Brucella melitensis, a latent "travel bacterium," continual spread and expansion from Northern to Southern China and its relationship to worldwide lineages

Emerg Microbes Infect. 2020 Dec;9(1):1618-1627. doi: 10.1080/22221751.2020.1788995.

Abstract

Brucellosis caused by Brucella melitensis is considered to be one of the most important zoonotic diseases in China. In this study, Conventional bio-typing, MLVA (multiple locus variable-number tandem repeat analysis), and WGS (whole-genome sequencing)-SNP (single nucleotide polymorphism) were used to study the genetic similarity of B. melitensis in northern and southern China and analyze its relationship with worldwide lineages. Currently, the distribution of species/biovars of B. melitensis has obviously changed, and B. melitensis has become the dominant species in southern regions of China. Strains from the southern had a common geographic origin with strains from the northern. Many MLVA-16 events were shared in the genotypes of the southern and northern strains, suggest that genotypic movement occurred from north to south. Based on WGS-SNP analysis, strains from different provinces were closely related and may have descended from one common ancestor, suggests that the southern strains originated from northern China. These data indicate that B. melitensis is a latent "travel bacterium" that spread and expanded from North China to South China. Moreover, B. melitensis strains from China are also genetically related to strains from other Asian regions (Kazakhstan, Russia, Mongolia, and India). The movement of infected sheep and their products requires control.

Keywords: Brucella melitensis; China; MLVA; WGS-SNP; genetic relatedness; species/biovars.

MeSH terms

  • Animals
  • Brucella melitensis / classification*
  • Brucella melitensis / genetics
  • Brucella melitensis / isolation & purification
  • Brucellosis / microbiology*
  • Brucellosis / veterinary
  • China
  • Genome, Bacterial
  • Genotype
  • High-Throughput Nucleotide Sequencing
  • Humans
  • Minisatellite Repeats
  • Multilocus Sequence Typing / methods*
  • Phylogeny
  • Polymorphism, Single Nucleotide
  • Sheep
  • Sheep Diseases / microbiology*
  • Whole Genome Sequencing / methods*
  • Zoonoses / microbiology

Grants and funding

This study was supported by National Key Research and Development Project (No. 2019YFC1200705), the China Mega-project for Infectious Disease (Nos. 2017ZX10303401, 2018ZX10734401, and 2018ZX10734404), and the Natural Science Foundation of Inner Mongolia Autonomous Region of China (No. 2018MS08004). The funding agencies had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.