Comparative analysis of MLVA25-typing and MLVA7-typing for their ability to identify focal affiliation of Yersinia pestis strains exemplified by isolates from the Central Caucasus highland natural plague focus

Abstract

Comparative analysis of MLVA25-typing and MLVA7-typing for their ability to identify focal affiliation of the Yersinia pestis strains have been performed on the basis of the bv. Medievalis isolates obtained from the Central Caucasus highland natural plague focus. For purposes of analysis, MLVA25 genotypes were identified for 82 isolates and further introduced into a database containing data on the 949 strains of the plague-causing agent obtained in other natural foci in Russia and countries within the former Soviet Union and beyond. The dendrograms were reconstructed by the UPGMA method with a categorical coefficient using data on all 25 VNTR loci or on only 7 of them, which were recommended by the experts from the Microbe Russian Research Anti-Plague Institute to be used for Y. pestis strains differentiation by their focal affiliation. The results of the analysis indicate the higher possibility of diagnostic errors when using the MLVA7-typing for distinguishing between the Y. pestis strains and suggest that it should be useful to subdivide the Central Caucasus highland plague focus into two subfoci.