Evidence for frequent OspC gene transfer between Borrelia valaisiana sp. nov. and other Lyme disease spirochetes

Wang, G

doi:10.1016/s0378-1097(99)00346-8

Cited by 16 publications

(20 citation statements)

References 17 publications

(36 reference statements)

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“…The data presented here are in agreement with those from the earlier studies and support the clonality of B. burgdorferi. Several groups have reported evidence for lateral exchange of plasmid-encoded genes in B. burgdorferi (11,12,22). The mechanisms for such gene transfer are not known, but the present data suggest that it does not occur via exchange of entire plasmids between isolates.…”

contrasting

confidence: 46%

Characterization of Borrelia burgdorferi Isolated from Erythema Migrans Lesions: Interrelationship of Three Molecular Typing Methods

Iyer¹,

Liveris²,

Adams³

et al. 2001

J Clin Microbiol

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Genetic diversity among Borrelia burgdorferi isolates recovered from the skin of Lyme disease patients was assessed by ribosomal DNA (rDNA) spacer restriction fragment length polymorphism analysis, genomic restriction site polymorphism analysis, and plasmid content analysis. There was a significant association between the three rDNA spacer types, the six pulsed-field gel types, and plasmid content (P < 0.001). The association between distinct chromosomal and plasmid markers implies a clonal origin for each genotype.Lyme disease, a disorder which may affect multiple organ systems, results from infection with the spirochete Borrelia burgdorferi. Between 1989 and 1997, 114,314 cases of Lyme disease were reported to the Centers for Disease Control and Prevention, making Lyme disease the most common vectorborne disease in the United States (16,21). Early Lyme disease is manifested by a characteristic skin rash, erythema migrans (EM), and is frequently accompanied by systemic symptoms (14, 15). Molecular analysis of B. burgdorferi isolates has resulted in the differentiation of B. burgdorferi sensu lato into 10 distinct species (23). B. burgdorferi sensu stricto is the only known Lyme disease borrelia infecting patients in North America. Significant genetic heterogeneity among B. burgdorferi sensu stricto isolates in North America has been reported (1,6,8,13). The type strain of B. burgdorferi sensu stricto, B31 has a large linear genome of 910,725 bp and 21 linear and circular plasmids with a total size of 610,694 bp (3, 7).It has long been recognized that the clinical expression of B. burgdorferi infection is diverse (15). Possible explanations for this variability are differences in the genotypes of the infecting strain of B. burgdorferi. We developed a typing method based on restriction fragment length polymorphism (RFLP) in the 16S-23S ribosomal DNA (rDNA) spacer of B. burgdorferi and used it to analyze clinical isolates obtained from early Lyme disease patients (9). A highly significant association was found between the infecting RFLP type in the skin and the presence of spirochetemia or multiple EM lesions (25), suggesting that differences in the clinical presentations of Lyme disease patients may, indeed, be related to B. burgdorferi genotype. rDNA spacer analysis provides genetic typing information for a single genomic locus and interrogates a chromosomal region which is unlikely to have a direct role in pathogenesis. In order to obtain additional, broader typing information, 48 cutaneous isolates from early Lyme disease patients were analyzed by pulsed-field gel electrophoresis (PFGE).Subjects, skin biopsy, and cultivation. All subjects were adults with EM enrolled in a prospective study at the Lyme Disease Diagnostic Center of the Westchester Medical Center, Valhalla, N.Y. Skin biopsy specimens (2 mm) were obtained from the leading edge of primary EM lesions and cultured in BSK-II medium as described previously (19).PFGE. Spirochetes were harvested by centrifugation and washed twice with sterile phosphate-b...

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confidence: 46%

Characterization of Borrelia burgdorferi Isolated from Erythema Migrans Lesions: Interrelationship of Three Molecular Typing Methods

Iyer¹,

Liveris²,

Adams³

et al. 2001

J Clin Microbiol

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“…Nucleotide polymorphisms are retained at surface-antigen loci like ospC by positive natural selection (Wang et al 1999a;Barbour and Travinsky 2010). More directly, we found at least three independent gene-conversion events at the guaA-ospC-bbb22 loci in a single B. burgdorferi s.s. genome ( Figure S4).…”

Section: Discussionmentioning

confidence: 59%

Pervasive Recombination and Sympatric Genome Diversification Driven by Frequency-Dependent Selection in Borrelia burgdorferi, the Lyme Disease Bacterium

