CHEMICAL ANALYSIS 



521 



TABLE 34 



Chemical Classification of the Vibrio Group, according to Linton and 

 HIS collaborators. 



have shown that strains belonging to chemical Groups I and VI have a high rate of respira- 

 tion and of aerobic glycolysis ; strains of Group II are moderately active, and those of 

 Group III relatively inactive ; strains of Groups IV and V have a high respiration but 

 a low aerobic glycolysis rate. In phosphate-buffered peptone water the final Eh of strains 

 belonging to chemical Groups I, II, and VI is higher than of those belonging to Groups 

 III, IV and V (Seal and Mitra 1939). 



It is as yet too early to explain the antigenic behaviour of the Vibrio group in terms 

 of chemical structure. As will be seen from Table 34, true cholera vibrios fall into chemical 

 Groups I, II, IV and VI. In addition, it has been found by Linton, Mitra and Seal 

 (1938-39) that the transition of a true cholera vibrio from the smooth to the rough or 

 p variant state may be accompanied by a change in its chemical grouping, such as from 

 Group I to Group IV. Chemical and antigenic differences have also been observed in 

 cholera strains isolated from different stages of a given epidemic (Linton, Shrivastava, 

 Seal and Mookerji (1938-39). 



In this country Bruce White has studied various fractions from members of the 

 Vibrio group in particular relation to their antigenic structure. White (1935a) finds 

 that, just as in the Salmonella group, the transformation of the smooth to the rough phase 

 is accompanied by a loss of specific O antigens and the unmasking of a common rough 

 antigen. In consequence, many organisms that are antigenicaUy diverse in the smooth 

 state show a close similarity in the rough. White has established four rough antigenic 

 groupings. Rough Group A contains strains derived from Gardner and Venkatraman's 

 smooth O sub-group I ; rough Group B from smooth O sub-group II ; rough Group C 

 from smooth O sub-groups III and IV ; and rough Group D from unclassified smooth 

 O sub-groups. 



Variants in a further stage of degradation, known as p variants, have been described 

 by White (19346, 1935ff). Organisms of this tj'pe have lost their dominant rough O antigen, 

 and appear antigenicaUy similar owing to the unmasking of a stiU deeper common p antigen. 

 Little is yet known of the chemical structure of this p antigen, but it is very resistant to 

 proteolytic digestion, and includes a polysaccharide hapten referred to by White (1940c) 

 as Q6. 



A study of the different types of cholera vibrios belonging to Gardner and Venkatra- 

 man's sub-group I led Scholtens (1933) and Heiberg (19366) to postulate the existence 

 of two qualitatively distinct somatic antigens, A and B. Some strains appeared to con- 

 tain A only, and some both A and B. White (19376), on the other hand, following up 

 his work of 1936, disagrees with this interpretation. 



