Molecular-Genetic Analysis of Vibrio cholerae El Tor Strains of Epidemic Risk Isolated in Siberian and Far East Regions of Russia

摘要

PCR detection of biovar specificity and pathogenicity determinants has been performed in order to analyze the structural components of the genome of V. cholerae El Tor strains (n = 90) isolated during epidemic outbreaks in Siberia and the Far East, and the nucleotide sequence of the ctxB gene and the structure of ctxAB gene promoter region have been determined. As a result, toxicogenic strains V. cholerae El Tor were divided into two groups: the first group contained strains isolated at the initial stages of the seventh pandemia (in the 1970s), and they had the genotype ctxB3~+rstR~(El+) rstR~(Cl-)rstC~+TCL~+tbr_4; all El Tor vibrios posing an epidemic risk isolated in the 1990s were characterized as atypical variants due to ctxB gene harboring of the classical genotype (ctxB) in their genome and were placed in the second group. The second group fell into three genotypes according to the set of tested genetic markers (ctxB, rstR, rstC, TLC, and tbr) and affect certain territories. The established variability of the genome structure of Vibrio El Tor atypical variants may serve as a marker for molecular and epidemiological analysis of cholera entry pathways and distribution and is useful for speculating on the most likely directions of pathogen evolution.