Ontogeny of Nile tilapia (Oreochromis niloticus) Immunoglobulin Type M Antibody Response

Nile tilapia (Oreochromis niloticus, Cichlidae) are cultured worldwide, however, the study of humoral immunity in these fish has been neglected, leading to mismanagement of prevention of common diseases by vaccination. In this study we purified and characterized the Nile tilapia immunoglobulin type M (IgM). In addition, we have described the production of a mouse polyclonal antibody for the investigation of the onset of antibody responses. After one-step purification using protein G sepharose beads, SDSPAGE, and mass fingerprint analysis we found that the heavy chain of Nile tilapia IgM was 70 kDa, whereas the light chain was 27 kDa. Western immunoblotting techniques using mouse anti-Nile tilapia IgM antibody, produced by intraperitoneal injection with purified Nile tilapia IgM for 3, periods with booster inoculations every 10 days, could effectively detect the onset of antibody responses in Nile tilapia sera at 42 days post-hatch