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Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Molecular Evolution.
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2010 (English)In: BMC Genomics, ISSN 1471-2164, Vol. 11, 152- p.Article in journal (Refereed) Published
Abstract [en]

Background: Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of Bartonella grahamii, one of the most prevalent blood-borne bacteria in wild rodents, revealed a higher abundance of genes for host-cell interaction systems than in the genomes of closely related human pathogens. The sequence variability within the global B. grahamii population was recently investigated by multi locus sequence typing, but no study on the variability of putative host-cell interaction systems has been performed.

Results: To study the population dynamics of B. grahamii, we analyzed the genomic diversity on a whole-genome scale of 27 B. grahamii strains isolated from four different species of wild rodents in three geographic locations separated by less than 30 km. Even using highly variable spacer regions, only 3 sequence types were identified. This low sequence diversity contrasted with a high variability in genome content. Microarray comparative genome hybridizations identified genes for outer surface proteins, including a repeated region containing the fha gene for filamentous hemaggluttinin and a plasmid that encodes a type IV secretion system, as the most variable. The estimated generation times in liquid culture medium for a subset of strains ranged from 5 to 22 hours, but did not correlate with sequence type or presence/absence patterns of the fha gene or the plasmid.

Conclusion: Our study has revealed a geographic microstructure of B. grahamii in wild rodents. Despite near-identity in nucleotide sequence, major differences were observed in gene presence/absence patterns that did not segregate with host species. This suggests that genetically similar strains can infect a range of different hosts.

Place, publisher, year, edition, pages
2010. Vol. 11, 152- p.
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-108379DOI: 10.1186/1471-2164-11-152ISI: 000276363100003OAI: oai:DiVA.org:uu-108379DiVA: diva2:236439
Available from: 2009-09-23 Created: 2009-09-17 Last updated: 2011-01-05Bibliographically approved
In thesis
1. Genome Evolution and Host Adaptation in Bartonella
Open this publication in new window or tab >>Genome Evolution and Host Adaptation in Bartonella
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Bacteria of the genus Bartonella infect the red blood cells of a wide range of wild and domestic mammals and are transmitted between hosts by blood-sucking insects. Although most Bartonella infections are asymptomatic, the genus contains several human pathogens. In this work, host adaptation and host switches in Bartonella have been studied from a genomic perspective, with special focus on the acquisition and evolution of genes involved in host interactions.

As part of this study, the complete genome of B. grahamii isolated from a Swedish wood mouse was sequenced. A genus-wide comparison revealed that rodent-associated Bartonella species, which have rarely been associated with human disease, have the largest genomes and the largest number of host-adaptability genes. Analysis of known and putative genes for host interactions identified several families of autotransporters as horizontally transferred to the Bartonella ancestor, with a possible role both during early host adaptation and subsequent host shifts.

In B. grahamii, the association of a gene transfer agent (GTA) and phage-derived run-off replication of a large genomic segment was demonstrated for the first time. Among all acquisitions to the Bartonella ancestor, the only well conserved gene clusters are those that encode the GTA and contain the origin of the run-off replication. This conservation, along with a high density of host-adaptability genes in the amplified region suggest that the GTA provides a strong selective advantage, possibly by increasing recombination frequencies of host-adaptability genes, thereby facilitating evasion of the host immune system and colonization of new hosts.

B. grahamii displays stronger geographic pattern and higher recombination frequencies than the cat-associated B. henselae, probably caused by different lifestyles and/or population sizes of the hosts. The genomic diversity of B. grahamii is markedly lower in Europe and North America than in Asia, possibly an effect of reduced host variability in these areas following the latest ice age.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 675
Bartonella, genome evolution, genome diversity, phage, gene transfer agent, secretion system, microarray
National Category
Bioinformatics and Systems Biology
Research subject
Evolutionary Genetics
urn:nbn:se:uu:diva-108376 (URN)978-91-554-7616-8 (ISBN)
Public defence
2009-11-06, Lindahlsalen, EBC, Norbyvägen 18, Uppsala, 09:15 (English)
Available from: 2009-10-15 Created: 2009-09-17 Last updated: 2009-10-15Bibliographically approved

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