title: Cloning and expression of a surface immunogenic protein in Streptococcus dysgalactiae isolated from fish and its application in enzyme-linked immunosorbent assays to diagnose S. dysgalactiae infections in fish.
abstract: Lancefield group C Streptococcus dysgalactiae (GCSD) causes severe necrotic lesions in the caudal peduncle in the genus Seriola farmed in Japan. To develop a sero-diagnostic method for GCSD infection in farmed fish, we attempted to identify a surface immunogenic protein that induces an antibody after infection with GCSD by immunoblot analysis using sera collected from infected fish. A protein obtained from sodium dodecyl sulfate (SDS) extracts of GCSD was identified as S. dysgalactiae surface immunogenic protein (Sd-Sip). Sd-Sip exhibited more than 94% homology with a surface antigen or a hypothetical protein from S. dysgalactiae mammalian isolates at the nucleotide sequence level. Expression of the recombinant Sd-Sip (rSd-Sip) was confirmed by immunoblot analysis, that is, its reactivity to GCSD-infected sera. Antibody detection ELISA using rSd-Sip and their usefulness for diagnosis of GCSD infection were examined. GCSD-infected sera collected from farmed amberjack, Seriola dumerili (Risso), showed strong reaction with immobilized rSd-Sip. Meanwhile, sera immunized by other pathogenic bacteria of fish were showed ELISA values similar to those of non-infected sera. These results of this study suggest that the antibody detection ELISA using rSd-Sip is an effective diagnostic method for GCSD infection in fish.
authors.affiliation: Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Miyazaki, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Nishiki
authors.forename: T
authors.initials: T
authors.lastname: Minami
authors.forename: T
authors.initials: T
authors.lastname: Itami
authors.forename: T
authors.initials: T
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D005393:Fish Diseases / Q000175:diagnosis* / Q000382:microbiology; D005398:Fisheries; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000235:genetics*
chemical_list: D000942:Antigens, Bacterial
keywords: Streptococcus dysgalactiae; diagnosis; enzyme-linked immunosorbent assay; surface immunogenic protein