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.     

Chemotaxis of cholera vibrios: a study method and the relation to different substances

The chemotaxis of V. cholerae in response to 56 different substances (amino acids, carbohydrates, salts, etc.) has been studied by the methods of visual observation and quantitative determination. Attractants, neutral substances and one repellent have been revealed. Adler's method (1973) has been modified with regard to the requirements for the working procedures in handling the causative agents of highly dangerous infections.     

A probability matrix for the identification of vibrios

A probability matrix for computer-assisted identification of vibrios has been constructed, based on the API 20E system. Data were gathered from 173 strains representing 31 taxa of vibrios and related organisms, from a variety of sources. The matrix was tested internally by four statistical programs. Program OVERMAT tested the separation and program MOSTTYP the discretion and homogeneity of the taxa. Most of the taxa were satisfactory but a few were less so; reasons for this are discussed. Program CHARSEP and program DIACHAR tested the separation and diagnostic values, respectively, of the characters used. The overall test error was 4.5%. The matrix was assessed externally by its performance in the identification of vibrio-like strains isolated from freshwater. Of 243 wild strains, 79.4% were identified with ten taxa, with a Willcox score of greater than or equal to 0.99.     

A probability matrix for the identification of vibrios

A probability matrix for computer-assisted identification of vibrios has been constructed, based on the API 20E system. Data were gathered from 173 strains representing 31 taxa of vibrios and related organisms, from a variety of sources. The matrix was tested internally by four statistical programs. Program OVERMAT tested the separation and program MOSTTYP the discretion and homogeneity of the taxa. Most of the taxa were satisfactory but a few were less so; reasons for this are discussed. Program CHARSEP and program DIACHAR tested the separation and diagnostic values, respectively, of the characters used. The overall test error was 4–5%. The matrix was assessed externally by its performance in the identification of vibrio-like strains isolated from freshwater. Of 243 wild strains, 79–4% were identified with ten taxa, with a Willcox score of ζ 0–99.     

A facile analytical method for the identification of protease gene profiles from Bacillus thuringiensis strains

Five pairs of degenerate universal primers have been designed to identify the general protease gene profiles from some distinct Bacillus thuringiensis strains. Based on the PCR amplification patterns and DNA sequences of the cloned fragments, it was noted that the protease gene profiles of the three distinct strains of B. thuringiensis subsp. kurstaki HD73, tenebrionis and israelensis T14001 are varied. Seven protease genes, neutral protease B (nprB), intracellular serine protease A (ispA), extracellular serine protease (vpr), envelope-associated protease (prtH), neutral protease F (nprF), thermostable alkaline serine protease and alkaline serine protease (aprS), with known functions were identified from three distinct B. thuringiensis strains. In addition, five DNA sequences with unknown functions were also identified by this facile analytical method. However, based on the alignment of the derived protein sequences with the protein domain database, it suggested that at least one of these unknown genes, yunA, might be highly protease-related. Thus, the proposed PCR-mediated amplification design could be a facile method for identifying the protease gene profiles as well as for detecting novel protease genes of the B. thuringiensis strains.     

Monoclonal antibodies to antigens of cholera vibrios of the Ogava serovar

A set of hybrids is obtained synthesizing monoclonal antibodies to the surface antigenic determinants of the choleric vibrio of the Ogava serovar. The antigenic structure of vibrios of the typical and atypical strains isolated from a man and from environmental objects is studied using a collection of highly specific immunoglobulins. The high-specific diagnostic preparations for identification of the 01-group cholera agent serovar may be created on their base.     

Determination of the degree of similarity of cholera and NAG vibrios

The numeric taxonomy taking into account 80 signs has demonstrated the similarity of NAG and cholera vibrios, the average similarity coefficient exceeding 80 %. Among NAG vibrios, 53 % of the strains have been found to deviate from the central strain of V. cholerae mainly with regard to their utilization of the sources of carbon. The use of the citrate sign for the study of the biological properties of NAG vibrios is proposed.     

The use of a molecular hybridization method for studying the enterotoxigenic properties of Salmonella

The occurrence of the tox gene among 320 Salmonella strains of 23 serovars, differing in their origin, sensitivity to antibiotics, the presence of R-plasmids and a number of biochemical properties, has been studied by the method of DNA-DNA hybridization in situ. Essential differences in the occurrence of the tox gene have been detected both among S. typhimurium hospital strains and strains isolated in sporadic diseases, from the environment, from animals and among salmonellae belonging to different serovars. The direct correlation between the presence of the enterotoxigenicity gene and plasmids controlling resistance to antibiotics in Salmonella strains has been established. The expediency of using the method of gene probing for the study of the enterotoxigenic properties of salmonellae has been substantiated.