| Co-Investigator(Kenkyū-buntansha) |
MATSUI Hidenori The Kitasato Institute, Dep. Bacteriol. 2nd Lab., Senior Researcher, 細菌部第2室, 研究員 (30219373)
KAWAHARA Kazuyoshi The Kitasato Institute, Dep. Bacteriol. 2nd Lab., Subchief of Laboratory, 細菌部第2室, 室長補佐 (20195126)
MORIGUCHI Ryozo The Kitasato Institute, Dep. Pathol. 1st Lab., Chief of Laboratory, 病理部第1室, 室長 (30101299)
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| Research Abstract |
1. Correlation between virulence plasmid of Salmonella choleraesuis, pKDSC50, and its mouse virulence: S. choleraesuis strains harboring virulence plasmid, pKDSC50 (parent and re-introduced strains), and cured strains were inoculated intraperitoneally into ICR mice, and the mice were examined pathologically for 14 days. Parent and re-introduced strains caused bacteremia in mice, and inoculated bacteria were recovered from spleen and liver. Obvious pathological changes were observed at individual tissues of peritoneal fluid, mesenterium, and visceral organs, and those changes persisted to day 14. In contrast, mice infected with plasmid-cured strain showed no bacteremia, and had only mild and transient pathological changes at peritoneal fluid, mesenterium, and viscera.
2. Difference of cell surface components between pKDSC50-harbouring and -cured strains of S. choleraesuis : Lipopolysaccharide, outer membrane proteins, and phospholipids of parent, re-introduced, and cured strains were che
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mically and biochemically compared. There was no significant difference between them, indicating that pKDSC50 did not mediate the detectable change of bacterial cell surface.
3. Mapping of the region responsible for the ability to cause mouse bacteremia by transposoninsertional inactivation: Mouse bacteremia test was established in the base of the results of pathological study, and used for screening 100 mutant strains constructed by transposon Tnl-insertional inactivation. Plasmid DNA of mouse bacteremia test-negative strains were introduced to cured strain by transformation, and the transformants were again tested for mouse bacteremia ability. Nine strains were negative for the second test, and Tnl on their plasmids were localized in 6.2 kb region of pKDSC50. This region was designated mba region.
4. Genetical study on mba region of pKDSC50: DNA fragments of mba region were cloned in E. coli, and proteins encoded in this region were identified by E. coli minicell system, or by lac-promoter system with induction of isopropylthiogalactoside. Four proteins with apparent molecular weights of 29k, 70k, 32k, and 32k were detected, and open reading frames corresponding to these four proteins were found in mba region by nucleotide sequential analysis. Other research groups has recently reported similar proteins encoded in virulence plasmid of S. typhimurium, suggesting that the proteins we found were common among virulence plasmid-harboring Salmonella, and playing important role in pathogenesis of Salmonella. Less
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