Genotyping of Yersinia pestis: variability of locus (CAAA)n in natural strains isolated in territory of former SSSR

Genome polymorphism by the locus (CAAA)n was studied in 69 strains of Yersinia pestis isolated from natural foci of the former Soviet Union. The polymorphism was found to be represented by ten alleles in chromosomes, which could be regarded as evidence of variability of this VNTR-locus (diversity index, DI = 0.86). The value of DI was found to vary substantially: from 0.24 in a group of vole strains from seven isolates from the Transcaucasian highlands to 0.77 in nine strains from the Central Asia desert focus. The allele polymorphism of the variable locus (CAAA)n in natural strains of Y. pestis was suggested to be used as a possible genetic marker of the strain. It was concluded that the oligonucleotide primers used in polymerase chain reaction should be upgraded to the genotyping accuracy.