod infestations, including sea lice, but background knowledge about these genes in crustaceans is limited. Herein, we characterize the my32 gene/protein from two important sea lice species, Caligus rogercresseyi and Lepeophtheirus salmonis, based on cDNA sequence isolation, phylogenetic relationships, three dimensional structure prediction and expression analysis. The results show that these genes/proteins have the main characteristics of akirins from invertebrates. In addition, immunization with purified recombinant my32 from L. salmonis elicited a specific antibody response in mice and fish. These results provide an improvement to our current knowledge about my32 proteins and their potential use as vaccine candidates against sea lice in fish.