Isolation of a cytotoxin from L-form Salmonella typhimurium |
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Authors: | Eiji Kita Noriaki Kamikaidou Akira Nakano Shuzo Kashiba |
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Institution: | Department of Bacteriology, Nara Medical University, Kashihara, Nara, Japan |
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Abstract: | Abstract A cytotoxin protein was isolated from the sodium dodecyl sulphate (SDS)-solubilized extract of the stable L forms of Salmonella typhimurium by ion-retardation chromatography, ion-exchange chromatography, isoelectric focusing and gel filtration. The purified toxin, with a molecular mass of 32 kDa and with isoelectric point of 6.4, was thermolabile and trypsin-sensitive. Against mouse macrophages, its cytolytic effect was detectable in vitro at concentrations higher than 0.7 μg/ml, with a complete lysis obtained at 5 μg/ml. In contrast, it stimulated C3H/HeJ macrophages in the dose range of 0.1–0.5 μg/ml to allow the cell to respond to endotoxin, resulting in the significant production of tumor necrosis factor α. By Northern blot analysis, this effect was detectable at a dose as low as 0.01 μg/ml. These findings suggest that the transformation of bacillary S. typhimurium into L forms in vivo may induce alterations in host resistance against murine typhoid. |
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Keywords: | L-form Salmonella typhimurium Cytotoxin Tumor necrosis factor |
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