Genetic characterization of Bacillus anthracis strains circulating in Italy from 1972 to 2018

PLoS One. 2020 Jan 13;15(1):e0227875. doi: 10.1371/journal.pone.0227875. eCollection 2020.

Abstract

In Italy anthrax is an endemic disease, with a few outbreaks occurring almost every year. We surveyed 234 B. anthracis strains from animals (n = 196), humans (n = 3) and the environment (n = 35) isolated during Italian outbreaks in the years 1972-2018. Despite the considerable genetic homogeneity of B. anthracis, the strains were effectively differentiated using canonical single nucleotide polymorphisms (CanSNPs) assay and multiple-locus variable-number tandem repeat analysis (MLVA). The phylogenetic identity was determined through the characterization of 14 CanSNPs. In addition, a subsequent 31-loci MLVA assay was also used to further discriminate B. anthracis genotypes into subgroups. The analysis of 14 CanSNPs allowed for the identification of four main lineages: A.Br.011/009, A.Br.008/011 (respectively belonging to A.Br.008/009 sublineage, also known Trans-Eurasian or TEA group), A.Br.005/006 and B.Br.CNEVA. A.Br.011/009, the most common subgroup of lineage A, is the major genotype of B. anthracis in Italy. The MLVA analysis revealed the presence of 55 different genotypes in Italy. Most of the genotypes are genetically very similar, supporting the hypothesis that all strains evolved from a local common ancestral strain, except for two genotypes representing the branch A.Br.005/006 and B.Br.CNEVA. The genotyping analysis applied in this study remains a very valuable tool for studying the diversity, evolution, and molecular epidemiology of B. anthracis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anthrax / epidemiology
  • Anthrax / genetics*
  • Anthrax / microbiology
  • Bacillus anthracis / classification
  • Bacillus anthracis / genetics*
  • Bacillus anthracis / pathogenicity
  • Genome, Bacterial / genetics
  • Genotype
  • Humans
  • Italy / epidemiology
  • Minisatellite Repeats / genetics
  • Molecular Epidemiology*
  • Phylogeny*
  • Polymorphism, Single Nucleotide / genetics

Grants and funding

The study was funded by Italian Ministry of Health, by a research program "Ricerca corrente IZS PB 005/15 RC" (www.salute.gov.it) to AF. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.