Transmission Of Borreua Hermsii, The Agent Of Relapsing Fever, By The Tick Vector Ornithodoros Hermsi

1999 ◽  
Vol 5 (S2) ◽  
pp. 1220-1221
Author(s):  
Elizabeth R. Fischer ◽  
Tom G. Schwan
Keyword(s):  
Salivary Glands ◽  
Soft Tick ◽  
Relapsing Fever ◽  
Tick Feeding ◽  
Infected Tick ◽  
Borrelia Hermsii ◽  
Tick Vector ◽  
Functional Relationships ◽  
Ornithodoros Hermsi ◽  
Tick Midgut

Relapsing fever, a disease characterized by recurrent episodes of high fevers, is caused by geographically distinct spirochetes of the genus Borrelia,transmitted by ticks of the genus Ornithodoros. In the Northwestern United States, the soft tick Ornithodoros hermsi has been identified as the vector for the spirochete Borrelia hermsii. The life cycle of O.hermsi includes larval and multiple nymphal stages prior to full maturation into an adult male or female (Fig.1). Progression into each stage requires a blood-meal typically provided by squirrels and chipmunks, and incidentally humans. Feeding is rapid, lasting 10-60 minutes, and during this time an infected tick can transmit the agent of relapsing fever, B. hermsii. Following ingestion, spirochetes are initially found in the tick midgut. Within 1-3 weeks, they are found in other organs, including the central ganglion and salivary glands. Since saliva is the primary mode of transmission of these bacteria during tick feeding, we assessed by electron microscopy the structural and functional relationships between the spirochetes and the salivary glands.

scholarly journals Cotransmission of Divergent Relapsing Fever Spirochetes by Artificially Infected Ornithodoros hermsi

2011 ◽  
Vol 77 (24) ◽  
pp. 8494-8499 ◽  
Author(s):  
Paul F. Policastro ◽  
Sandra J. Raffel ◽  
Tom G. Schwan
Keyword(s):  
Soft Tick ◽  
Relapsing Fever ◽  
Rodent Host ◽  
Borrelia Hermsii ◽  
Content Type ◽  
Tick Vector ◽  
Tick Infection ◽  
Group I ◽  
Ornithodoros Hermsi ◽  
Feeding Tick

ABSTRACTThe soft tickOrnithodoros hermsi, which ranges in specific arboreal zones of western North America, acts as a vector for the relapsing fever spirocheteBorrelia hermsii. Two genomic groups (genomic group I [GGI] and GGII) ofB. hermsiiare differentiated by multilocus sequence typing yet are codistributed in much of the vector's range. To test whether the tick vector can be infected via immersion, noninfected, colony-derivedO. hermsilarvae were exposed to reduced-humidity conditions before immersion in culture suspensions of several GGI and GGII isolates. We tested for spirochetes in ticks by immunofluorescence microscopy and in mouse blood by quantitative PCR of thevtplocus to differentiate spirochete genotypes. The immersed larval ticks were capable of spirochete transmission to mice at the first nymphal feeding. Tick infection with mixed cultures of isolates DAH (vtp-6) (GGI) and MTW-2 (vtp-5) (GGII) resulted in ticks that caused spirochetemias in mice consisting of MTW-2 or both DAH and MTW-2. These findings show that this soft tick species can acquireB. hermsiiby immersion in spirochete suspensions, that GGI and GGII isolates can coinfect the tick vector by this method, and that these spirochetes can be cotransmitted to a rodent host.

scholarly journals Vector Specificity of the Relapsing Fever Spirochete Borrelia hermsii (Spirochaetales: Borreliaceae) for the Tick Ornithodoros hermsi (Acari: Argasidae) Involves Persistent Infection of the Salivary Glands

2021 ◽  
Author(s):  
Tom G Schwan
Keyword(s):  
Salivary Glands ◽  
Persistent Infection ◽  
Relapsing Fever ◽  
Borrelia Hermsii ◽  
Time Points ◽  
Vector Specificity ◽  
Biochemical Mechanisms ◽  
Tick Vectors ◽  
Vector Competency ◽  
Ornithodoros Hermsi

Abstract The relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae are each maintained and transmitted in nature by their specific tick vectors, Ornithodoros hermsi Wheeler (Acari: Argasidae) and Ornithodoros turicata (Duges), respectively. The basis for this spirochete and vector specificity is not known, but persistent colonization of spirochetes in the tick’s salivary glands is presumed to be essential for transmission by these long-lived ticks that feed in only minutes on their warm-blooded hosts. To examine this hypothesis further, cohorts of O. hermsi and O. turicata were infected with B. hermsii and examined 7–260 d later for infection in their midgut, salivary glands, and synganglion. While the midgut from all ticks of both species at all time points examined were infected with spirochetes, the salivary glands of only O. hermsi remained persistently infected. The salivary glands of O. turicata were susceptible to an early transient infection. However, no spirochetes were observed in these tissues beyond the first 32 d after acquisition. Ticks of both species were fed on mice 112 d after they acquired spirochetes and only those mice fed upon by O. hermsi became infected. Thus, the vector competency for B. hermsii displayed by O. hermsi but not O. turicata lies, in part, in the persistent infection of the salivary glands of the former but not the latter species of tick. The genetic and biochemical mechanisms supporting this spirochete and vector specificity remain to be identified.

