1991 Fiscal Year Final Research Report Summary
Analysis of Resistance Mechanism of Complement-resistant Bacteria
| Project/Area Number |
01480178
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
細菌学
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| Research Institution | Osaka University |
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Principal Investigator |
INOUE Kozo Osaka Univ. Med. Sch., Professor, 医学部, 教授 (10028300)
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| Co-Investigator(Kenkyū-buntansha) |
INAGI Reiko Osaka Univ. Med. Sch., Research Associate, 医学部, 助手
HONG Kyongsu Osaka Univ. Med. Sch., Research Associate, 医学部, 助手 (30158894)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Serum-resistant Bacteria / Phagocytosis / Bactericidal Activity / Staphylococcal M Protein / traT gene of R factor |
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| Research Abstract |
1. Streptococcal M protein inhibited significantly the alternative pathway C3 convertase of complement and the classical C5 convertase. Therefore, M protein intercepts the amplification circuit of C3b formation and also inhibits the formation of C5a, leading to suppressed expression of complement receptors (CR1 and CR3) on the phagocytic cells.
2. A murine monoclonal antibody was raised against the synthetic TraT peptide (86-99). This MoAb reated with only denatured TraT protein. Using this MoAb for monotoring TraT by immunoblotting, TraT protein was partially purified from solubilized membrane fraction of traT^+ bacteria. Six MoAbs were then generated against this protein. These MoAbs reacted with the native protein even on the living bacteria, and their Fab fragments suppressed the inhibiting effect of TraT protein on bactericidal activity of serum.
The purification method was established from solubilized bacterial membrane fraction by ion exchange and gel filtration chromatographies. The final preparation contained no endotoxin activity.
The purified TraT protein inhibited the lysis of sensitized erythrocytes by serum complement. Its inhibitory action was mainly on the C6 step. It also slightly inhibited the reaction steps of C4, C5 and factor B. However, TraT inhibited neither the cleavage of C5 nor the reaction of preformed C5b6 complex.
The TraT protein probably inhibits the formation of C5b6 complex or causes formation of structurally alterated, nonfunctional C5b6 complex.
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[Publications] Pramoonjago, P., M. Kaneko, T. Kinoshita, E. Otsubo, J. Takeda, K. Hong, R. Inagi, and K. Inoue.: "Role of TraT protein, an anticomplementary protein produced in Escherichia coli by R100 factor, in serum resistance." J. Immunol.148. 827-86 (1992)
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