MOLECULAR-GENETIC PROPERTIES OF VIBRIO CHOLERAE EL TOR STRAINS CIRCULATING IN AFRICA.

The review contains some brief information on cholera epidemics in Africa. Based on the results of the whole genome sequencing of 30 clinical strains isolated in Africa in different periods of the 7th cholera pandemic (1985-2012), extensive genetic diversity has been revealed. It is demonstrated that at present cholera epidemics in Africa are caused by new variants of the agent, which emerged in South- Eastern Asia in consequence of not only new genes acquisition, but also genome alterations of pandemicity and pathogenicity islands.

[EVALUATION OF FUNCTIONAL FEATURES AND STRESS RESISTANCE OF ISOGENIC TOXIGENIC AND NON-TOXIGENIC BIOVAR EL TOR VIBRIO CHOLERAE STRAINS].

Aim: Comparative evaluation of functional features of toxigenic biovar El Tor Vibrio cholerae strains and their spontaneous non-toxigenic mutants and study of their resistance to saline and oxidative stress.

Materials And Methods: 8 biovar El Tor V. cholerae strains were studied: 4 clinical strains isolated in 1970 from patients in Astrakhan and 4 spontaneous non-toxigenic mutants of these strains that have lost cholera toxin genes as a result of residence in river water at the temperature of 25°C.

Molecular-genetic peculiarities of classical biotype Vibrio cholerae, the etiological agent of the last outbreak Asiatic cholera in Russia.

Molecular-genetic properties of classical biotype Vibrio cholerae strains that caused the Asiatic cholera outbreak in 1942 in Russia have been investigated for the first time. Being characterized by high-level production of cholera toxin and toxin-coregulated adhesion pili both of which are the major virulence factors, all the strains studied, in contrast to the typical cholera pathogens, were autographic requiring purine and/or amino acids added to the minimal medium for their growth. Moreover, these strains containing the structural gene hapA, as shown by the polymerase chain reaction, produced no soluble hemagglutinin/protease, which enables the vibrios to get disseminated in the environment.

[Differences in virulence genes in Vibrio cholerae eltor strains isolated from different sources in Turkmenistan territory].

Polymerase chain reaction (PCR) detected the presence of various genes associated with virulence in genome of strains V. cholerae eltor isolated in Turkmenistan territory during epidemic and epidemic-free perios. It was found that a complete set of virulence genes (ctxA+, tcpA+ and toxR+) contained strains isolated from patients, carriers and environment only in cholera epidemics.

[Characterization of Vibrio cholerae eltor isolates according to their epidemic potential using new diagnostic cholera bacteriophages eltor ctx+ and ctx- and by the polymerase chain reaction].

The epidemic potential of 113 V. cholerae eltor strains of different origin was determined with new diagnostic cholera bacteriophages eltor ctx+ and ctx-, as well as the test for hemolytic activity. Of these strains 50 were epidemically safe and 51 were epidemically dangerous, while the epidemic potential of 12 other strains could not be detected.