[Molecular-genetic analysis of the epidemical strains of the Vibrio cholerae El Tor isolated from the Siberian and maritime regions of Russia].

The detection of the biotype-specificity, pathogenicity determinants, and sequencing of the ctxB gene and the ctxAB promoter was carried out for analysis of the Vibrio cholerae El Tor strains genome structure. The strains (n = 90) were isolated during cholera epidemic outbreaks in Siberia and the Far East. All toxigenic Vibrio cholerae El Tor strains were divided into two groups: the first group included strains isolated during 1970s: they had the genotype ctxB3+rstREl+rstRCl-rstC+TLC+tbr4. All epidemic dangerous El Tor biotype strains isolated in 1990s belonged to the second group. The strains were characterized as atypical variants because of classical genotype (ctxB1) ctxB gene harboring. The second group fell into three genotypes according to the set of genetic markers (ctxB, rstR, rstC, TLC, tbr). It was suggested that the set of genetic determinants could be used as a marker for epidemiological analysis of spreading of atypical ET strains. The comparative analysis of genome structure enables to suggest possible ways of pathogen evolution.