The Immune System Of Bony Fish

Teleost fish have undergone several rounds of genome duplication in their evolutionary history. The duplication and deletion of their genes has had a profound effect on their immune system and responses. Teleosts have all of the familiar elements of the vertebrate immune system: B cells, T cells, recombining receptors, etc. However, in many cases the structure and regulation of these immune effectors differs from mammalian equivalents. For example, teleost IgM multimers are tetramers, not pentamers, and secondary responses are nonexistent. This is in part due to the altered genetic structure and divergent evolutionary path of teleosts, but differences seen here also reflect the fact that teleost fish are cold-blooded, and thus their environment has profound effects on their metabolism and immune response.