| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1987: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1986: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
1.Genetic analysis of virulence factors of Shigella:(1)S.boydii large plasmid; We transferred the large plasmid in S.boydii 5 to the plasmid-cured strains of S.boydii,S.sonnei,and Escherichia coli.The transconjugants we obtained acquired the ability to penetrate tissue culture cells,indicating that a large plasmid in S.boydii is responsible for invasiveness.(2)Cloning of S. sonnei form I antigen genes;We cloned,using a cosmid vector,the DNA fragment which contained the genes encoding the synthesis of form I antigen.We constructed the physical map of plasmid pJK1137(36kb)and obtained transposoninserted mutants.From the anaylysis of insertion mutants,gene(s) encoding form I antigen synthesis was mapped in 2 fragments(ca.13db)which were cut with EcoRI,SalI,and hindII,
2.Host defense mechanisms against Shigella infaction:(1) Susceptibility of Shigella spp.to human serum;Difference among Shigella spp.in susceptibility to human serum was observed among clinical isolates of Shigella strains.Order of susceptibility to human serum was as follows;group A > group B > group C,B6 > group D.Analysis of serum treated with heat (56 c 30 min ,or 50 C 20 min) and of activation of complement by lipopolysaccharides (LPS) from each Shigella sp.suggested that the LPS composition,especially the 0 antigen polysaccharide chains,contributes to the difference among Shigella spp.in susceptibility to human serum.(2)Human serum immue response in shigellosis as determined by ELISA;The sera from dysentery patients showed sighificantly higher antibody titers against Shigella LPS,with IgA and IgM at around 7 days and IgG at around 12 days after onset of the disease,than those from healthy persons.IgA antibodies appeared more specific than IgG and IgM antibodies. Analysis of IgA antibody by sucrose gradient ultracentrifugation suggested that during an early convalescent stage of shigellosis serum IgA antibody response against Shigella LPS is largely polymeric.
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