scholarly journals Host specialization in microparasites transmitted by generalist vectors: insights into the cellular and immunological mechanisms

2020 ◽  
Author(s):  
Yi-Pin Lin ◽  
Danielle M. Tufts ◽  
Alan P. Dupuis ◽  
Matthew Combs ◽  
Ashley L. Marcinkiewicz ◽  
...  

ABSTRACTHost specialization is an ecological and evolutionary process by which a pathogen becomes differentially adapted to a subset of hosts, restricting its host range. For parasites transmitted by generalist vectors, host specialization is not expected to evolve because of the decreased survival of those parasites in inadequate hosts. Thus, parasites may develop adaptation strategies, resulting in host specialization. The causative agents of Lyme disease are multiple species of bacteria, Borrelia burgdorferi sensu lato species complex (Bbsl), and are suitable for examining host specialization as birds and rodents were found to carry different species of these bacteria. Debate exists on whether host specialization occurs among these strains within a particular species of Bbsl, such as B. burgdorferi sensu stricto (Bbss). Current evidence supports some Bbss strains are widespread in white-footed mice but others are in non-rodent vertebrates, such as birds. To recapitulate specialization in the laboratory and define the mechanisms for host specialization, we introduced different genotypes of Bbss via tick transmission to American robins and white-footed mice, the Lyme disease reservoirs in North America. Among these strains, we found distinct levels of spirochete presence in the bloodstream and tissues and maintenance by these animals in a host-dependent fashion. We showed that the late stage persistence of these strains largely corresponds to bacterial survival at early infection onsets. We also demonstrated that those early survival phenotypes correspond to spirochete adhesiveness, evasion of complement-mediated killing in sera, and/or not triggering high levels of pro-inflammatory cytokines and antibodies. Our findings thus link host competence to Bbss with spirochete genotypic variation of adhesiveness and inducing/escaping host immune responses, illuminating the potential mechanisms that dictate host specialization. Such information will provide a foundation for further investigation into multi-disciplinary processes driving host specialization of microparasites.AUTHOR SUMMARYHost specialization arises when microparasites adapt to a subset of available hosts, restricting the host ranges they can infect. The mechanisms and selective pressures for the evolution of host specialization remain unclear. The causative agent of Lyme disease (LD), the bacteria species complex of Borrelia burgdorferi sensu lato, is adapted to different vertebrates. However, whether such a differential host adaption also applies to each genotype within the same species is under debate. Further, the mechanisms that drive such host specialization are unclear. We thus introduced three genotypes of one LD bacteria species (B. burgdorferi sensu stricto) individually via tick bite to American robins and white-footed mice, the most common LD reservoirs in North America. We found that these genotypes differed in the persistent maintenance by those reservoirs and occurred in a host-specific fashion. The ability of those bacteria for long-term maintenance was linked with their capability to attach to cells and a lack of induction of high levels of immune responses at early infection onsets. This work demonstrates the potential mechanisms that dictate host specialization of LD bacteria circulating in natural populations. Such information will pave the road to define the molecular, ecological, and evolutionary determinants that drive host-microparasite interactions.

2012 ◽  
Vol 19 (4) ◽  
pp. 527-535 ◽  
Author(s):  
Bettina Wagner ◽  
Heather Freer ◽  
Alicia Rollins ◽  
David Garcia-Tapia ◽  
Hollis N. Erb ◽  
...  

ABSTRACTLyme disease in the United States is caused byBorrelia burgdorferisensu stricto, which is transmitted to mammals by infected ticks.Borreliaspirochetes differentially express immunogenic outer surface proteins (Osp). Our aim was to evaluate antibody responses to Osp antigens to aid the diagnosis of early infection and the management of Lyme disease. We analyzed antibody responses during the first 3 months after the experimental infection of dogs using a novel multiplex assay. Results were compared to those obtained with two commercial assays detecting C6 antigen. Multiplex analysis identified antibodies to OspC and C6 as early as 3 weeks postinfection (p.i.) and those to OspF by 5 weeks p.i. Antibodies to C6 and OspF increased throughout the study, while antibodies to OspC peaked between 7 and 11 weeks p.i. and declined thereafter. A short-term antibody response to OspA was observed in 3/8 experimentally infected dogs on day 21 p.i. Quant C6 enzyme-linked immunosorbent assay (ELISA) results matched multiplex results during the first 7 weeks p.i.; however, antibody levels subsequently declined by up to 29%. Immune responses then were analyzed in sera from 125 client-owned dogs and revealed high agreement between antibodies to OspF and C6 as robust markers for infection. Results from canine patient sera supported that OspC is an early infection marker and antibodies to OspC decline over time. The onset and decline of antibody responses toB. burgdorferiOsp antigens and C6 reflect their differential expression during infection. They provide valuable tools to determine the stage of infection, treatment outcomes, and vaccination status in dogs.


