A teleost complement factor Ba possesses antimicrobial activity and inhibits bacterial infection in fish. (June 2017)

• Record Type: Journal Article
• Authors: Li, Xue-peng; Sun, Li
• Is Part Of: Developmental and comparative immunology. Volume 71(2017)
• Page Start: 49
• Page End: 58
• Publication Date: 2017-06
• Subjects: Complement factor B -- Cynoglossus semilaevis -- Antimicrobial -- Bacterial infection; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2017.01.021
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Complement factor B (Bf) is a component of the complement system. Following activation of the alternative pathway of the complement system, factor B is cleaved into Ba and Bb fragments. In fish, the Bf of rainbow trout is known to act as a C3 convertase, but the function of the Ba fragment is essentially unknown. In this study, we examined the expression patterns of tongue sole Cynoglossus semilaevis Bf (named CsBf) and the biological activity of the Ba fragment of CsBf (named CsBa). CsBf possesses the conserved domains of Bf and shares 39.9%–56.4% sequence identities with other fish Bf. CsBf expression was high in liver, muscle, and heart, and low in intestine, blood, and kidney. Bacterial infection significantly induced CsBf expression in kidney, spleen, and liver in a time-dependent manner. Recombinant CsBa (rCsBa) exhibited apparent binding capacities to bacteria and tongue sole peripheral blood leukocytes, and binding of rCsBa to bacteria inhibited bacterial growth. When overexpressed in tongue sole, CsBa significantly reduced bacterial dissemination in fish tissues. Together these results indicate for the first time that a fish Ba possesses antibacterial effect as well as immune cell-binding capacity, and thus probably plays a role in host immune defense against bacterial infection. Highlights: The complement factor B of tongue sole (CsBf) has conserved domains of factor B. CsBf expression was found in multi-tissues and upregulated by bacterial infection. Recombinant CsBfa (rCsBfa) bound to bacteria and peripheral blood leukocytes. Binding of rCsBfa to bacterial inhibited bacterial growth. Overexpression of CsBfa in tongue sole inhibited bacterial dissemination in tissues.