腸チフス菌内毒素に關する研究

特にVi抗原について

抄録

The so-called Boivin-type antigen (CF) was extracted from the bacillary body of Vi-type typhoid bacilli with N/4 trichloracetic acid and submitted to the following experiments for the study of Vi-antigen.
1) The toxicity of CF was reduced by the action of f ormalin f or 4 days at pH 7.8 and 37°C, contrary to the other endotoxins so far examined. The antigenicity of Vi-antigen, however, remained unchanged.
2) The fraction of CF, precipitated by Rivanol, had approximately the same property of the original CF, and retained high toxicity and antigenicity, The supernatant fluid had only slight toxicity and antigenicity.
3) The fraction of CF, precipitated by potassium alum, had lesser toxicity but more distinguished antigenicity in comparison with the fraction precipitated by Rivanol. The supernatant fraction was free from Vi-antigen and contained O-antigen alone. The amount of toxic and antigenic substance in the supernatant fluid was so small that the greater part of CF-antigen could be regarded to be present in the precipitate. This represented a noteworthy contrast to the fact, that the CF-antigen, derived from Strain O-901, was not precipitated by potassium alum.
4) Digestion with trypsin or pepsin reduced the toxicity of CF-antigen below a half of that of the original antigen. Although the Vi-antigen was still demonstrable in the digestion product by means of a precipitation test, it failed to stimulate the production of Vi-antibody, because the Vi-antigen was haptenized. The digestion product was inferior to the original CF in its capacity of the protection against infection. These results indicated a protein nature of the Vi-antigen.
5) From the floccule, produced by the addition of anti-Vi and anti-O sera to CF, Vi-antigen was recovered as a haptene and O-antigen as a perf ect antigen by means of the digestion procedure with trypsin. By the combination of both components, however, the Vi-antigen could not be reproduced as a perfect antigen.