Tick-borne relapsing fever is caused by spirochetes within the genus Borrelia. The hallmark of this disease is recurrent febrile episodes and high spirochete densities in mammalian blood resulting from immune evasion. Between episodes of spirochetemia when bacterial densities are low, it is unknown whether ticks can acquire the spirochetes, become colonized by the bacteria, and subsequently transmit the bacteria once they feed again. We addressed these questions by feeding ticks, Omnithodoros hermsi Wheeler (Acari: Argasidae),daily on an infected mouse during low andhigh levels of spirochete infections. This study demonstrates that spirochete acquisition by the tick vector can occur during low levels of mammalian infection and that once a spirochetemic threshold is attained within the blood, nearly 100% of ticks become colonized by Borrelia hermsii.
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http://dx.doi.org/10.1603/me10283 | DOI Listing |
Appl Microbiol Biotechnol
July 2024
Unité de Génie Enzymatique et Cellulaire (GEC), CNRS UMR 7025, Université de Technologie de Compiègne, Compiègne, 60203, France.
Borrelia, spirochetes transmitted by ticks, are the etiological agents of numerous multisystemic diseases, such as Lyme borreliosis (LB) and tick-borne relapsing fever (TBRF). This study focuses on two surface proteins from two Borrelia subspecies involved in these diseases: CspZ, expressed by Borrelia burgdorferi sensu stricto (also named BbCRASP-2 for complement regulator-acquiring surface protein 2), and the factor H binding A (FhbA), expressed by Borrelia hermsii. Numerous subspecies of Borrelia, including these latter, are able to evade the immune defenses of a variety of potential vertebrate hosts in a number of ways.
View Article and Find Full Text PDFLancet Microbe
May 2024
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China; Department of Epidemiology and Biostatistics, School of Public Health, Wuhan University, Wuhan, China. Electronic address:
Background: The recent discovery of emerging relapsing fever group Borrelia (RFGB) species, such as Borrelia miyamotoi, poses a growing threat to public health. However, the global distribution and associated risk burden of these species remain uncertain. We aimed to map the diversity, distribution, and potential infection risk of RFGB.
View Article and Find Full Text PDFJ Med Entomol
May 2024
Rocky Mountain Veterinary Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA.
Following several days of blood feeding by larval and nymphal ixodid (hard) ticks, the salivary glands degenerate and are completely replaced in the next life stage. Yet, what happens during the molt of immature argasid (soft) ticks after their rapid and small bloodmeal has remained a mystery. Multiple studies of nymphal Ornithodoros hermsi Wheeler (Acari: Argasidae) ticks infected with the relapsing fever spirochete Borrelia hermsii suggested the salivary glands in these ticks may not disintegrate after feeding.
View Article and Find Full Text PDFTicks Tick Borne Dis
May 2024
Bacterial Diseases Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA. Electronic address:
A Borrelia miyamotoi gene with partial homology to bipA of relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae was identified by a GenBank basic alignment search analysis. We hypothesized that this gene product may be an immunogenic antigen as described for other relapsing fever Borrelia (RFB) and could serve as a serological marker for B. miyamotoi infections.
View Article and Find Full Text PDFVector Borne Zoonotic Dis
May 2024
Research Technologies Branch, Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.
The taxonomic status of the relapsing fever spirochete in western North America was established in 1942 and based solely on its specific association with the soft tick vector . Multilocus sequence typing (MLST) of the , , , , and intergenic spacer of isolates collected over many years from various geographic locations and biological sources identified two distinct clades designated previously as Genomic Group I (GGI) and Genomic Group II (GGII). To better assess the taxonomic relationship of these two genomic groups to each other and other species of , DNA sequences of the entire linear chromosome were determined.
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