2014 ◽  
Vol 64 (Pt_1) ◽  
pp. 128-130 ◽  
Author(s):  
Gabriele Margos ◽  
Joseph Piesman ◽  
Robert S. Lane ◽  
Nicholas H. Ogden ◽  
Andreas Sing ◽  
...  

Lyme borreliosis group spirochaetes are parasitic bacteria transmitted by vector ticks of the genus Ixodes and distributed mainly between 40° and 60° northern latitudes. Since Borrelia burgdorferi sensu stricto (hereinafter, B. burgdorferi ) was described in the north-eastern USA during the early 1980s, an increasing diversity has been noted within the species complex. Here, we describe a novel genomic species, Borrelia kurtenbachii sp. nov. (type strain 25015T = ATCC BAA-2495T =  DSM 26572T), that is prevalent in transmission cycles among vector ticks and reservoir hosts in North America. Confirmation of the presence of this species in Europe awaits further investigation.


Parasitology ◽  
2016 ◽  
Vol 143 (10) ◽  
pp. 1310-1319 ◽  
Author(s):  
SANNE C. RUYTS ◽  
EVY AMPOORTER ◽  
ELENA C. COIPAN ◽  
LANDER BAETEN ◽  
DIETER HEYLEN ◽  
...  

SUMMARYLyme disease is caused by bacteria of theBorrelia burgdorferigenospecies complex and transmitted by Ixodid ticks. In North America only one pathogenic genospecies occurs, in Europe there are several. According to the dilution effect hypothesis (DEH), formulated in North America, nymphal infection prevalence (NIP) decreases with increasing host diversity since host species differ in transmission potential. We analysedBorreliainfection in nymphs from 94 forest stands in Belgium, which are part of a diversification gradient with a supposedly related increasing host diversity: from pine stands without to oak stands with a shrub layer. We expected changing tree species and forest structure to increase host diversity and decrease NIP. In contrast with the DEH, NIP did not differ between different forest types. Genospecies diversity however, and presumably also host diversity, was higher in oak than in pine stands. Infected nymphs tended to harbourBorrelia afzeliiinfection more often in pine stands whileBorrelia gariniiandBorrelia burgdorferiss. infection appeared to be more prevalent in oak stands. This has important health consequences, since the latter two cause more severe disease manifestations. We show that the DEH must be nuanced for Europe and should consider the response of multiple pathogenic genospecies.


2002 ◽  
Vol 70 (6) ◽  
pp. 3300-3303 ◽  
Author(s):  
Fang Ting Liang ◽  
F. Kenneth Nelson ◽  
Erol Fikrig

ABSTRACT A DNA microarray containing fragments of 137 Borrelia burgdorferi B31 putative lipoprotein genes was used to examine Lyme disease spirochetes. DNA from B. burgdorferi sensu stricto B31, 297, and N40; Borrelia garinii IP90; and Borrelia afzelii P/Gau was fluorescently labeled and hybridized to the microarray, demonstrating the degree to which the individual putative lipoprotein genes were conserved among the genospecies. These data show that a DNA microarray can globally examine the genes encoding B. burgdorferi lipoproteins.


