Immunogenic complexes of the soluble surface antigens of Sh. sonnei]

The comparative study of the immunogenic properties of Sh. sonnei (phases I and II) soluble surface antigens obtained by the modified method of aqueous-saline extraction and Sh. sonnei (phase I) antigen obtained by Boivin's method was made with the use of the keratoconjunctival test in guinea pigs. The protective activity of a high molecular fraction obtained by the fractionation of phase I soluble surface antigens in Sepharose 4B was studied. Boivin's antigen, when used for immunization in optimum doses, was found to have pronounced protective properties, whereas phase II soluble surface antigens showed no protective activity. A high molecular fraction obtained from phase I soluble surface antigen was found to be the most immunogenic. Protective activity was largely connected with protein antigen. The question whether protein antigen was an independent protective antigen or whether it constituted a part of a complex which determined the protective activity of a high molecular fraction remained unsolved.     

Antigenic composition of different forms of Sh. sonnei]

Data are presented on the study, with the aid of immunophoresis, of the antigenic composition of the I, II phases and R-forms of Sh. sonnei. From 5 to 7 antigens differing by thermoresistance, electrophoretic and diffuse mobility were found in the composition of microbial cells of various forms Sh. sonnei. Differences between the I phase on the one hand and cells of the II phase and R-form, on the other hand, consisted both in the quantitative composition of components of their thermostable O-antigens and in the structure of specific lipopolysaccharides of the forms.     

Immunoelectrophoretic analysis of the antigenic structure of Sh. sonnei]

The authors studied the antigenic composition of 105 Sh. sonnei strains freshly isolated from patients suffering from acute dysentery and carriers. Immunophoregrams of pure S-and R-forms species were obtained. Up to 13 antigens differing by electrophoretic and diffusion mobility and immunological specificity were revealed among soluble Sh. sonnei antigens The position of common and specific antigens was determined on the immunophoregram. Along with the thermostable somatic O-antigen detected at the I phase of the S-forms, and two thermolabile O-antigen components at the II phase, and the R-forms, there was revealed a surface, relatively thermolabile, K-antigen of A-type capable of agglutinating live bacteria in the O-antiserum; position of the latter on the immunophoregram was also determined.     

Immunochemical findings about the high molecular weight surface antigens of Shigella sonnei]

The authors studied immunochemical properties of the high molecular fraction of surface soluble antigens obtained by extraction with salt solutions from Sh. sonnei (virulent strain 1041) dried with acetone. The high molecular fraction was isolated by gel-filtration on Sepharose-4B. Along with the O-somatic antigen, this fraction contained thermostable and thermolabile antigens resistant to trypsin and RNA-ase treatment, and also protein-containing antigens disintegrated by trypsin. In difference from the O-somatic antigen, one of the thermostable components was completely precipitated with 50% alcohol.     

Differential characteristics of the I and II phases and R-form of Sh. sonnei]

Characteristics of various phases of Sh. sonnei were determined on the standard strains of Sh. sonnei of phases I and II and R-form used for the industrial production of agglutinating monoreceptor sera. Bacteria of phase I displayed a distinct morphological, cultural and serological differences. For the differentiation of Sh. sonnei of the II phase and R-form, representing the greatest difficulty in this respect, it is recommended to use phages RFfm and 6-SR, and also indirect immunofluorescence method with the application of agglutinating monophasic serum against the II phase of Sh. sonnei. In addition, a study was made of over 20 various Sh. sonnei strains at different dissociative process phases. Verification data completely confirmed the specificity of phages RFfm and 6-SR for Sh. sonnei in the II phase. The efficacy of the immunofluorescence method was confirmed on 6 strains.     

Electron microscopic study of the I, II phases and R-forms of Sh. sonnei]

Electron microscopic study of the microbial cells of the I, II phases and the R-form was carried out. Intact cells were examined by negative contrasting, and morphological differences of various bacterial phases were shown: cells of the I phase had a relatively smooth surface, bacteria of the II phase had a smooth surface, but many cell wall fragments were split from them; the surface of the R-form cells was coarse, folded, and cell wall fragments were split from the majority of bacteria. Antigenic determinants responsible for phasic specificity in bacteria of the I and II phases were located at some distance from the external membrane of the cell wall; as to the R-form cells--they were localized on the wall.     