scholarly journals Borrelia hermsii Acquisition Order in Superinfected Ticks Determines Transmission Efficiency

2013 ◽  
Vol 81 (8) ◽  
pp. 2899-2908 ◽  
Author(s):  
Paul F. Policastro ◽  
Sandra J. Raffel ◽  
Tom G. Schwan
Keyword(s):  
Dna Sequences ◽  
Transmission Efficiency ◽  
Infection Cycle ◽  
Chromosomal Dna ◽  
Borrelia Hermsii ◽  
Content Type ◽  
Tick Vector ◽  
Acquisition Order ◽  
Host Infection ◽  
Ornithodoros Hermsi

ABSTRACTMultilocus sequence typing ofBorrelia hermsiiisolates reveals its divergence into two major genomic groups (GG), but no differences in transmission efficiency or host pathogenicity are associated with these genotypes. To compare GGI and GGII in the tick-host infection cycle, we first determined if spirochetes from the two groups could superinfect the tick vectorOrnithodoros hermsi. We infected mice with isolates from each group and fed ticks sequentially on these mice. We then fed the infected ticks on naive mice and measured GGI and GGII spirochete densities in vector and host, using quantitative PCR of genotype-specific chromosomal DNA sequences. Sequential feedings resulted in dual tick infections, showing that GGI or GGII primary acquisition did not block superinfection by a secondary agent. On transmission to naive mice at short intervals after acquisition, ticks with primary GGI and secondary GGII spirochete infections caused mixed GGI and GGII infections in mice. However, ticks with primary GGII and secondary GGI spirochete infections caused only GGII infections with all isolate pairs examined. At longer intervals after acquisition, the exclusion of GGI by GGII spirochetes declined and cotransmission predominated. We then examined GGI and GGII spirochetemia in mice following single inoculation and coinoculation by needle and found that GGI spirochete densities were reduced on multiple days when coinoculated with GGII. These findings indicate that dual GGI-GGII spirochete infections can persist in ticks and that transmission to a vertebrate host is dependent on the order of tick acquisition and the interval between acquisition and transmission events.

scholarly journals Imaging of Borrelia turicatae Producing the Green Fluorescent Protein Reveals Persistent Colonization of the Ornithodoros turicata Midgut and Salivary Glands from Nymphal Acquisition through Transmission

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Aparna Krishnavajhala ◽  
Hannah K. Wilder ◽  
William K. Boyle ◽  
Ashish Damania ◽  
Justin A. Thornton ◽  
...  
Keyword(s):  
Life Cycle ◽  
Green Fluorescent Protein ◽  
Salivary Glands ◽  
Fluorescent Protein ◽  
Blood Feeding ◽  
Relapsing Fever ◽  
Tick Feeding ◽  
Content Type ◽  
Green Fluorescent ◽  
Infectious Cycle

ABSTRACT Relapsing fever (RF) spirochetes colonize and are transmitted to mammals primarily by Ornithodoros ticks, and little is known regarding the pathogen's life cycle in the vector. To further understand vector colonization and transmission of RF spirochetes, Borrelia turicatae expressing a green fluorescent protein (GFP) marker (B. turicatae-gfp) was generated. The transformants were evaluated during the tick-mammal infectious cycle, from the third nymphal instar to adult stage. B. turicatae-gfp remained viable for at least 18 months in starved fourth-stage nymphal ticks, and the studies indicated that spirochete populations persistently colonized the tick midgut and salivary glands. Our generation of B. turicatae-gfp also revealed that within the salivary glands, spirochetes are localized in the ducts and lumen of acini, and after tick feeding, the tissues remained populated with spirochetes. The B. turicatae-gfp generated in this study is an important tool to further understand and define the mechanisms of vector colonization and transmission. IMPORTANCE In order to interrupt the infectious cycle of tick-borne relapsing fever spirochetes, it is important to enhance our understanding of vector colonization and transmission. Toward this, we generated a strain of Borrelia turicatae that constitutively produced the green fluorescent protein, and we evaluated fluorescing spirochetes during the entire infectious cycle. We determined that the midgut and salivary glands of Ornithodoros turicata ticks maintain the pathogens throughout the vector's life cycle and remain colonized with the spirochetes for at least 18 months. We also determined that the tick's salivary glands were not depleted after a transmission blood feeding. These findings set the framework to further understand the mechanisms of midgut and salivary gland colonization.

scholarly journals Variable Tick Protein in Two Genomic Groups of the Relapsing Fever Spirochete Borrelia hermsii in Western North America

