1999 Fiscal Year Final Research Report Summary
Virulence, infection, and pathogenicity related genes of fish pathogens
| Project/Area Number |
10460085
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
AOKI Takashi Tokyo University of Fisheries, Faculty of Fisheries, Professor, 水産学部, 教授 (00051805)
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| Co-Investigator(Kenkyū-buntansha) |
HIRONO Ikuo Tokyo University of Fisheries, Faculty of Fisheries, Assistant Professor, 水産学部, 助手 (00270926)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Virulene gene / Fish pathogen / Pasteurella piscicida / Lactococcus garivieae / Edwardsiella tarda / Vibrio / genome analysis |
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| Research Abstract |
In this study, we analysed the virulence related genes of Pasteurella piscicida, Lactococcus garvieae, Edwardsiella tarda, Vibrio anguillarum and V. parahaemolyticus.
Genome analysis was conducted to detect the virulence genes in P. piscicida KP9038. We have sequenced the both ends of approximately 900 clones. As a result of comparisons of these clones to the GeneBank database, it was determined that there are 13 toxin related genes, and 6 capsule and LPS synthesis genes. Characteristics of some of these virulence related genes have not detected in vitro. These results suggest that P. piscicida may express several virulence related genes only in vivo.
Five different clones were isolated from the gene library of the L garvieae SA8201 (KG-) strain by immunological screening using rabbit serum against L. garvieae (KG-) phenotype cells. The amino acid sequences of the immunologically detected proteins were homologous to a processing protease, dihydropteroate synthase, trigger factor, N-acetylglucosamine-6-phosphate deacetylase, and anti-phagocytosis M protein. Five genes were specifically expressed in the virulence KG- phenotype strains.
The eth hemolysin gene locus of E. tarda encodes the hemolysin EthA protein and its accessory protein EthB. We constructed mutants by site-directed marker insertion mutagenesis in ethA or ethB. Both the ethAィイD1-ィエD1 and ethBィイD1-ィエD1 mutants lacked extracellular, cell-associated, and intracellular hemolytic activities. The pathogenicity of these single gene mutants became weaker than that of original stain.
Chitinase genes from V. anguillarum KV9001 and V. parahaemolyticus ATCC17802 were cloned. The deduced amino acid sequences of these genes have 71.6% identity. The vac gene was highly prevalent in V. anguillarum, and the DNA probe of the vac gene hybridized to V. alginolyticus and Beneckea proteolytica DNA. The DNA probe of the vpc gene hybridized to V. alginolyticus, V. harveyi, and V. ordalii DNA.
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