title: Effects of phosphoglucomutase gene (PGM) in Streptococcus parauberis on innate immune response and pathogenicity of olive flounder (Paralichthys olivaceus).
abstract: In recent years, Streptococcus parauberis infection has been an emerging problem in aquaculture in South Korea because of its more frequent isolation than other streptococcal bacteria including Streptococcus iniae. To develop effective treatment and prophylaxis methods against this emerging disease by S. parauberis, it is necessary to understand the underlying pathogenic mechanisms. To uncover the pathogenicity, the mutant strain of S. parauberis with a deleted phosphoglucomutase (PGM) gene which has been known to be an important virulence factor in bacterial pathogens was generated to investigate the relationship between virulence and gene function using an allelic exchange mutagenesis method. Allelic exchange mutagenesis of the phosphoglucomutase gene resulted in phenotype changes including decreased extracellular capsules, reduced buoyancy, increased hydrophobicity and reduced growth. Moreover, the S. parauberis mutant was more sensitive to innate immune clearance mechanisms including serum, mucus and phagocyte killing and could not induce mortality in olive flounder. These phenotype changes and the attenuated virulence of the pathogen to fish could be due to the reduction in capsule production by mutation of the PGM gene. The results provide evidences that phosphoglucomutase expression contributes to S. parauberis virulence in fish by affecting bacterial survival against the host's humoral and cellular defense mechanisms.
authors.affiliation: Institute of Fisheries Sciences, Pukyong National University, 474, Ilgwang-Ro, Ilgwang-myeon, Gijang-gun, Busan 619-911, South Korea; Department of Aquatic Life Medicine, Pukyong National University, 45, Yongso-ro, Namgu, Busan 608-737, South Korea. Electronic address: ily337@daum.net.
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Woo
authors.affiliation: Department of Aquatic Life Medicine, Pukyong National University, 45, Yongso-ro, Namgu, Busan 608-737, South Korea. Electronic address: parksi@pknu.ac.kr.
authors.forename: Soo Il
authors.initials: SI
authors.lastname: Park
mesh_terms: D000818:Animals; D017756:Aquaculture; D003001:Cloning, Molecular; D021821:Communicable Diseases, Emerging / Q000276:immunology / Q000662:veterinary*; D017931:DNA Primers / Q000235:genetics; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology*; D005432:Flounder; D055786:Gene Knockout Techniques; D007113:Immunity, Innate / Q000276:immunology; D046529:Microscopy, Electron, Transmission; D016296:Mutagenesis; D010733:Phosphoglucomutase / Q000235:genetics* / Q000276:immunology; D016133:Polymerase Chain Reaction; D056910:Republic of Korea; D013290:Streptococcal Infections / Q000276:immunology / Q000662:veterinary*; D013291:Streptococcus / Q000201:enzymology* / Q000472:pathogenicity
chemical_list: D017931:DNA Primers; D010733:Phosphoglucomutase
keywords: Allelic exchange mutagenesis; Olive flounder Paralichthys olivaceus; Phosphoglucomutase; Streptococcus parauberis; Virulence factor