Petrenko O. Biological and molecular genetic properties of cholera and parahemolytic vibrios isolated in Ukraine

The thesis is dedicated to the research of molecular biological properties of diarrheagenic pathogens of human vibrioses – Vibrio cholerae O1, V. choleraе non O1 and V. parahaemolyticus, isolated from patients during and between outbreaks of infections in Ukraine and the enhancement of their identification methods by major genetic determinants of pathogenicity. Comprehensive molecular biological analysis of cholera vibrios strains showed variability in their biological properties. Virulent strains of V. cholerae O1 are characterized by stable biological properties and have several major pathogenic genes. In avirulent strains of V. cholerae O1 a variability in hemolysis, agglutination and lysis properties is observed. There is also variation in genes rstC, rstR, tcpA in virulent strains and genes wbeT, mshA, tcpA in avirulent strains of V. cholerae O1. Strains of V. cholerae non O1 constitute a homogenous population. We have found variability in genes mshA, toxR, hapA. Among other genes, hly and rtxС are found to be the most conservative, regardless of their virulent properties and serogroups. We showed that strains of V. parahaemolyticus reveal their properties because of the production of thermally stable direct hemolysin TDH, which is coded by the tdh gene and is a major pathogenic factor in parahemolytic vibrios. Using the results of this research, we enhanced the PCR method scheme of identification of cholera and parahemolytic vibrios.