Preservation of cholerogenicity in cholera vibrios in the incomplete L-cycle stage]

The work presents the characteristics of the forms appearing as a result of the incomplete L cycle of Vibrio cholerae obtained in experimental conditions after the cultivation of typical V. eltor strain, serovar Ogawa, for 5 months at room temperature in sterile river water without subculturing. The culture formed shaprly changed L-similar colonies, had decreased agglutinability and was resistant to diagnostic cholera phages, but retained its cholerogenicity for suckling rabbits. A suggestion was made concerning the possible epidemiological significance of such forms and the necessity of their detection in the course of bacteriological analysis for cholera.     

Phage typing of cholera vibrios with different sets of phages]

A comparative study was made of two sets of Mukerjee and Drozhevkina-Arutyunova's bacteriophages in typing 514 strains of the El Tor vibrios and 45 strains of clasic biotype. It was shown that the Mukerjee or Drozhevkina-Arutyunova's phages could be used for the typing of cholera vibrios. The phages of the latter set prove to detect more phage types (18 against 11); they determine both the phage type and the biotype at the same time. The typing of cholera vibrios of both biotypes is possible, and the percentage of nontyping strains left is comparatively low (5.2 against 23.5 after Mukerjee). A table of the phage correspondence was made; it permits to obtain comparable data in using any set of the typing phages.     

Ultrastructural changes in interneuron connections in intramural ganglia of the small intestine in suckling rabbits with experimental cholera]

Data, received in investigation of the small intestine intramural ganglia of 34 suckling rabbits show, that development of experimental cholera induce in the neurons reactive shifts, changed by dystrophic alterations. Prevaluation of cholinergic influences in autonomic ganglia in small intestine promotes enterocytes hypersecretion and accelerating of motor activity.     

Specificity of lectin receptors of cholera vibrios

Spectrum of carbohydrate specificity of lectin receptors of epidemically significant cholera vibrios (ctx(+) tcp(+) Hly(-)) as well as non epidemic hemolytic variants with or without tcp A gene (ctx(-) tcp(-) Hly(+), ctx(-) tcp(+) Hly(+)) was studied under the carbohydrates-mediated inhibition of hemagglutination between human erythrocytes of four blood groups and sheep erythrocytes. It was demonstrated that in toxigenic cultures lectin receptors specific for glucose, mannose, sacharose, lactose dominate whereas receptors specific for aminosugars are virtually absent. The latter are detected in hemolytic vibrios that can explain their ecologic flexibility.     

The agglutination reactions of cholera vibrios.

The present study with 11 strains of vibrio using single-dose and hyperimmune antisera confirmed earlier observations on the cross-reactivity of the flagellar (H) agglutinating antigens of cholera and NAG vibrios. The effect of several variables on the agglutinating sensitivity of cell suspensions was determined by measuring the reaction rate in the presence of constant O- or H-antibody. The variables investigated were culture conditions, antigen dilution, reaction temperature, formalin fixation and heat-treatment; all were found to affect cholera and NAG serovars similarly. The optimal conditions for the O- and H-tests were markedly different. Dilute, young living broth cultures were highly sensitive to O- but not H-antibody. Conditions favoring the H-reaction were 48-hr culture on firm dry agar, high suspension opacity, a reaction temperature of 45 C and formalin fixation. The inverse relationship of O- and H-sensitivity under these conditions indicated that the flagellar antigen in the growing vibrio is masked by an O-sensitive layer. The temperature of denaturation of the unfixed H-antigen before or after reaction with antiserum was 64 +/- 0.5 C and could be used as a criterion of the H-reaction.     

Long-term survival of E1 Tor cholera vibrios in naturally contaminated sewage]

El Tor cholera vibrios of Ogava serological type were revealed in the sewage of the locomotive shed for 15 months. In experiment with an oil catcher in naturally infected sewage El Tor vibrios survived 36 days, in storage of this sewage at the laboratory--39 days, in the artificially infected sewage of a settlement and of a milk plant--2 and 11 days, respectively, in the oil and disel fuel--14 months. Consequently, El Tor vibrio can survive in the sewage with a high oil product content for a long time.     

Analysis of the data in the literature on the sensitivity of cholera vibrios to tetracycline]

Variation diagrams were proposed to be used for the analysis of the published data on the study of Vibrio cholerae sensitivity to tetracycline. The diagrams provided systematization of dissimilar data of the experimental studies and a unique system of estimation was created. The analysis of the systematized data provided dividing of the Vibrio cholerae strains tested into 4 groups differing in the levels of their sensitivity to tetracycline. The groups were independent of the Vibrio cholerae biotypes and the place and period of the strain isolation.     

The suckling mouse model of cholera

Vibrio cholerae colonization of the suckling mouse intestine is a commonly used animal model for the human diarrheal disease cholera. This model has a number of advantages as well as disadvantages, and has been extremely useful in the identification and characterization of proven and putative virulence factors involved in human cholera.