title: CsSAP, a teleost serum amyloid P component, interacts with bacteria, promotes phagocytosis, and enhances host resistance against bacterial and viral infection.
abstract: Serum amyloid P component (SAP) is a member of the pentraxins family that plays important roles in innate immunity in vertebrates. In fish, the biological function of SAP is essentially unknown. In this study, we examined the expression and function of a SAP homologue (CsSAP) from tongue sole Cynoglossus semilaevis. CsSAP shares 46%-58% overall sequence identities with known fish SAP and was upregulated in expression by bacterial and viral infection. Recombinant CsSAP (rCsSAP) exhibited differential binding capacities to a wide range of Gram-positive and Gram-negative bacteria and promoted uptake of the bound bacteria by host phagocytes. When introduced in vivo, rCsSAP enhanced host resistance not only to bacterial infection but also to viral infection. Consistently, antibody blockage of CsSAP significantly weakened the ability of tongue sole to clear invading bacteria. These results provide the first evidence that fish SAP contributes significantly to both antibacterial and antiviral immunities.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China. Electronic address: lsun@qdio.ac.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019138:Antibodies, Blocking / Q000008:administration & dosage; D001424:Bacterial Infections / Q000276:immunology*; D058491:Bacterial Load / Q000187:drug effects; D005393:Fish Diseases / Q000276:immunology*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D005412:Flatfishes / Q000276:immunology*; D005786:Gene Expression Regulation; D054884:Host-Pathogen Interactions / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D010587:Phagocytosis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D000683:Serum Amyloid P-Component / Q000235:genetics / Q000378:metabolism*; D014777:Virus Diseases / Q000276:immunology*
chemical_list: D019138:Antibodies, Blocking; D029941:Fish Proteins; D000683:Serum Amyloid P-Component
keywords: Antibacterial; Antiviral; Cynoglossus semilaevis; Innate immunity; Serum amyloid P component