Serological Characterization of Streptococcus iniae Strains Isolated from Cultured Fish in Japan

Kanai, Kazuaki; Notohara, Masakazu; Kato, Tatsuo; Shutou, Kimihiro; Yoshikoshi, Kazuma

doi:10.3147/jsfp.41.57

Cited by 14 publications

(19 citation statements)

References 49 publications

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“…They were routinely cultured using Todd-Hewitt agar or broth (Difco Laboratories) for 18 -24 h at 27∞C. FKC of each strain was prepared as described previously (Kanai et al, 2006).…”

Section: Bacteriamentioning

confidence: 99%

“…Blood was collected from the residual five fish of each group and serum was separated from the blood by centrifugation at 900 ¥ g for 15 min. Agglutination titers of the sera were measured with FKC of S. iniae NUF631 and NUF44 (K -type) according to the previous paper (Kanai et al, 2006). Average water temperature during the vaccination period and after challenge was 25.5∞C and 26.3∞C, respectively.…”

Section: Vaccination Testmentioning

confidence: 99%

“…Transmission electron microscopy (TEM) of cell surface of S. iniae Preparation of samples for TEM was performed as described by Kanai et al (2006). S. iniae NUF631 and 6-20 cells were pretreated with an equal volume of normal or immune flounder sera.…”

Section: Phagocytic Activities Of Flounder Peritoneal Macrophagesmentioning

confidence: 99%

“…However, neither defense mechanisms of vaccinated fish nor protective antigens have not been clarified yet. Kanai et al (2006) reported the presence and properties of two serological phenotypes, designated K + type and K -type, in Japanese S. iniae isolates. They showed that strains of K + type possessed a type-specific antigen, cell surface acidic polysaccharides and a capsule, and that vaccination with formalin-killed cells (FKC) of K + type, but not with K -type FKC, confers high protective immunity on Japanese flounder against S. iniae infection.…”

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confidence: 99%

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Role of Capsule in Immunogenicity of Streptococcus iniae to Japanese Flounder Paralichthys olivaceus

2007

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ABSTRACT-Streptococcus iniae causes an acute systemic disease in Japanese flounderParalichthys olivaceus, one of the important cultured fish in Japan. Although commercial S. iniae vaccines have been developed and used in farms since 2005, the immunoprotection mechanism in vaccinated fish has not been elucidated yet. To verify the involvement of capsular polysaccharides of S. iniae in immunoprotection, we compared the protective efficacy of formalin-killed cells (FKC) of S. iniae NUF631 (capsulated) with those of its isogenic capsular-deleted mutants in S. iniae infection of Japanese flounder. As a result, high protection was achieved by immunization with NUF631 FKC but not with mutant FKC. Viable count of intravenously inoculated NUF631 decreased in the kidney of flounder immunized with NUF631 FKC, and NUF631 cells opsonized with anti-NUF631 flounder serum elevated the phagocytic activity and reactive oxygen species production of flounder peritoneal macrophages. In electron microscopic examination, electronically dense materials were observed on the capsule of NUF631 cells pretreated with the antiserum, and in western blot analysis flounder antibody was detected in the antiserum components bound to NUF631 cells. These findings indicate that capsular polysaccharides are important protective antigens and anti-capsule antibody plays a protective role as an opsonin in flounder S. iniae infection.

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“…They were routinely cultured using Todd-Hewitt agar or broth (Difco Laboratories) for 18 -24 h at 27∞C. FKC of each strain was prepared as described previously (Kanai et al, 2006).…”

Section: Bacteriamentioning

confidence: 99%

Section: Vaccination Testmentioning

confidence: 99%

Section: Phagocytic Activities Of Flounder Peritoneal Macrophagesmentioning

confidence: 99%

mentioning

confidence: 99%

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Role of Capsule in Immunogenicity of Streptococcus iniae to Japanese Flounder Paralichthys olivaceus

2007

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“…Kanai et al (2006) reported the presence and properties of two serological phenotypes, designated K + type and K -type, in Japanese S. iniae isolates, mainly from Japanese flounder. They showed that K + type exhibited a typespecific antigen and acidic polysaccharides in the autoclave-extracts of cells and a capsule on the cell surface, and that strains of K + type were virulent for Japanese flounder whereas those of K -type were avirulent.…”

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confidence: 99%

Virulence Attenuation of Capsular Polysaccharide-deleted Mutants of Streptococcus iniae in Japanese Flounder Paralichthys olivaceus

2007

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ABSTRACT-Streptococcus iniae is known as an important bacterial pathogen causing serious damage in fish culture industry worldwide. Although the capsule of this pathogen is suggested to play a role in the disease process, it has not been verified yet. In this study we created isogenic uncapsulated mutants of S. iniae NUF631 by Tn916 transposon mutagenesis and investigated the role of capsule in the virulence and resistance to phagocytic activities of peritoneal macrophages of Japanese flounder Paralichthys olivaceus. Mutants transformed from K + phenotype to K -phenotype were all uncapsulated. They exhibited neither K + type-specific precipitation line in an immunodiffusion test nor ladder-like banding pattern characteristic for bacterial acidic polysaccharides in polyacrylamide gel electrophoresis. Their virulence to Japanese flounder was highly attenuated. In contrast to the mutant strains, the parent capsulated strain resisted phagocytic and bactericidal activities of the macrophages and prevented chemiluminescence reaction of the macrophages upon phagocytosis. From these results, it is verified that the S. iniae capsule is an important factor for intramacrophage survival of the pathogen.

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2010

Fish Disease

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Serological Characterization of Streptococcus iniae Strains Isolated from Cultured Fish in Japan

Abstract: ABSTRACT-Streptococcus iniae is known as an important marine and freshwater fish pathogen worldwide. In this paper, we characterized two serological phenotypes in Japanese S. iniae isolates, mainly from Japanese flounder Paralichthys olivaceus.

Cited by 14 publications

References 49 publications

Role of Capsule in Immunogenicity of Streptococcus iniae to Japanese Flounder Paralichthys olivaceus

Role of Capsule in Immunogenicity of Streptococcus iniae to Japanese Flounder Paralichthys olivaceus

Virulence Attenuation of Capsular Polysaccharide-deleted Mutants of Streptococcus iniae in Japanese Flounder Paralichthys olivaceus

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