Genetic diversity of KoreanBacillus anthracisisolates from soil evaluated with a single nucleotide repeat analysis

Abstract

Bacillus (B.) anthracis, the etiological agent of anthrax, is one of the most genetically monomorphic bacteria species in the world. Due to the very limited genetic diversity of this species, classification of isolates of this bacterium requires methods with high discriminatory power. Single nucleotide repeat (SNR) analysis is a type of variable-number tandem repeat assay that evaluates regions with very high mutation rates. To subtype a collection of 21 isolates that were obtained during a B. anthracis outbreak in Korea, we analyzed four SNR marker loci using nucleotide sequencing analysis. These isolates were obtained from soil samples and the Korean Center for Disease Control and Prevention. The SNR analysis was able to detect 13 subgenotypes, which allowed a detailed evaluation of the Korean isolates. Our study demonstrated that the SNR analysis was able to discriminate between strains with the same multiple-locus variable-number tandem repeat analysis genotypes. In summary, we obtained SNR results for four SNR marker loci of newly acquired strains from Korea. Our findings will be helpful for creating marker systems and help identify markers that could be used for future forensic studies.

Genetic source tracking of an anthrax outbreak in Shaanxi province, China

“…The SNR method with more polymorphism should be used for source tracking. Such methods could differentiate very closely related strains and could be useful molecular epidemiological tools in outbreak or bioterrorism events [15]. …”

“…A previous study showed that seven strains of B. anthracis recovered from Northeast China from 2010–2014 were distinguished as A.Br.001/002 ( n  = 5) or A.Br.Ames ( n  = 2) sublineages, and the two A.Br.Ames strains were further identified as same SNR pattern [13]. Because SNR markers can provide additional genetic resolution among B. anthracis strains of the same MLVA genotype [14, 15], the SNR analysis has therefore been used as a means of source tracking anthrax outbreaks [14]. …”