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Parasites & Vectors Feb 2020Ixodes ricinus is the most common tick species in Europe and the main vector for Borrelia burgdorferi (sensu lato) and tick-borne encephalitis virus (TBEV). It is...
BACKGROUND
Ixodes ricinus is the most common tick species in Europe and the main vector for Borrelia burgdorferi (sensu lato) and tick-borne encephalitis virus (TBEV). It is involved also in the transmission of Borrelia miyamotoi, a relapsing fever spirochete that causes health disorders in humans. Little is known regarding the circulation of Borrelia species and the natural foci of TBEV in north-eastern Germany. The goal of this study was to investigate the infection rates of Borrelia spp. and of TBEV in I. ricinus ticks from north-eastern Germany.
METHODS
Ticks were collected by flagging from 14 forest sites in Mecklenburg-Western Pomerania between April and October 2018. RNA and DNA extraction was performed from individual adult ticks and from pools of 2-10 nymphs. Real time reverse transcription PCR (RT-qPCR) targeted the 3' non-coding region of TBEV, while DNA of Borrelia spp. was tested by nested PCR for the amplification of 16S-23S intergenic spacer. Multilocus sequence typing (MLST) was performed on B. miyamotoi isolates.
RESULTS
In total, 2407 ticks were collected (239 females, 232 males and 1936 nymphs). Female and male I. ricinus ticks had identical infection rates (both 12.1%) for Borrelia spp., while nymphal pools showed a minimum infection rate (MIR) of 3.3%. Sequencing revealed four Borrelia species: B. afzelii, B. garinii, B. valaisiana and B. miyamotoi. Borrelia afzelii had the highest prevalence in adult ticks (5.5%) and nymphs (MIR of 1.8%). Borrelia miyamotoi was identified in 3.0% of adults and registered the MIR of 0.8% in nymphs. Borrelia valaisiana was confirmed in 2.5% adult ticks and nymphs had the MIR of 0.7%, while B. garinii was present in 1.1% of adults and showed a MIR of 0.1% in nymphs. The MLST of B. miyamotoi isolates showed that they belong to sequence type 635. No tick sample was positive after RT-qPCR for TBEV RNA.
CONCLUSIONS
The prevalence of B. miyamotoi in I. ricinus ticks registered similar levels to other reports from Europe suggesting that this agent might be well established in the local tick population. The detection of B. burgdorferi (s.l.) indicates a constant circulation in tick populations from this region.
Topics: Animals; Borrelia; Borrelia burgdorferi; Encephalitis Viruses, Tick-Borne; Female; Forests; Germany; Ixodes; Male; Multilocus Sequence Typing; Nymph; Real-Time Polymerase Chain Reaction; Ticks
PubMed: 32106890
DOI: 10.1186/s13071-020-3969-7 -
PLoS Pathogens Mar 2022Borrelia species are amino acid auxotrophs that utilize di- and tri- peptides obtained through their oligopeptide transport system to supply amino acids for replicative...
Borrelia species are amino acid auxotrophs that utilize di- and tri- peptides obtained through their oligopeptide transport system to supply amino acids for replicative growth during their enzootic cycles. However, Borrelia species from both the Lyme disease (LD) and relapsing fever (RF) groups harbor an amino acid transport and catabolism system, the Arginine Deiminase System (ADI), that could potentially augment intracellular L-arginine required for growth. RF spirochetes contain a "complete", four gene ADI (arcA, B, D, and C) while LD spirochetes harbor arcA, B, and sometimes D but lack arcC (encoding carbamate kinase). In this study, we evaluated the role of the ADI system in bacterial survival and virulence and discovered important differences in RF and LD ADIs. Both in vitro and in a murine model of infection, B. hermsii cells significantly reduced extracellular L-arginine levels and that reduction was dependent on arginine deiminase expression. Conversely, B. burgdorferi did not reduce the concentration of L-arginine during in vitro growth experiments nor during infection of the mammalian host, suggesting a fundamental difference in the ability to directly utilize L-arginine compared to B. hermsii. Further experiments using a panel of mutants generated in both B. burgdorferi and B. hermsii, identified important differences in growth characteristics and ADI transcription and protein expression. We also found that the ADI system plays a key role in blood and spleen colonization in RF spirochetes. In this study we have identified divergent metabolic strategies in two closely related human pathogens, that ultimately impacts the host-pathogen interface during infection.
