IMPROVEMENT OF LABORATORY DIAGNOSTICS OF CHOLERA DUE TO GENETICALLY ALTERED (HYBRID) VARIANTS OF CHOLERA VIBRIO BIOVAR EL TOR

Abstract

Aim. Improvement of laboratory diagnostics of cholera taking into the account appearance of hybrid variants of cholera vibrio El Tor biovar in the 1990s. Materials and methods. Phenotypic and molecular-genetic properties of typical toxigenic (151 strains) and hybrid (102 strains) variants of El Tor biovar cholera vibrios, isolated in the Caucuses in 1970 - 1990 and 1993 - 1998, respectively, were studied. Toxigenicity gene DNA fragments, inherent to El Tor biovars or classic, were detected by using a reagent kit «Genes of Vibrio cholerae variant ctxB-rstR-rstC, REF» developed by us. Results. Reagent kit «Genes of V. cholerae variant ctxB-rstR-rstC, REF» is proposed to be used for laboratory diagnostics of cholera during study of material from humans or environmental objects and for identification of V. cholerae O1 on genome level in PCR-analysis as a necessary addition to the classic scheme of bacteriological analysis. Conclusion. Laboratory diagnostics of cholera due to genetically altered (hybrid) variants of cholera vibrio El Tor biovar is based on a complex study of material from humans and environmental objects by routine bacteriologic and PCR-analysis methods with the aim of detection of gene DNA fragments in the studied material, that determine biovar (classic or El Tor), identification of V. cholerae О1 strains with differentiation of El Tor vibrios into typical and altered, as well as determination of enterotoxin, produced by the specific cholera vibrio strain (by the presence ctxBEl or ctxBcl gene DNA fragment, coding biosynthesis of CT-2 or CT-1, respectively).

Keywords

• laboratory diagnostics of cholera
• detection and identification of typical toxigenic and hybrid variants of el tor biovar