Abstract
The present paper deals with W-V variation of Salmonella typhi Ty 2 strain. A variant W0' obtained by low pressure cultivation from the Ty 2 strain of Salmonella typhi has characters exactly the same as those of the W-form of Ty 2 strain except that it produces a V-form variant V1 on the agar plate and that the colonies of W0' variant are apt to become irregular in size with growth and give a flower-like appearance by forming radiate opaque stripes. The striated colony consists of W0' organisms deficient of Vi capsule and V1 organisms possessing it.
W0' variant is separated from V1 in such a manner that the organisms of V1 are agglutinated by the addition of Vi antiserum and the agglutinated material is centrifuged at a low speed and the supernatant which contains a large number of W0' organisms is again centrifuged at a high speed. The purified W0' organisms thus obtained from the colony of W0' formed on the agar plate are devoid of Vi capsules. Accordingly, they are not agglutinated by Vi antiserum nor by a low pH concentration (lower than 3.25), and are low in virulence.
W0' organisms, therefore, are exactly the same as the organisms of W-form of Ty 2 strain except that V1 variant is constantly produced from W0' organisms when grown on culture media or probaly when grown in animal body.
In view of the above mentioned findings, it is concluded that Vi organisms are readily produced from W0' organisms. So that, Vi organisms are produced also in the colony of W0' following its growth and therefore the bacterial suspension prepared from the colony shows positive agglutination in either case of O or Vi antiserum in used giving an appearance as if the colony is a variant of VW-form. This phenomenon, further, demonstrates a W-V variation of Salmonella typhi which is regarded to be extremely rare or impossible to take place.
It was quite an interesting finding that almost no trace of Vi substance was detectable in individiums or in the suspension of purified W0' organisms demonstrating a picture completely different from so-called loss variation of the V-W variation. The present study will be supplemented by the second report.
