Molecular cloning and characterization of LPS-binding protein/bactericidal permeability-increasing protein (LBP/BPI) from olive flounder, Paralichthys olivaceus

A lipopolysaccharide (LPS)-binding protein/bactericidal permeability-increasing protein (LBP/BPI) homolog was isolated from peripheral blood leukocytes cDNA library of olive flounder Paralichthys olivaceus. The isolated LBP/BPI cDNA is 2806bp in length with a 1419bp open reading frame (ORF) that encodes a protein of 472 amino acid residues. The LPS-binding domain is well conserved in the N-terminal barrel, showing high sequence identities with other teleost LBP/BPI as well as those of mammals. RT-PCR analysis revealed that mRNA expression of LBP/BPI was significantly elevated in all tested tissues (liver, gill, intestine, head kidney, and spleen) after intraperitoneal injection of the gram-negative bacterium Edwardsiella tarda or the gram-positive bacterium Streptococcus iniae. This expression pattern profile corresponded to that of acute inflammatory cytokines, suggesting that it plays a role in the innate immune response, in particular, the acute phase response.