Use of intraspecific differentiation of Sh. sonnei for the purpose of studying patterns in the epidemic process of dysentery]

The use of complex typing of Sh. sonnei by the colicinogenic and enzymatic properties in epidemiological analysis of dysentery caused by Sh. sonnei, apart from establishment of epidemiological connections in the foci, offered a possibility of introducing significant corrections in the determination of the sizes and duration of existence of the epidemic foci, as well as in detection of the sources and factors of transmission of the infection established in epidemiological examination. Typing of Sh. sonnei also aided in ascertaining that, apart from general regularities in the individual territories, the epidemic process in individual groups of the population and in different seasons of the year could also course autonomously.     

Biological activity of extracts isolated from a virulent strain of Sh. flexneri grown in the presence of calcium ions]

The authors carried out a comparative study of the genetically connected Sh. flexneri cultures (3 virulent strains, 3 clones of an avirulent mutant selected in the flux of an oblique light from the virulent strain, and lac+ Kcp A-hybrids obtained by crossing the initial virulent cultures with the E. coli K12 Hfr strains). The absence of any correlation between the virulence of the strains under study and the lipopolysaccharide (by rhamnose) content in the extracts from them in growing the cultures in the presence of calcium ions was noted. Toxicity of the extracts from the virulent cultures was demonstrated on a model of developing chick embryos. No such property was possessed by the extracts from avirulent strains. The extracts from the virulent cultures in nontoxic doses possessed the capacity to decrease LD50 of shigella strains used for the infection. The biologically active factor determined in the extracts from the virulent cultures apparently was not lipopolysaccharide.     

Soluble metabolic antigens of Trichinella spiralis: their isolation and characteristics]

Cultivation of Trichinella muscular larvae, purified by centrifugation in 20 ... 50% saccharose density gradient, in protein--free nutrient media at a dosage of 3.5-.10(3) lar./ml in the presence of insulin has made it possible to obtain a soluble antigen of Trichinella. It has been shown by means of electrophoresis in polyacrylamide gel that the soluble (secretory-excretory) antigen has three protein fractions while the somatic Trichinella antigen has 18 fractions. It has been shown that the soluble (secretory-excretory) antigen can be used for immobilization of erythrocytes on the surface that enables the sensitivity and specificity of serological methods for diagnosis of trichinellosis to be increased.     

Structure of shigella antigens. Heterogeneity of specific polysaccharides of 2 Shigella flexneri strains and 2 Sh. flexneri/Escherichia coli hybrids]

The S-specific polysaccharide from 2 Sh. flexneri wild strains (with serological var. X- and var. Y-specificity, respectively) and 2 Sh. flexneri E. coli hybrids (with the same specificities) can be separated by means of gel chromatography on Sephadex G-200 and G-50 into altogether 6 fractions per strain. Fraction G-200/1 (molecular weight greater than 10(6)D) represents a polymer consisting nearly exclusively of glucose and is present mainly in the two Y-type strains, much less in the two X-type strains. Fractions G-200/2 and G-200/3 (molecular weight approximately 10(5)D and approximately 2 - 10(4)D, respectively) seem to consist mainly of the S-specific side chains while fraction G-50/2 (molecular weight approximately 2000 D) presumably contains an SR-polysaccharide (core with one repeating unit.) Fraction G-50/3 (molecular weight approximately 100 D) contains the core polysaccharide and fraction G-50/4 splitting products (mainly KDO). No significant differences in chromatographical behaviour and quantitative composition could be found between the polysaccharides of the wild strains and the hybrid strains. Because of the well-known stability of the glucosaminyl linkages the sugar analysis was not only performed after acidic hydrolysis. In some cases the acid hydrolysate was reacted with HNO2 to cleave the glucosaminyl linkages. In most cases the values obtaines now were higher than those obtained directly.