The present paper deals with W-V variation of
Salmonella typhi Ty 2 strain. A variant W
0' 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 V
1 on the agar plate and that the colonies of W
0' 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 W
0' organisms deficient of Vi capsule and V
1 organisms possessing it.
W
0' variant is separated from V
1 in such a manner that the organisms of V
1 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 W
0' organisms is again centrifuged at a high speed. The purified W
0' organisms thus obtained from the colony of W
0' 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.
W
0' organisms, therefore, are exactly the same as the organisms of W-form of Ty 2 strain except that V
1 variant is constantly produced from W
0' 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 W
0' organisms. So that, Vi organisms are produced also in the colony of W
0' 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 W
0' 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.
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