Healthcare ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 89 ◽  
Author(s):  
John Scott ◽  
Kerry Clark ◽  
Janet Foley ◽  
Bradley Bierman ◽  
Lance Durden

Lyme disease has been documented in northern areas of Canada, but the source of the etiological bacterium, Borrelia burgdorferi sensu lato (Bbsl) has been in doubt. We collected 87 ticks from 44 songbirds during 2017, and 24 (39%) of 62 nymphs of the blacklegged tick, Ixodes scapularis, were positive for Bbsl. We provide the first report of Bbsl-infected, songbird-transported I. scapularis in Cape Breton, Nova Scotia; Newfoundland and Labrador; north-central Manitoba, and Alberta. Notably, we report the northernmost account of Bbsl-infected ticks parasitizing a bird in Canada. DNA extraction, PCR amplification, and DNA sequencing reveal that these Bbsl amplicons belong to Borrelia burgdorferi sensu stricto (Bbss), which is pathogenic to humans. Based on our findings, health-care providers should be aware that migratory songbirds widely disperse B. burgdorferi-infected I. scapularis in Canada’s North, and local residents do not have to visit an endemic area to contract Lyme disease.


Healthcare ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 155 ◽  
Author(s):  
John D. Scott ◽  
Kerry L. Clark ◽  
Nikki M. Coble ◽  
Taylor R. Ballantyne

Lyme disease and human babesiosis are the most common tick-borne zoonoses in the Temperate Zone of North America. The number of infected patients has continued to rise globally, and these zoonoses pose a major healthcare threat. This tick-host-pathogen study was conducted to test for infectious microbes associated with Lyme disease and human babesiosis in Canada. Using the flagellin (flaB) gene, three members of the Borrelia burgdorferi sensu lato (Bbsl) complex were detected, namely a Borrelia lanei-like spirochete, Borrelia burgdorferi sensu stricto (Bbss), and a distinct strain that may represent a separate Bbsl genospecies. This novel Bbsl strain was detected in a mouse tick, Ixodes muris, collected from a House Wren, Troglodytes aedon, in Quebec during the southward fall migration. The presence of Bbsl in bird-feeding larvae of I. muris suggests reservoir competency in three passerines (i.e., Common Yellowthroat, House Wren, Magnolia Warbler). Based on the 18S ribosomal RNA (rRNA) gene, three Babesia species (i.e., Babesia divergens-like, Babesia microti, Babesia odocoilei) were detected in field-collected ticks. Not only was B. odocoilei found in songbird-derived ticks, this piroplasm was apparent in adult questing blacklegged ticks, Ixodes scapularis, in southern Canada. By allowing live, engorged ticks to molt, we confirm the transstadial passage of Bbsl in I. muris and B. odocoilei in I. scapularis. Bbss and Babesia microti were detected concurrently in a groundhog tick, Ixodes cookei, in Western Ontario. In Alberta, a winter tick, Dermacentor albipictus, which was collected from a moose, Alces alces, tested positive for Bbss. Notably, a B. divergens-like piroplasm was detected in a rabbit tick, Haemaphysalis leporispalustris, collected from an eastern cottontail in southern Manitoba; this Babesia species is a first-time discovery in Canada. This rabbit tick was also co-infected with Borrelia lanei-like spirochetes, which constitutes a first in Canada. Overall, five ticks were concurrently infected with Babesia and Bbsl pathogens and, after the molt, could potentially co-infect humans. Notably, we provide the first authentic report of I. scapularis ticks co-infected with Bbsl and B. odocoilei in Canada. The full extent of infectious microorganisms transmitted to humans by ticks is not fully elucidated, and clinicians need to be aware of the complexity of these tick-transmitted enzootic agents on human health. Diagnosis and treatment must be administered by those with accredited medical training in tick-borne zoonosis.


2013 ◽  
Vol 20 (4) ◽  
pp. 474-481 ◽  
Author(s):  
Paul M. Arnaboldi ◽  
Rudra Seedarnee ◽  
Mariya Sambir ◽  
Steven M. Callister ◽  
Josephine A. Imparato ◽  
...  

