Dataset Information

Molecular Epidemiology of Novel Pathogen "Brachyspira hampsonii" Reveals Relationships between Diverse Genetic Groups, Regions, Host Species, and Other Pathogenic and Commensal Brachyspira Species.

ABSTRACT: Outbreaks of bloody diarrhea in swine herds in the late 2000s signaled the reemergence of an economically significant disease, swine dysentery, in the United States. Investigations confirmed the emergence of a novel spirochete in swine, provisionally designated "Brachyspira hampsonii," with two genetically distinct clades. Although it has since been detected in swine and migratory birds in Europe and North America, little is known about its genetic diversity or its relationships with other Brachyspira species. This study characterizes B. hampsonii using a newly developed multilocus sequence typing (MLST) approach and elucidates the diversity, distribution, population structure, and genetic relationships of this pathogen from diverse epidemiological sources globally. Genetic characterization of 81 B. hampsonii isolates, originating from six countries, with our newly established MLST scheme identified a total of 20 sequence types (STs) belonging to three clonal complexes (CCs). B. hampsonii showed a heterogeneous population structure with evidence of microevolution locally in swine production systems, while its clustering patterns showed associations with its epidemiological origins (country, swine production system, and host species). The close genetic relatedness of B. hampsonii isolates from different countries and host species highlights the importance of strict biosecurity control measures. A comparative analysis of 430 isolates representing seven Brachyspira species (pathogens and commensals) from 19 countries and 10 host species depicted clustering by microbial species. It revealed the close genetic relatedness of B. hampsonii with commensal Brachyspira species and also provided support for the two clades of B. hampsonii to be considered a single species.

SUBMITTER: Mirajkar NS

PROVIDER: S-EPMC4540906 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Molecular Epidemiology of Novel Pathogen "Brachyspira hampsonii" Reveals Relationships between Diverse Genetic Groups, Regions, Host Species, and Other Pathogenic and Commensal Brachyspira Species.

Mirajkar Nandita S NS Bekele Aschalew Z AZ Chander Yogesh Y YY Gebhart Connie J CJ

Journal of clinical microbiology 20150701 9

Outbreaks of bloody diarrhea in swine herds in the late 2000s signaled the reemergence of an economically significant disease, swine dysentery, in the United States. Investigations confirmed the emergence of a novel spirochete in swine, provisionally designated "Brachyspira hampsonii," with two genetically distinct clades. Although it has since been detected in swine and migratory birds in Europe and North America, little is known about its genetic diversity or its relationships with other Brach ...[more]

PMID: 26135863

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Project description:BackgroundBrachyspira pilosicoli is an anaerobic spirochaete that can colonizes the large intestine of many host species. Infection is particularly problematic in pigs and adult poultry, causing colitis and diarrhea, but it is also known to result in clinical problems in human beings. Despite the economic importance of the spirochaete as an animal pathogen, and its potential as a zoonotic agent, it has not received extensive study.MethodsA multilocus sequence typing (MLST) method based on the scheme used for other Brachyspira species was applied to 131 B. pilosicoli isolates originating from different host species and geographical areas. A variety of phylogenetic trees were constructed and analyzed to help understand the data.ResultsThe isolates were highly diverse, with 127 sequence types and 123 amino acid types being identified. Large numbers (50-112) of alleles were present at each locus, with all loci being highly polymorphic. The results of Shimodaira-Hasegawa tests identified extensive genetic recombination, although the calculated standardized index of association value (0.1568; P <0.0005) suggested the existence of some clonality. Strains from different host species and geographical origins generally were widely distributed throughout the population, although in nine of the ten cases where small clusters of related isolates occurred these were from the same geographical areas or farms/communities, and from the same species of origin. An exception to the latter was a cluster of Australian isolates originating from pigs, chickens and a human being, suggesting the likelihood of relatively recent transmission of members of this clonal group between species.ConclusionsThe strongly recombinant population structure of B. pilosicoli contrasts to the more highly clonal population structures of the related species Brachyspira hyodysenteriae and Brachyspira intermedia, both of which are specialized enteric pathogens of pigs and poultry. The genomic plasticity of B. pilosicoli may help to explain why it has been able to adapt to colonize the large intestines of a wider range of hosts compared to other Brachyspira species. The identification of a clonal group of isolates that had been recovered from different host species, including a human being, suggests that zoonotic transmission by B. pilosicoli may occur in nature. Evidence for local transmission between the same host species also was obtained.

Dataset Information

Molecular Epidemiology of Novel Pathogen "Brachyspira hampsonii" Reveals Relationships between Diverse Genetic Groups, Regions, Host Species, and Other Pathogenic and Commensal Brachyspira Species.

Publications

Molecular Epidemiology of Novel Pathogen "Brachyspira hampsonii" Reveals Relationships between Diverse Genetic Groups, Regions, Host Species, and Other Pathogenic and Commensal Brachyspira Species.

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