Topics: Animals; Arginine; Borrelia; Borrelia burgdorferi; Humans; Lyme Disease; Mammals; Mice; Relapsing Fever
PubMed: 35286343
DOI: 10.1371/journal.ppat.1010370 -
Frontiers in Immunology 2020Relapsing fever (RF) is claimed a neglected arthropod-borne disease caused by a number of diverse human pathogenic (.) species. These RF borreliae are separated into... (Review)
Review
Relapsing fever (RF) is claimed a neglected arthropod-borne disease caused by a number of diverse human pathogenic (.) species. These RF borreliae are separated into the groups of tick-transmitted species including , and , and the louse-borne species . As typical blood-borne pathogens achieving high cell concentrations in human blood, RF borreliae (RFB) must outwit innate immunity, in particular complement as the first line of defense. One prominent strategy developed by RFB to evade innate immunity involves inactivation of complement by recruiting distinct complement regulatory proteins, e.g., C1 esterase inhibitor (C1-INH), C4b-binding protein (C4BP), factor H (FH), FH-like protein-1 (FHL-1), and factor H-related proteins FHR-1 and FHR-2, or binding of individual complement components and plasminogen, respectively. A number of multi-functional, complement and plasminogen-binding molecules from distinct species have previously been identified and characterized, exhibiting considerable heterogeneity in their sequences, structures, gene localization, and their capacity to bind host-derived proteins. In addition, RFB possess a unique system of antigenic variation, allowing them to change the composition of surface-exposed variable major proteins, thus evading the acquired immune response of the human host. This review focuses on the current knowledge of the immune evasion strategies by RFB and highlights the role of complement-interfering and infection-associated molecules for the pathogenesis of RFB.
Topics: Adaptive Immunity; Antigenic Variation; Bacterial Proteins; Borrelia; Complement System Proteins; Humans; Immune Evasion; Immunity, Innate; Protein Binding; Relapsing Fever
PubMed: 32793216
DOI: 10.3389/fimmu.2020.01560 -
Experimental & Applied Acarology Jul 2022Ixodes ricinus ticks transmit Borrelia burgdorferi sensu lato (s.l.) as well as Borrelia miyamotoi. Larvae become infected when feeding on infected rodents, with...
Ixodes ricinus ticks transmit Borrelia burgdorferi sensu lato (s.l.) as well as Borrelia miyamotoi. Larvae become infected when feeding on infected rodents, with horizontal transmission of B. burgdorferi and horizontal and vertical transmission of B. miyamotoi. We studied seasonal dynamics of infection rates of I. ricinus and their rodent hosts, and hence transmission risk of these two distinctly different Borrelia species. Rodents were live-trapped and inspected for ticks from May to November in 2013 and 2014 in a forest in The Netherlands. Trapped rodents were temporarily housed in the laboratory and detached ticks were collected. Borrelia infections were determined from the trapped rodents and collected ticks. Borrelia burgdorferi s.l. and B. miyamotoi were found in ticks as well as in rodents. Rodent density was higher in 2014, whereas tick burden as well as the Borrelia infection rates in rodents were higher in 2013. The density of B. miyamotoi-infected nymphs did not differ between the years. Tick burdens were higher on Apodemus sylvaticus than on Myodes glareolus, and higher on males than on females. Borrelia-infection rate of rodents varied strongly seasonally, peaking in summer. As the larval tick burden also peaked in summer, the generation of infected nymphs was highest in summer. We conclude that the heterogeneity of environmental and host-specific factors affects the seasonal transmission of Borrelia spp., and that these effects act more strongly on horizontally transmitted B. burgdorferi spp. than on the vertically transmitted B. miyamotoi.
Topics: Animals; Borrelia; Borrelia Infections; Borrelia burgdorferi; Ecosystem; Female; Forests; Ixodes; Lyme Disease; Male; Murinae; Nymph; Seasons
PubMed: 35840866
DOI: 10.1007/s10493-022-00720-z -
The American Journal of Tropical... Aug 2013The study of relapsing fever borreliae in Africa has long suffered from the use of non-specific laboratory tools for the direct detection of these spirochetes in... (Review)
Review
The study of relapsing fever borreliae in Africa has long suffered from the use of non-specific laboratory tools for the direct detection of these spirochetes in clinical and vector specimens. Accordingly, Borrelia hispanica, Borrelia crocidurae, Borrelia duttonii, and Borrelia recurrentis have traditionally been distinguished on the basis of geography and vector and the unproven hypothesis that each species was exclusive to one vector. The recent sequencing of three relapsing fever Borrelia genomes in our laboratory prompted the development of more specific tools and a reappraisal of the epidemiology in Africa. Five additional potential species still need to be cultured from clinical and vector sources in East Africa to further assess their uniqueness. Here, we review the molecular evidence of relapsing fever borreliae in hosts and ectoparasites in Africa and explore the diversity, geographical distribution, and vector association of these pathogens for Africans and travelers to Africa.
