RESUMEN
Objective: To study the clustered regularly interspaced short palindromic repeats (CRISPR) loci polymorphism of Yersinia pestis and its area distribution in Gansu province. Methods: A total of 203 strains of Yersinia pestis isolated from 1962 to 2014 were selected for the culture and extraction of DNA. Three pairs of CRISPR primers were used to amplify the strain DNA by PCR, and the PCR products were sequenced. The groups and genotypes of strains were determined according to the spacer and spacer arrangement of CRISPR loci in the strain. Cluster analysis was done by using the software BioNumerics 5.10. Results: A total of 16 spacers, including 9 species of YPa loci, 4 species of YPb loci and 3 species of YPc loci, were found in the 203 strains of Yersinia pestis. A new spacer of a1' was found. The 203 strains were divided into 5 CRISPR genotypes and classified into 5 CRISPR clusters (Cb2, Ca7, Ca7', CaΔ5' and Ca35'). Each cluster showed significant area-specific characteristics, Cb2 was mainly distributed in Huining country and Pingchuan district, Ca7 was mainly found in Aksai Kazak autonomous country, Ca7' was mainly found in Xiahe country, Ca35' was mainly found in Subei Mongolia autonomous county and Yumen city and CaΔ5' was mainly distributed in Sunan Yugur autonomous county. Conclusions: The strains from different plague foci in Gansu were distinguished by CRISPR, all kinds of clusters showed the obvious area specific characteristics. It is important to study the evolution of Yersinia pestis in Gansu and trace the molecular biology origin of human plague.