Vargas²,

et al. 2011

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How genomic diversity within bacterial populations originates and is maintained in the presence of frequent recombination is a central problem in understanding bacterial evolution. Natural populations of Borrelia burgdorferi, the bacterial agent of Lyme disease, consist of diverse genomic groups co-infecting single individual vertebrate hosts and tick vectors. To understand mechanisms of sympatric genome differentiation in B. burgdorferi, we sequenced and compared 23 genomes representing major genomic groups in North America and Europe. Linkage analysis of .13,500 single-nucleotide polymorphisms revealed pervasive horizontal DNA exchanges. Although three times more frequent than point mutation, recombination is localized and weakly affects genome-wide linkage disequilibrium. We show by computer simulations that, while enhancing population fitness, recombination constrains neutral and adaptive divergence among sympatric genomes through periodic selective sweeps. In contrast, simulations of frequency-dependent selection with recombination produced the observed pattern of a large number of sympatric genomic groups associated with major sequence variations at the selected locus. We conclude that negative frequency-dependent selection targeting a small number of surface-antigen loci (ospC in particular) sufficiently explains the maintenance of sympatric genome diversity in B. burgdorferi without adaptive divergence. We suggest that pervasive recombination makes it less likely for local B. burgdorferi genomic groups to achieve host specialization. B. burgdorferi genomic groups in the northeastern United States are thus best viewed as constituting a single bacterial species, whose generalist nature is a key to its rapid spread and human virulence. G ENETIC discontinuity, the basis of biodiversity, is ubiquitous in prokaryotes as well as in eukaryotes. Most bacterial populations display a highly clonal genetic structure, in which the observable number of multilocus genotypes is far fewer than the number expected under the assumption of free recombination (Maynard Smith et al. 1993). Bacterial clonality was originally thought of as a result of a lack or rarity of recombination among asexually reproducing and independently evolving clones (Ochman and Selander 1984). Since then, molecular surveys of natural bacterial populations using protein electrophoresis, multilocus sequencing typing (MLST), and whole-genome PRJNA3, PRJNA28633, PRJNA19839, PRJNA29359, PRJNA28629, PRJNA29357, PRJNA21003, PRJNA19835, PRJNA28627, PRJNA21001, PRJNA29361, PRJNA28621, PRJNA19837, PRJNA20999, PRJNA28631, PRJNA29363, PRJNA17057, PRJNA19841, PRJNA12554, PRJNA28625, PRJNA29573, PRJNA19843, and PRJNA28635. 1 Present address: Odum School of Ecology, University of Georgia, Athens, GA 30602. sequencing revealed that horizontal genetic exchange is in fact often more frequent than point mutations in bacteria, including species known as strongly clonal (Maynard Smith et al. 1993;Feil and Spratt 2001;Didelot and Maiden 2010;Retc...

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“…This was confirmed for B. lusitaniae in North Africa. The genetic variability of the ospC gene of pathogenic B. burgdorferi sensu lato strains has been extensively studied (14,21,37,39). The diversity of the ospC gene is mostly acquired by lateral transfer between species or within species.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Borrelia lusitaniae Isolates Collected in Tunisia and Morocco

et al. 2005

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Borrelia lusitaniae is a species within the complex Borrelia burgdorferi sensu lato and is infrequently isolated in Europe. In contrast, this species is by far the most predominant in North Africa and in Portugal. In this study, we analyzed the genetic diversity, at several loci, of a large population of isolates from free-living Ixodes ricinus ticks collected in Tunisia and Morocco. We found a moderate diversity of the whole genome by using pulsed-field gel electrophoresis as well as in the ospA gene sequences, compared to a high level of strain homogeneity in the small noncoding ribosomal spacer. In contrast, a high diversity of this locus has been previously reported for Portuguese isolates. We hypothesize that B. lusitaniae strains isolated in North Africa constitute a clone of Portuguese origin.Within the complex Borrelia burgdorferi sensu lato, three species, B. burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii, are known to cause a broad spectrum of human manifestations that are described as Lyme borreliosis. The genetic diversity of pathogenic species has been largely investigated both at the species level and at the strain level within each species (41). Otherwise, although its pathogenicity for humans is only suspected (31, 33), Borrelia valaisiana represents a widely distributed species in ticks throughout Europe and Asia and therefore has been extensively studied (12,22,32,38,40).In contrast to these species, little data are available concerning Borrelia lusitaniae. Only sporadic isolates have been characterized from ticks collected in the Czech Republic, Moldavia, Ukraine, and Belarus (20), in Slovakia (11), in Spain (3), in Poland (25), in France (30), in Switzerland (15-17), or in Turkey (13), and these isolates did not show any significant diversity. However, a study conducted in Portugal revealed a large diversity among B. lusitaniae strains isolated from a local tick population (6). Moreover, it is noteworthy that, among the three first Portuguese isolates identified as B. lusitaniae, two different types were demonstrated (20,26). Hence, these studies suggested a higher diversity among B. lusitaniae around the Mediterranean basin. However, all these studies only focused on the small ribosomal rrf-rrl spacer and, therefore, the global diversity of this species remained unknown.Recently, we reported that B. lusitaniae was, by far, the most prevalent species, ranging from 96.6 to 100% of the B. burgdorferi sensu lato species identified in Tunisia and Morocco (35,44,46). The report of some Lyme borreliosis cases in North Africa (1, 27) and the recent isolation in Portugal of B.lusitaniae from the skin of a human patient with chronic lesions (5) prompted us to characterize this species as a potential human pathogen. Therefore, we investigated the molecular characterization and the genetic diversity of B. lusitaniae isolated from free-living Ixodes ricinus ticks in Tunisia and Morocco. For these purposes we studied two single loci (ospC and ospA) and the noncoding intergenic spacer (r...

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Evidence for frequent OspC gene transfer between Borrelia valaisiana sp. nov. and other Lyme disease spirochetes

Cited by 16 publications

References 17 publications

Characterization of Borrelia burgdorferi Isolated from Erythema Migrans Lesions: Interrelationship of Three Molecular Typing Methods

Characterization of Borrelia burgdorferi Isolated from Erythema Migrans Lesions: Interrelationship of Three Molecular Typing Methods

Pervasive Recombination and Sympatric Genome Diversification Driven by Frequency-Dependent Selection in Borrelia burgdorferi, the Lyme Disease Bacterium

Characterization of Borrelia lusitaniae Isolates Collected in Tunisia and Morocco

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