title: Expression of the serum opacity factor gene and the variation in its upstream region in Streptococcus dysgalactiae isolates from fish.
abstract: Group C Streptococcus dysgalactiae (GCSD) is a pathogen of farmed fish. Almost all GCSD isolates from Asian countries, including Japan, Taiwan, Malaysia, and China, have a serum opacity factor (SOF-FD). Although the SOF-FD sequences in different GCSD isolates are identical, different opacification activities are observed. Three types of variations were observed in the upstream sequence of the sof-FD gene in GCSD isolates with different SOF-FD activities. Type 1 was characterized by insertion of an IS981-like element into the upstream region of the sof-FD gene. In Type 2, an IS981-like element was inserted into the upstream region in a direction opposite to that in Type 1. In Type 3, no IS element was inserted. Type 1 was predominant among Japanese isolates (129 of 133). Isolates from other Asian countries were generally Type 3 (13 of 16). Except for 1 strain, Type 1 strains exhibited opacification activities with optical densities (ODs)>0.6, while Type 2 and Type 3 strains have low opacification activities (ODs >0.2). Only Type 1 strains have putative -10 and -35 promoter regions upstream of the sof-FD gene, and the expression level of the sof-FD gene was higher in Type 1 strains than in Type 2 and Type 3 strains.
authors: Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, Miyazaki, Miyazaki 889-2192, Japan.
authors: Issei
authors: I
authors: Nishiki
authors: Takayuki
authors: T
authors: Minami
authors: Shih-Chu
authors: SC
authors: Chen
authors: Toshiaki
authors: T
authors: Itami
authors: Terutoyo
authors: T
authors: Yoshida
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002681:China; D004251:DNA Transposable Elements; D005393:Fish Diseases / Q000382:microbiology*; D005838:Genotype; D007564:Japan; D008296:Malaysia; D016254:Mutagenesis, Insertional; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010473:Perciformes / Q000382:microbiology*; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D017422:Sequence Analysis, DNA; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013624:Taiwan
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; C021908:opacity factor; D010447:Peptide Hydrolases