Identification, Characterization, and Expression Analysis of CD79A and CD79B in the Sichuan Taimen (Hucho bleekeri)

In the immune system, humoral immunity is mediated by B lymphocytes that destroy antigens through the production of antibodies by plasma cells. The CD79A and CD79B play important roles in the transduction of antigen-stimulated signals. However, only a few studies have investigated the immune functions of CD79A and CD79B in teleosts. To understand the role of CD79 in teleosts, CD79A and CD79B were identified and functionally analyzed in a glacial relict Hucho bleekeri. CD79A and CD79B contain a typical signal peptide, an immunoglobulin domain, a transmembrane region, and a cytoplasmic tail. The amino acid sequence of H. bleekeri CD79 showed high homology with CD79 of salmonid fish. Phylogenetic analysis also showed that H. bleekeri CD79A and CD79B clustered with the CD79 of Salmonidae fish, including the genera Salmo, Oncorhynchus, and Salvelinus. Tissue expression analysis showed that CD79A and CD79B were widely expressed in all the tested tissues. The highest expression of CD79A and CD79B was found in the head kidney, spleen, and trunk kidney, whereas the lowest expression was observed in the stomach, skin, gonad, and muscles. After lipopolysaccharides and polyinosinic:polycytidylic acid stimulation, the expression levels of CD79A and CD79B in the head kidney and spleen of H. bleekeri changed significantly. Our study showed that CD79 may play a crucial role in the B-cell receptor signaling pathway and immune response in H. bleekeri.