Diversity and Distribution of<i>Borrelia hermsii</i>

Schwan, Tom G.; Raffel, Sandra J.; Schrumpf, Merry E.; Porcella, Stephen F.

doi:10.3201/eid1303.060958

Cited by 70 publications

(95 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although Arizona has a history of TBRF infection, this is the first report of IGS sequence variants from the region. 12,13 The B. hermsii IGS sequences from this study were most similar to B. hermsii IGS GGI and within that group, closest to strain SB82 (GGI, Type 2) that was isolated from a human patient in Colorado. 12 In other western states, chipmunks (Tamias spp.)…”

Section: Discussionmentioning

confidence: 92%

Tick-Borne Relapsing Fever Outbreak Among a High School Football Team at an Outdoor Education Camping Trip, Arizona, 2014

Jones¹,

Hranac²,

Schumacher

et al. 2016

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

Abstract. During August 2014, five high school students who had attended an outdoor education camp were hospitalized with a febrile illness, prompting further investigation. Ten total cases of tick-borne relapsing fever (TBRF) were identified-six cases confirmed by culture or visualization of spirochetes on blood smear and four probable cases with compatible symptoms (attack rate: 23%). All patients had slept in the campsite's only cabin. Before the camp, a professional pest control company had rodent proofed the cabin, but no acaricides had been applied. Cabin inspection after the camp found rodents and Ornithodoros ticks, the vector of TBRF. Blood samples from a chipmunk trapped near the cabin and from patients contained Borrelia hermsii with identical gene sequences (100% over 630 base pairs). Health departments in TBRF endemic areas should consider educating cabin owners and pest control companies to apply acaricides during or following rodent proofing, because ticks that lack rodents for a blood meal might feed on humans.

show abstract

Section: Discussionmentioning

confidence: 92%

Tick-Borne Relapsing Fever Outbreak Among a High School Football Team at an Outdoor Education Camping Trip, Arizona, 2014

Jones¹,

Hranac²,

Schumacher

et al. 2016

The American Journal of Tropical Medicine and Hygiene

View full text Add to dashboard Cite

show abstract

“…(i) B. duttonii is present in sub-Saharan Africa and transmitted by the soft-body tick Ornithodoros moubata moubata; this species likely causes more RF cases than anywhere else in the world (38). (ii) B. hermsii is the most common RF-causing pathogen in North America; it is transmitted by the tick Ornithodoros hermsi (31,62) and has been the focus of antigenic variation research (5,68). (iii) B. recurrentis occurs endemically in the highlands of Ethiopia, with sporadic cases in Sudan, and is transmitted by the human body louse Pediculus humanus humanus (20).…”

mentioning

confidence: 99%

Oms38 Is the First Identified Pore-Forming Protein in the Outer Membrane of Relapsing Fever Spirochetes

et al. 2008

Self Cite

View full text Add to dashboard Cite

Relapsing fever is a worldwide, endemic disease caused by several spirochetal species belonging to the genus Borrelia. During the recurring fever peaks, borreliae proliferate remarkably quickly compared to the slow dissemination of Lyme disease Borrelia and therefore require efficient nutrient uptake from the blood of their hosts. This study describes the identification and characterization of the first relapsing fever porin, which is present in the outer membranes of B. duttonii, B. hermsii, B. recurrentis, and B. turicatae. The pore-forming protein was purified by hydroxyapatite chromatography and designated Oms38, for outer membrane-spanning protein of 38 kDa. Biophysical characterization of Oms38 was done by using the black lipid bilayer method, demonstrating that Oms38 forms small, water-filled channels of 80 pS in 1 M KCl that did not exhibit voltage-dependent closure. The Oms38 channel is slightly selective for anions and shows a ratio of permeability for cations over anions of 0.41 in KCl. Analysis of the deduced amino acid sequences demonstrated that Oms38 contains an N-terminal signal sequence which is processed under in vivo conditions. Oms38 is highly conserved within the four studied relapsing fever species, sharing an overall amino acid identity of 58% and with a strong indication for the presence of amphipathic ␤-sheets.

show abstract

“…B. hermsii strain YOR is a well-characterized genomic group II isolate (9,18,26). B. hermsii YOR and all derivative strains were cultivated in Barbour-Stoenner-Kelly (BSK)-H complete medium supplemented with 12% rabbit serum (37°C; 5% CO 2 ) in sealed bottles.…”

Section: Methodsmentioning

confidence: 99%

“…In the Americas, TBRF occurs most commonly as outbreaks. Cases in the United States cluster in high-elevation, coniferous forests of the West where the primary etiological agents are Borrelia hermsii and Borrelia turicatae (6)(7)(8)(9)(10). TBRF manifests with recurring episodes of high fever that coincide with the emergence of high-density (10 4 to 10 8 spirochetes ml Ϫ1 blood), antigenically distinct populations of spirochetes (11).…”

mentioning

confidence: 99%

The Borrelia hermsii Factor H Binding Protein FhbA Is Not Required for Infectivity in Mice or for Resistance to Human Complement In Vitro

et al. 2014

View full text Add to dashboard Cite

The primary causative agent of tick-borne relapsing fever in North America is Borrelia hermsii. It has been hypothesized that B. hermsii evades complement-mediated destruction by binding factor H (FH), a host-derived negative regulator of complement. In vitro, B. hermsii produces a single FH binding protein designated FhbA (FH binding protein A). The properties and ligand binding activity of FhbA suggest that it plays multiple roles in pathogenesis. It binds plasminogen and has been identified as a significant target of a B1b B cell-mediated IgM response in mice. FhbA has also been explored as a potential diagnostic antigen for B. hermsii infection in humans. The ability to test the hypothesis that FhbA is a critical virulence factor in vivo has been hampered by the lack of well-developed systems for the genetic manipulation of the relapsing fever spirochetes. In this report, we have successfully generated a B. hermsii fhbA deletion mutant (the B. hermsii YOR⌬fhbA strain) through allelic exchange mutagenesis. Deletion of fhbA abolished FH binding by the YOR⌬fhbA strain and eliminated cleavage of C3b on the cell surface. However, the YOR⌬fhbA strain remained infectious in mice and retained resistance to killing in vitro by human complement. Collectively, these results indicate that B. hermsii employs an FhbA/FH-independent mechanism of complement evasion that allows for resistance to killing by human complement and persistence in mice.

show abstract

Diversity and Distribution ofBorrelia hermsii

Cited by 70 publications

References 24 publications

Tick-Borne Relapsing Fever Outbreak Among a High School Football Team at an Outdoor Education Camping Trip, Arizona, 2014

Tick-Borne Relapsing Fever Outbreak Among a High School Football Team at an Outdoor Education Camping Trip, Arizona, 2014

Oms38 Is the First Identified Pore-Forming Protein in the Outer Membrane of Relapsing Fever Spirochetes

The Borrelia hermsii Factor H Binding Protein FhbA Is Not Required for Infectivity in Mice or for Resistance to Human Complement In Vitro

Contact Info

Product

Resources

About