Topics: Africa; Animals; Borrelia; Disease Vectors; Humans; Relapsing Fever
PubMed: 23926141
DOI: 10.4269/ajtmh.12-0691 -
Parasites & Vectors Jul 2021Lyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important...
BACKGROUND
Lyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important indicator of risk assessment and of differences in pathogenicity in humans. The objective of our study was to assess the prevalence, co-infection and distribution of Borrelia and Babesia species in ticks removed from humans in a large sample collected during a study period of 4 years.
METHODS
The ticks were collected throughout Poland from March to November over 4-year period from 2016 to 2019. All ticks (n = 1953) were morphologically identified in terms of species and developmental stage. Molecular screening for Borrelia and Babesia by amplification of the flagellin gene (flaB) or 18S rRNA marker was performed. Pathogen identity was confirmed by Sanger sequencing or PCR-restriction fragment length polymorphism analysis.
RESULTS
The ticks removed from humans in Poland during this study belonged to two species: Ixodes ricinus (97%) and Dermacentor reticulatus (3%). High Borrelia prevalence (25.3%), including B. miyamotoi (8.4%), was confirmed in Ixodes ricinus ticks removed from humans, as was the change in frequency of occurrence of Borrelia species during the 4-year study. Despite Babesia prevalence being relatively low (1.3%), the majority of tested isolates are considered to be pathogenic to humans. Babesia infection was observed more frequently among Borrelia-positive ticks (2.7%) than among ticks uninfected with Borrelia (0.8%). The most frequent dual co-infections were between Borrelia afzelii and Babesia microti. The presence of Borrelia was also confirmed in D. reticulatus (12.7%); however the role of these ticks in spirochete transmission to susceptible hosts is still unclear.
CONCLUSIONS
Although the overall risk of developing LB after a tick bite is low in Europe, knowledge of the prevalence and distribution of Borrelia and Babesia species in ticks might be an important indicator of the risk of both these tick-borne diseases.
Topics: Animals; Babesia; Babesiosis; Borrelia; Coinfection; Female; Humans; Ixodes; Longitudinal Studies; Lyme Disease; Male; Poland; Prevalence; Tick-Borne Diseases
PubMed: 34210355
DOI: 10.1186/s13071-021-04849-5 -
Clinical Infectious Diseases : An... Jun 2018Tick-transmitted Borrelia fall into 2 heterogeneous bacterial complexes comprised of multiple species, the relapsing fever (RF) group and the Borrelia burgdorferi sensu...
BACKGROUND
Tick-transmitted Borrelia fall into 2 heterogeneous bacterial complexes comprised of multiple species, the relapsing fever (RF) group and the Borrelia burgdorferi sensu lato group, which are the causative agents of Lyme borreliosis (LB), the most common tickborne disease in the Northern Hemisphere. Geographic expansion of LB in the United States and discovery of emerging Borrelia pathogens underscores the importance of surveillance for disease-causing Borrelia.
METHODS
De-identified clinical specimens, submitted by providers throughout the United States, for patients suspected of LB, anaplasmosis, ehrlichiosis, or babesiosis were screened using a Borrelia genus-level TaqMan polymerase chain reaction (PCR). Borrelia species and sequence types (STs) were characterized by multilocus sequence typing (MLST) utilizing next-generation sequencing.
RESULTS
Among 7292 specimens tested, 5 Borrelia species were identified: 2 causing LB, B. burgdorferi (n = 25) and B. mayonii (n = 9), and 3 RF borreliae, B. hermsii (n = 1), B. miyamotoi (n = 8), and Candidatus B. johnsonii (n = 1), a species previously detected only in the bat tick, Carios kelleyi. ST diversity was greatest for B. burgdorferi-positive specimens, with new STs identified primarily among synovial fluids.
CONCLUSIONS
These results demonstrate that broad PCR screening followed by MLST is a powerful surveillance tool for uncovering the spectrum of disease-causing Borrelia species, understanding their geographic distribution, and investigating the correlation between B. burgdorferi STs and joint involvement. Detection of Candidatus B. johnsonii in a patient with suspected tickborne disease suggests this species may be a previously undetected cause of illness in humans exposed to bat ticks.
