Emerging diversity and ongoing expansion of the genus Brucella

Whatmore, Adrian M.; Foster, Jeffrey T.

doi:10.1016/j.meegid.2021.104865

Cited by 52 publications

(61 citation statements)

References 174 publications

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“…The genus Brucella ( https://lpsn.dsmz.de/genus/brucella ) includes facultative intracellular Gram-negative bacterial pathogens that differ, among other phenotypic and genotypic characteristics, in pathogenicity and host preference ( 1 , 2 ). Depending on the Brucella species, a variety of terrestrial and marine mammal species can be infected, but amphibians, reptiles, and fish have also been reported as hosts for the atypical Brucella strains described in the recent years ( 1 , 2 ). Ovine brucellosis is mainly caused by Brucella melitensis and Brucella ovis , species that share high levels of homology at the DNA level ( 3 ) but exhibit relevant differences regarding pathogenicity.…”

Section: Introductionmentioning

confidence: 99%

The Transcriptional Regulator MucR, but Not Its Controlled Acid-Activated Chaperone HdeA, Is Essential for Virulence and Modulates Surface Architecture and Properties in Brucella ovis PA

2022

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Brucella ovis is a non-zoonotic bacterium causing contagious epididymitis and other genital lesions in rams and responsible for significant economic losses in sheep-breeding areas. It is a naturally rough (without O-chains in the lipopolysaccharide) Brucella species whose virulence mechanisms have been less explored than those of zoonotic smooth brucellae (bearing O-chains that mask other outer membrane molecules). Considering the rough nature of Brucella ovis, the influence of surface components other than O-chains on its biological properties may be greater than in smooth Brucella species. Here we describe the construction and characterization of the mucR deletion mutant of virulent B. ovis PA, which is defective in a transcriptional regulator, affecting surface properties and virulence in smooth brucellae. This mutant showed increased amounts of three proteins identified as HdeA (acid-activated chaperone), Omp25d (outer membrane protein undetectable in the parental strain), and BOV_A0299 (hypothetical protein of unknown function). This observation correlated with the enhanced transcription of the corresponding genes and constitutes the first report on this type of proteome alteration in Brucella ΔmucR mutants. The upstream regions of the three genes contained AT rich domains with T-A steps described as binding sites for MucR in the Brucella abortus 2308 babR promoter (gene also upregulated in B. ovis ΔmucR), which suggests that hdeA, omp25d, and BOV_A0299 expression could be repressed by MucR through a direct binding to their promoter regions. Relative quantification of transcripts of several other genes selected according to the transcriptome of smooth brucellae ΔmucR mutants revealed not only similarities but also relevant differences among strains, such as those detected in flagellar and virB genes. Periplasmic HdeA has been related to the resistance of B. abortus to acidic pH, conditions encountered by Brucella inside phagocytes, but the deletion of hdeA in B. ovis PA and the ΔmucR mutant did not modify any of the evaluated properties of these strains. The B. ovis PA ΔmucR and ΔmucRΔhdeA mutants had defective in vitro growth and altered surface properties and architecture, exemplified by detectable amounts of Omp25d. Moreover, they showed virulence attenuation but established persistent splenic infection in mice, which encourages their evaluation as specifical attenuated vaccines against B. ovis.

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Section: Introductionmentioning

confidence: 99%

The Transcriptional Regulator MucR, but Not Its Controlled Acid-Activated Chaperone HdeA, Is Essential for Virulence and Modulates Surface Architecture and Properties in Brucella ovis PA

2022

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“…This phylogenetic tree highlighted that all Brucella species were clearly separated into different clusters, i.e., each species can be defined by specific branches, thus providing a speciesspecific panel of SNPs. This phylogenetic tree was rooted with the clade of 'atypical' Brucella strains (including B. inopinata and strains isolated in bullfrogs) and as expected, Brucella species were split into two groups: the first one regrouping 'classical species' and the second group containing 'atypical' or early-diverging Brucella strains [5,45]. The most basal strain from the classical species was B. microti CCM 4915, whereas other lineages radiated quickly, indicating that all species diverged almost simultaneously, as previously reported [5,45].…”

Section: Snp-based Phylogeny Of the Brucella Genusmentioning

confidence: 80%

“…The matrix of filtered SNPs is used to generate a phylogenetic tree, using a maximum-likelihood approach (BioNumerics 7.6.2 and MEGA X), allowing phylogenetic analyses. The tree was rooted using strains of 'atypical' Brucella, as in a recent study [5]. Based on this phylogenetic tree, fixed variants specific to species and biovars are extracted and are used to develop the HRM-PCR assay.…”

Section: Wgsnp Analysesmentioning

confidence: 99%

“…Brucellae are a group of facultative intracellular Alphaproteobacteria that usually infect domesticated animals and humans, but also wildlife [1][2][3][4]. To date, the genus is composed of 12 species [5], mostly characterized by phenotypical and biochemical preferences: the six classical species B. abortus (bovine), B. melitensis (caprine and ovine), B. suis (porcine), B. canis (canine), B. ovis (ovine), B. neotomae (desert woodrat) [4,[6][7][8], and six new species B. ceti (dolphins, porpoises and whales) [9], B. pinnipedialis (seals) [9], B. microti (common vole, frogs, wild boar) [10][11][12][13], B. inopinata (natural host not clearly identified, incidental association with breast implant) [14], B. papionis (baboon) [15] and B. vulpis [16]. The genus is therefore in constant evolution and new and atypical hosts are regularly identified, such as Brucella isolated in frogs [17,18] or more recently Brucella DNA detected in bats [19].…”

Section: Introductionmentioning

confidence: 99%

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High-Resolution Melting PCR as Rapid Genotyping Tool for Brucella Species

et al. 2022

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Brucella sp. are the causative agents of brucellosis. One of the main characteristics of the Brucella genus concerns its very high genetic homogeneity. To date, classical bacteriology typing is still considered as the gold standard assay for direct diagnosis of Brucella. Molecular approaches are routinely used for the identification of Brucella at the genus level. However, genotyping is more complex, and to date, no method exists to quickly assign a strain into species and biovar levels, and new approaches are required. Next generation sequencing (NGS) opened a new era into the diagnosis of bacterial diseases. In this study, we designed a high-resolution melting (HRM) method for the rapid screening of DNA and direct assignment into one of the 12 species of the Brucella genus. This method is based on 17 relevant single nucleotide polymorphisms (SNPs), identified and selected from a whole genome SNP (wgSNP) analysis based on 988 genomes (complete and drafts). These markers were tested against the collection of the European Reference Laboratory (EU-RL) for brucellosis (1440 DNAs extracted from Brucella strains). The results confirmed the reliability of the panel of 17 SNP markers, allowing the differentiation of each species of Brucella together with biovars 1, 2, and 3 of B. suis and vaccine strain Rev1 (B. melitensis) within 3 h, which is a considerable gain of time for brucellosis diagnosis. Therefore, this genotyping tool provides a new and quick alternative for Brucella identification based on SNPs with the HRM-PCR assay.

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“…An emerging theme of recent years has been the recognition of new groups of strains expanding known ecological niches and genetic diversity of the genus Brucella (Moreno, 2020 ; Whatmore and Foster, 2021 ). Guzmán-Verri et al characterized a novel Brucella sp.…”

Section: Novel Brucella Species and Strainsmentioning

confidence: 99%