Abstract
Bovine brucellosis is a re-emerging disease in South Korea with a recent increase in incidence on cattle farms in specific regions. Given this, a molecular phylogenetic investigation is a practical approach to tracking the infection source to reveal the reliable etiological evidence of the incidence. We analyzed phylogenetic characteristics using multi-locus sequence type analysis (MLSA) to prove the genetic correlation ofBrucella abortus strains isolated from two specific regions, Jeonnam (JN) and Gyeongnam (GN). We analyzed 81 B. abortus strains from domestic cattle in nine provinces within these two regions in the last three years using MLSA with 18 specific single nucleotide polymorphisms (SNPs) which could display phylogenetic characteristics from genome sequences verified by draft whole genome sequencing (WGS). Fifty-eight strains isolated from eight JN provinces were divided into two sequence types (STs), either ST3 or ST5. All 23 strains from the one province in the GN region belonged in only ST3. In comparison with 172 internal reference strains isolated from other regions, 49 strains from four (4/8) provinces of JN region and all strains from the GN province were classified as ST3, which accounts for 31.2% of the internal reference strains. Formation of this ST3 cluster in five specific provinces over the three year period indicated a considerable molecular epidemiological relationship among these areas. Accordingly, we found B. abortus strains having the same genotypes distributed in some specific regions that could circulate across certain areas by indigenous strains. Furthermore, we propose that this investigation will be an integral part of providing reliable genetic evidence to support an effective action plan to control disseminating the disease. Work supportedby APQA B-1543081-2021-22-02.
