Immunochemical Studies on Shigella dysenteriae Lipopolysaccharides

Abstract

An investigation of the sugar composition of lipopolysaccharides derived froin ten well-defined Nhigellu dysenteriae serotypes and two Escherichia alculescens-dispar serotypes was carried out. All the lipopolysaccharides contained glucosamine, glucose, galactose, heptose and 3-deoxyoctulosonic acid. These sugars were considered to represent the core polysaccharide and the same sugars except heptose and 3-deoxyoctulosonic acid, may represent the constituents of the O-specific polysaccharide chains. I n addition to the "basal" sugars, the following monosaccharides were detected as components of the various Sh. dysenteriae lipopolysaccharides : galactosamine, mannose, fucose, rhamnose and 3,B-dideoxyhexose. As a result, a chemical classification of Sh. dysenteriae lipopolysaccharides into eight cliemotypes was suggested. The sugar composition of li popclysaccharides from serologically related Shigella and Escherichiu species was compared and several cross-reacting pairs were found to belong to the same chemotype. The bacterial cultures were tested for purity by slide agglutination tests with the adsorbed type sera and by cultivation on the appropriate media. All the microorganisms were in active S-form and did not agglutinate spontaneously upon boiling. Their serological and biochemical characteristics proved to be typical. The exception was strain 5Q 1030 which was considered to be a wild R-mutant related to serotype 5 and which formed colonies of O-ring type on solid media. The living culture of SQ 1030 did not inhibit the 0-agglutination reaction of serotype 5 and agglutinated spontaneously on heating.Antisera were prepared by repeated immunisation (3-4 times) of rabbits with increasing doses of living cultures. For preparation of microbial cells the broth cultures (4 h) were inoculated into agar with casein hydrolysate. 30 gels of each strain were incubated for 18 to 20 h a t 37 "C. The gels were harvested by gentle shaking with saline containing Eur. J. Biochem. 40 (1973)

Somatic Antigen of Shigella dysenteriae Type 3. Structural Features of Specific Polysaccharide Chain

“…dysenteriae type 3. Unlike the previous results [2], the present data showed that the new individual chemotype corresponds to serotype 3. It is quite possible that new sugars might be discovered in the course of chemical investigation of Sh.…”

“…Recently, we have shown that the lipopolysaccharides of all ten serotypes could be divided into eight different chemotypes according to their qualitative monosaccharide composition [2]. This difference in chemical composition of 0-antigenic lipopolysaccharides is considered to be the cause of weak intergroup serological linkages among bacteria of Sh.…”

“…Passive haemagglutination tests were performed with sheep erythrocytes as described in previous paper [2]. Inhibition of passive haemagglutination reaction was carried out at a successive dilution of antiserum containing two haemagglutinating units according to the standard procedure [6].…”

Somatic Antigens of Shigella

“…Passive haemagglutination tests and inhibition of passive haemagglutination reaction were carried out at a successive dilution of antiserum containing two haemagglutinating units with sheep erythrocytes, sensitised by lipopolysaccharide, and antiserum against the live and autoclaved culture [4].…”

“…dysenteriae lipopolysaccharides, we have performed the chemotyping of all ten lipopolysaccharides of this subgroup [4], determined the structures of polysaccharide chains of serotypes 3 [5,6] and 6 [7], and discovered a new type of acidic monosaccharides [8] which were found to be the components of these O-antigens.…”