ABSTRACTCurrent serodiagnostic assays for Lyme disease are inadequate at detecting early infection due to poor sensitivity and nonspecificity that arise from the use of whole bacteria or bacterial proteins as assay targets; both targets contain epitopes that are cross-reactive with epitopes found in antigens of other bacterial species. Tests utilizing peptides that contain individual epitopes highly specific forBorrelia burgdorferias diagnostic targets are an attractive alternative to current assays. Using an overlapping peptide library, we mapped linear epitopes in OspC, a critical virulence factor ofB. burgdorferirequired for mammalian infection, and confirmed the results by enzyme-linked immunosorbent assay (ELISA). We identified a highly conserved 20-amino-acid peptide epitope, OspC1. Via ELISA, OspC1 detected specific IgM and/or IgG in 60 of 98 serum samples (62.1%) obtained from patients with erythema migrans (early Lyme disease) at the time of their initial presentation. By comparison, the commercially available OspC peptide PepC10 detected antibody in only 48 of 98 serum samples (49.0%). In addition, OspC1 generated fewer false-positive results among negative healthy and diseased (rheumatoid arthritis and positive Rapid Plasma Reagin [RPR+] test result) control populations than did PepC10. Both highly specific and more sensitive than currently available OspC peptides, OspC1 could have value as a component of a multipeptide Lyme disease serological assay with significantly improved capabilities for the diagnosis of early infection.


1998 ◽  
Vol 36 (11) ◽  
pp. 3127-3132 ◽  
Author(s):  
Chien-Ming Shih ◽  
Han-Ming Chang ◽  
Show-Li Chen ◽  
Li-Lian Chao

Lyme disease spirochetes of the genospecies Borrelia burgdorferi sensu lato were identified and characterized for the first time in Taiwan. Seven isolates, designated TWKM1 to TWKM7, were purified from the ear tissues of three species of rodents captured from seven localities of Taiwan. The immunological characteristics of these Taiwan isolates were compared with those of other genospecies of Lyme disease spirochetes by analyzing the protein profiles and reactivities with B. burgdorferi-specific monoclonal antibodies (MAbs). The genospecies of these Taiwan isolates were also identified by the similarities in their plasmid profiles and differential reactivities with genospecies-specific PCR primers. Although two distinct protein profiles were observed among the seven Taiwan isolates, the MAb reactivities against the outer surface proteins of B. burgdorferi of all of these isolates were consistent with those of B. burgdorferi sensu lato. The similarities of the plasmid profiles also confirmed the identities of these Taiwan isolates. PCR analysis indicated that all of these Taiwan isolates were genetically related to the genospecies B. burgdorferi sensu stricto. These results demonstrate the first identification of Lyme disease spirochetes in Taiwan and also highlight the increasing demand for defining the reservoirs and vector ticks of B. burgdorferi. A serosurvey for Lyme disease infection in the human population of Taiwan may also be required.


1998 ◽  
Vol 66 (5) ◽  
pp. 2143-2153 ◽  
Author(s):  
Mark S. Hanson ◽  
David R. Cassatt ◽  
Betty P. Guo ◽  
Nita K. Patel ◽  
Michael P. McCarthy ◽  
...  

ABSTRACT Borrelia burgdorferi, the spirochete that causes Lyme disease, binds decorin, a collagen-associated extracellular matrix proteoglycan found in the skin (the site of entry for the spirochete) and in many other tissues. Two borrelial adhesins that recognize this proteoglycan, decorin binding proteins A and B (DbpA and DbpB, respectively), have recently been identified. Infection of mice by low-dose B. burgdorferi challenge elicited antibodies against DbpA and DbpB that were sustained at high levels, suggesting that these antigens are expressed in vivo. Scanning immunoelectron microscopy showed that DbpA was surface accessible on intact borreliae. Passive administration of DbpA antiserum protected mice from infection following challenge with heterologous B. burgdorferi sensu stricto isolates, even when serum administration was delayed for up to 4 days after challenge. DbpA is the first antigen target identified that is capable of mediating immune resolution of early, localizedB. burgdorferi infections. DbpA immunization also protected mice from B. burgdorferi challenge; DbpB immunization was much less effective. DbpA antiserum inhibited in vitro growth of manyB. burgdorferi sensu lato isolates of diverse geographic, phylogenetic, and clinical origins. In combination, these findings support a role for DbpA in the immunoprophylaxis of Lyme disease and suggest that DbpA vaccines have the potential to eliminate early-stageB. burgdorferi infections.


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