Summary of Research Project Results under JSPS FY2001
"Research for the Future Program"

1.Research Institution Osaka University
2.Research Area Life Sciences
3.Research Field Infectious Diseases and Bioregulation
4.Term of Project FY 1997 〜 FY 2001
5.Project Number 97L00704
6.Title of Project Combined Control Strategy for Mucosal Bacterial Infections

7.Project Leader
Name Institution,Department Title of Position
Takeshi HONDA Osaka University, Research Institute for Microbial Diseases Professor

8.Core Members

Names Institution,Department Title of Position
Taiji NAKAE Tokai University, School of Medicine Professor
Shigeyuki HAMADA Osaka University, Graduate School of Dentistry Professor

9.Summary of Research Results

< HONDA Team > We conducted following experiments on 3 major bacterial intestinal pathogens and found: (1) Cortactin and tain, both of which are host cell molecules, are recruited beneath the EPEC-adherence sites and played an important role for EPEC-induced pedestal formation in infected cells. (2) TDH toxin produced by Vibrio parahaemolyticus exhibits enterotoxic activity (Cl- secretion) via activation of protein kinase, Ca++-influx and Ca++-activated Cl- channel. (3) We discovered a new foodborne infection attributed to Providencia alcalifaciens, which has invasive character.
< NAKAE Team > To elucidate xenobiotic extrusion mechanism by the MexAB-OprM efflux pump, we carried out the following experiments. (i) We destroyed mexA, mexB and oprM by the gene replacement and found that all the subunits are essential for the pump function. (ii) The subunit exchange experiments between several RND-family pumps revealed that the inner membrane subunits selects the substrates. (iii) Topological localization of MexA, MexB and OprM has been analyzed and the results revealed that MexA and OprM were lipoprotein ancholing the inner and the outer membrane, respectively, and both proteins were exposed to the periplasmic space. MexB appeared to have 12 transmembrane domains and 2 large periplasmic domains. These findings provided important information in understanding of the xenobiotic efflux and self defense and for designing drugs, which combat with efflux pump.
< HAMADA Team > (1)Antigen-specific antibodies were induced in the sera of FBP54-immunized mice, which survived significantly longer following the challenge with GAS (Group A Streptococcus) strain than did nonimmunized mice. (Infect. Immun. 2001) , (2) Internalization of GAS in epithelial cells is necessary and sufficient for the induction of apoptosis, which is initiated by mitochondrial dysfunction. (Cell. Microbiol. 2001)
(3) Administrations of superantigens protected mice from infection with Listeria, which was dependent on the enhanced Listeria-specific CTL activity in the presence of CD4 T cells. (Infect. Immun. 2001), (4) Fibronectin-binding protein, Fba, is an invasin of GAS, and an Fba-deficient mutant showed low mortality in mice following challenge infection, while laminin-binding protein, Lbp, functions as an adhesin. (Mol. Microbiol. 2001 & Infect. Immun. 2002)

10.Key Words

(1)EHEC、EPEC、(2)Vibrio parahaemolyticus、(3)Providencia
(4)Antibiotics、(5)Efflux pump、(6)Pseudomonas
(7)Group A Streptococcus、(8)Virulence factor、(9)Mucosal immunity