Construction of PCR Test-System for Differentiation between Genetically Altered Toxigenic Vibrio cholerae Strains, Biovar El Tor, with Varied Epidemic Potential

Abstract

Designed is a multi-locus PCR test-system that allows for differentiation between genetically altered Vibrio cholerae strains, biovar El Tor, with high and low epidemic potential respectively, based on identification of genetic marker structure in the agent of the seventh cholera pandemic-pandemicity island VSP-II. In the course of investigations selected have been three target genes allocated in the central region and terminal end of the mobile genetic element. This test-system offers the possibility to identify the strains containing intact VSP-II, the ones containing VSP-II with a short-length deletion, and the strains with VSP-II with extended deletion. The first two are classified as the variants with low epidemic potential, while the last ones-as the variants with high epidemic potential. Specificity and efficacy of the test-system is shown by the experiments with 28 toxigenic genetically altered V. cholerae strains, biovar El Tor, and 6 strains of closely related species and enterobacteria. The results obtained coincide with the data on mono-locus PCR assay and in a number of instances are verified by sequencing.