Topics: Animals; Bacterial Typing Techniques; Borrelia; Borrelia burgdorferi Group; Chiroptera; Epidemiological Monitoring; Geography; High-Throughput Nucleotide Sequencing; Humans; Ixodes; Lyme Disease; Multilocus Sequence Typing; Polymerase Chain Reaction; Tick-Borne Diseases; United States
PubMed: 29272385
DOI: 10.1093/cid/cix1107 -
FEBS Letters Aug 2020Borreliosis (Lyme disease) is a spirochetal disease caused by the species complex of Borrelia burgdorferi transmitted by Ixodes spp. ticks. Recorded to be the most... (Review)
Review
Borreliosis (Lyme disease) is a spirochetal disease caused by the species complex of Borrelia burgdorferi transmitted by Ixodes spp. ticks. Recorded to be the most common tick-borne disease in the world, the last two decades have seen an increase in disease incidence and distribution, exceeding 360 000 cases in Europe alone. If untreated, infection may cause skin symptoms, arthritis, and neurological or cardiac complications. Borrelia spirochetes have developed strategies to evade the mammalian host immune system. These include the complement system, which is an important first-line defense mechanism against invading microbes. To evade the complement, spirochetes bind soluble complement regulators factor H (FH), factor H-like protein, and C4bp to their outer surfaces. B. burgdorferi spirochetes can inhibit the classical pathway of complement by the outer surface protein (Osp) BBK32, which blocks the activation of the C1 complex, composed of C1q, C1r, and C1s. The FH-binding proteins of borreliae include Osps OspE, CspA, and CspZ. Following repeated infections, antibodies against these proteins develop and may provide functional immunity against borreliosis. This review discusses critical immune evasion strategies, focusing on complement evasion by borreliae.
Topics: Animals; Antibodies, Bacterial; Bacterial Proteins; Borrelia burgdorferi; Complement System Proteins; Humans; Immune Evasion; Lyme Disease
PubMed: 32748966
DOI: 10.1002/1873-3468.13894 -
Trends in Parasitology Jul 2020Lyme disease is the most common vector-borne disease in the northern hemisphere and is caused by spirochetes of the Borrelia burgdorferi sensu lato complex. Lyme... (Review)
Review
Lyme disease is the most common vector-borne disease in the northern hemisphere and is caused by spirochetes of the Borrelia burgdorferi sensu lato complex. Lyme borreliae infect diverse vertebrate reservoirs without triggering apparent manifestations in these animals; however, Lyme borreliae strains differ in their reservoir hosts. The mechanisms that drive those differences are unknown. To survive in vertebrate hosts, Lyme borreliae require the ability to escape from host defense mechanisms, in particular complement. To facilitate the evasion of complement, Lyme borreliae produce diverse proteins at different stages of infection, allowing them to persistently survive without being recognized by hosts and potentially resulting in host-specific infection. This review discusses the current knowledge regarding the ecology and evolutionary mechanisms of Lyme borreliae-host associations driven by complement evasion.
Topics: Animals; Borrelia; Host-Pathogen Interactions; Humans; Immune Evasion; Lyme Disease
PubMed: 32456964
DOI: 10.1016/j.pt.2020.04.011 -
Current Issues in Molecular Biology 2021All members of the genus that have been examined harbour a linear chromosome that is about 900 kbp in length, as well as a plethora of both linear and circular plasmids...
All members of the genus that have been examined harbour a linear chromosome that is about 900 kbp in length, as well as a plethora of both linear and circular plasmids in the 5-220 kbp size range. Genome sequences for 27 Lyme disease isolates have been determined since the elucidation of the B31 genome sequence in 1997. The chromosomes, which carry the vast majority of the housekeeping genes, appear to be very constant in gene content and organization across all Lyme disease species. The content of the plasmids, which carry most of the genes that encode the differentially expressed surface proteins that interact with the spirochete's arthropod and vertebrate hosts, is much more variable. Lyme disease isolates carry between 7-21 different plasmids, ranging in size from 5-84 kbp. All strains analyzed to date harbor three plasmids, cp26, lp54 and lp17. The plasmids are unusual, as compared to most bacterial plasmids, in that they contain many paralogous sequences, a large number of pseudogenes, and, in some cases, essential genes. In addition, a number of the plasmids have features indicating that they are prophages. Numerous methods have been developed for Lyme disease strain typing. These have proven valuable for clinical and epidemiological studies, as well as phylogenomic and population genetic analyses. Increasingly, these approaches have been displaced by whole genome sequencing techniques. Some correlations between genome content and pathogenicity have been deduced, and comparative whole genome analyses promise future progress in this arena.
Topics: Borrelia; Disease Susceptibility; Gene Expression Regulation, Bacterial; Genome, Bacterial; Genomics; Host-Pathogen Interactions; Humans; Lyme Disease; Molecular Typing; Plasmids; Prophages; Whole Genome Sequencing
PubMed: 33328355
DOI: 10.21775/cimb.042.409