title: Whole-genome mapping reveals a large chromosomal inversion on Iberian Brucella suis biovar 2 strains.
abstract: Optical mapping is a technology able to quickly generate high resolution ordered whole-genome restriction maps of bacteria, being a proven approach to search for diversity among bacterial isolates. In this work, optical whole-genome maps were used to compare closely-related Brucella suis biovar 2 strains. This biovar is the unique isolated in domestic pigs and wild boars in Portugal and Spain and most of the strains share specific molecular characteristics establishing an Iberian clonal lineage that can be differentiated from another lineage mainly isolated in several Central European countries. We performed the BamHI whole-genome optical maps of five B. suis biovar 2 field strains, isolated from wild boars in Portugal and Spain (three from the Iberian lineage and two from the Central European one) as well as of the reference strain B. suis biovar 2 ATCC 23445 (Central European lineage, Denmark). Each strain showed a distinct, highly individual configuration of 228-231 BamHI fragments. Nevertheless, a low divergence was globally observed in chromosome II (1.6%) relatively to chromosome I (2.4%). Optical mapping also disclosed genomic events associated with B. suis strains in chromosome I, namely one indel (3.5kb) and one large inversion (944kb). By using targeted-PCR in a set of 176 B. suis strains, including all biovars and haplotypes, the indel was found to be specific of the reference strain ATCC 23445 and the large inversion was shown to be an exclusive genomic marker of the Iberian clonal lineage of biovar 2.
authors.affiliation: Instituto Nacional de Investigação Agrária e Veterinária, I.P. (INIAV, IP), Rua General Morais Sarmento, s/n, 1500-310 Lisboa, Portugal; Universidade de Lisboa, Faculdade de Ciências, Biosystems and Integrative Sciences Institute (BioISI), Edificio TecLabs, Campus da FCUL, Campo Grande, 1749-016 Lisboa, Portugal. Electronic address: cristina.ferreira@iniav.pt.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Ferreira
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Biosystems and Integrative Sciences Institute (BioISI), Edificio TecLabs, Campus da FCUL, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Dias
authors.affiliation: Instituto Nacional de Investigação Agrária e Veterinária, I.P. (INIAV, IP), Rua General Morais Sarmento, s/n, 1500-310 Lisboa, Portugal.
authors.forename: Maria Inácia Corrêa
authors.initials: MIC
authors.lastname: de Sá
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Biosystems and Integrative Sciences Institute (BioISI), Edificio TecLabs, Campus da FCUL, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Rogério
authors.initials: R
authors.lastname: Tenreiro
mesh_terms: D041021:Brucella suis / Q000145:classification / Q000235:genetics*; D007446:Chromosome Inversion / Q000235:genetics*; D002874:Chromosome Mapping; D016680:Genome, Bacterial / Q000235:genetics*
keywords: Brucella suis biovar 2; Chromosomal inversion; Optical maps; Strain typing; Whole-genome mapping