title: Molecular characterization, functional analysis, and defense mechanisms of two CC chemokines in Nile tilapia (Oreochromis niloticus) in response to severely pathogenic bacteria.
abstract: Two full-length cDNAs encoding CC chemokine genes in Nile tilapia (Oreochromis niloticus) (On-CC1 and On-CC2) were cloned and characterized. On-CC1 and On-CC2 showed signature cysteine motifs consisting of four cysteines. The expression levels of On-CC1 and On-CC2 were analyzed by RT-PCR, which showed that low expression of these two genes was only observed in the peripheral blood leukocytes (PBLs) and spleen of normal fish. Expression levels of these two molecules were quantified in 13 tissues of fish infected with virulent strains of Streptococcus agalactiae and Flavobacterium columnare. Most tissues, especially PBLs, the spleen and the liver, expressed significantly higher mRNA levels than the controls, particularly at 12 and 24 h after infection (P < 0.05). The current study strongly indicates that CC chemokine genes in Nile tilapia are crucially involved in the early immune responses to pathogens. Functional analyses clearly demonstrated that 10 and 100 μg/ml of recombinant rOn-CC1 and rOn-CC2 proteins efficiently enhanced the phagocytic activity (in vitro) of Nile tilapia phagocytes. Finally, Southern blot analysis and searching in Ensembl databases demonstrated that two different functional CC chemokine genes and other pseudogene fragments were discovered in the Nile tilapia genome.
authors: Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
authors: Chatsirin
authors: C
authors: Nakharuthai
authors: Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
authors: Nontawith
authors: N
authors: Areechon
authors: Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand. Electronic address: ffispssp@ku.ac.th.
authors: Prapansak
authors: P
authors: Srisapoome
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019742:Chemokines, CC / Q000235:genetics* / Q000378:metabolism; D023681:Cichlids / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D003001:Cloning, Molecular; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D045826:Flavobacteriaceae Infections / Q000276:immunology* / Q000382:microbiology; D005417:Flavobacterium / Q000276:immunology* / Q000472:pathogenicity; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D010587:Phagocytosis / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D013290:Streptococcal Infections / Q000276:immunology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D019742:Chemokines, CC; D029941:Fish Proteins; D012333:RNA, Messenger
keywords: CC chemokines; Chemotactic activity; Immune response; Nile tilapia; Phagocytosis