2005 ◽  
Vol 73 (10) ◽  
pp. 6647-6658 ◽  
Author(s):  
Stephen F. Porcella ◽  
Sandra J. Raffel ◽  
Donald E. Anderson ◽  
Stacey D. Gilk ◽  
James L. Bono ◽  
...  
Keyword(s):  
North America ◽  
Outer Surface ◽  
Surface Protein ◽  
Relapsing Fever ◽  
Gene Encoding ◽  
Borrelia Hermsii ◽  
Tick Vector ◽  
Tick Transmission ◽  
Sequence Relatedness ◽  
Variable Major Proteins

ABSTRACT Borrelia hermsii is the primary cause of tick-borne relapsing fever in North America. When its tick vector, Ornithodoros hermsi, acquires these spirochetes from the blood of an infected mammal, the bacteria switch their outer surface from one of many bloodstream variable major proteins (Vmps) to a unique protein, Vtp (Vsp33). Vtp may be critical for successful tick transmission of B. hermsii; however, the gene encoding this protein has been described previously in only one isolate. Here we identified and sequenced the vtp gene in 31 isolates of B. hermsii collected over 40 years from localities throughout much of its known geographic distribution. Seven major Vtp types were found. Little or no sequence variation existed within types, but between them significant variation was observed, similar to the pattern of diversity described for the outer surface protein C (OspC) gene in Lyme disease spirochetes. The pattern of sequence relatedness among the Vtp types was incongruent in two branches compared to two genomic groups identified among the isolates by multilocus sequence typing of the 16S rRNA, flaB, gyrB, and glpQ genes. Therefore, both horizontal transfer and recombination within and between the two genomic groups were responsible for some of the variation observed in the vtp gene. O. hermsi ticks were capable of transmitting spirochetes in the newly identified genomic group. Therefore, given the longevity of the tick vector and persistent infection of spirochetes in ticks, these arthropods rather than mammals may be the likely host where the exchange of spirochetal DNA occurs.

scholarly journals Acquisition and Subsequent Transmission of Borrelia hermsii by the Soft Tick Ornithodoros hermsi

2011 ◽  
Vol 48 (4) ◽  
pp. 891-895 ◽  
Author(s):  
Job E. Lopez ◽  
Brandi N. McCoy ◽  
Benjamin J. Krajacich ◽  
Tom G. Schwan
Keyword(s):  
Soft Tick ◽  
Borrelia Hermsii ◽  
Ornithodoros Hermsi

scholarly journals The Relapsing Fever Spirochete Borrelia hermsiiContains Multiple, Antigen-Encoding Circular Plasmids That Are Homologous to the cp32 Plasmids of Lyme Disease Spirochetes

2000 ◽  
Vol 68 (7) ◽  
pp. 3900-3908 ◽  
Author(s):  
Brian Stevenson ◽  
Stephen F. Porcella ◽  
Katrina L. Oie ◽  
Cecily A. Fitzpatrick ◽  
Sandra J. Raffel ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Direct Detection ◽  
Human Infection ◽  
Relapsing Fever ◽  
Borrelia Hermsii ◽  
Functional Studies ◽  
Dna Library ◽  
Multiple Antigen ◽  
Antigenic Proteins

ABSTRACT Borrelia hermsii, an agent of tick-borne relapsing fever, was found to contain multiple circular plasmids approximately 30 kb in size. Sequencing of a DNA library constructed from circular plasmid fragments enabled assembly of a composite DNA sequence that is homologous to the cp32 plasmid family of the Lyme disease spirochete,B. burgdorferi. Analysis of another relapsing fever bacterium, B. parkeri, indicated that it contains linear homologs of the B. hermsii and B. burgdorfericp32 plasmids. The B. hermsii cp32 plasmids encode homologs of the B. burgdorferi Mlp and Bdr antigenic proteins and BlyA/BlyB putative hemolysins, but homologs of B. burgdorferi erp genes were absent. Immunoblot analyses demonstrated that relapsing fever patients produced antibodies to Mlp proteins, indicating that those proteins are synthesized by the spirochetes during human infection. Conservation of cp32-encoded genes in differentBorrelia species suggests that their protein products serve functions essential to both relapsing fever and Lyme disease spirochetes. Relapsing fever borreliae replicate to high levels in the blood of infected animals, permitting direct detection and possible functional studies of Mlp, Bdr, BlyA/BlyB, and other cp32-encoded proteins in vivo.

scholarly journals Fibronectin-Binding Protein of Borrelia hermsii Expressed in the Blood of Mice with Relapsing Fever

2014 ◽  
Vol 82 (6) ◽  
pp. 2520-2531 ◽  
Author(s):  
E. R. G. Lewis ◽  
R. A. Marcsisin ◽  
S. A. Campeau Miller ◽  
F. Hue ◽  
A. Phillips ◽  
...  
Keyword(s):  
Binding Protein ◽  
Relapsing Fever ◽  
Borrelia Hermsii ◽  
Fibronectin Binding Protein ◽  
Fibronectin Binding
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