Dataset Information

Development of genetic system to inactivate a Borrelia turicatae surface protein selectively produced within the salivary glands of the arthropod vector.

ABSTRACT:

Background

Borrelia turicatae, an agent of tick-borne relapsing fever, is an example of a pathogen that can adapt to disparate conditions found when colonizing the mammalian host and arthropod vector. However, little is known about the genetic factors necessary during the tick-mammalian infectious cycle, therefore we developed a genetic system to transform this species of spirochete. We also identified a plasmid gene that was up-regulated in vitro when B. turicatae was grown in conditions mimicking the tick environment. This 40 kilodalton protein was predicted to be surface localized and designated the Borrelia repeat protein A (brpA) due to the redundancy of the amino acid motif Gln-Gly-Asn-Val-Glu.

Methodology/principal findings

Quantitative reverse-transcriptase polymerase chain reaction using RNA from B. turicatae infected ticks and mice indicated differential regulation of brpA during the tick-mammalian infectious cycle. The surface localization was determined, and production of the protein within the salivary glands of the tick was demonstrated. We then applied a novel genetic system for B. turicatae to inactivate brpA and examined the role of the gene product for vector colonization and the ability to establish murine infection.

Conclusions/significance

These results demonstrate the complexity of protein production in a population of spirochetes within the tick. Additionally, the development of a genetic system is important for future studies to evaluate the requirement of specific B. turicatae genes for vector colonization and transmission.

SUBMITTER: Lopez JE

PROVIDER: S-EPMC3814808 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Publications

Development of genetic system to inactivate a Borrelia turicatae surface protein selectively produced within the salivary glands of the arthropod vector.

Lopez Job E JE Wilder Hannah K HK Hargrove Reid R Brooks Christopher P CP Peterson Karin E KE Beare Paul A PA Sturdevant Daniel E DE Nagarajan Vijayaraj V Raffel Sandra J SJ Schwan Tom G TG

PLoS neglected tropical diseases 20131031 10

<h4>Background</h4>Borrelia turicatae, an agent of tick-borne relapsing fever, is an example of a pathogen that can adapt to disparate conditions found when colonizing the mammalian host and arthropod vector. However, little is known about the genetic factors necessary during the tick-mammalian infectious cycle, therefore we developed a genetic system to transform this species of spirochete. We also identified a plasmid gene that was up-regulated in vitro when B. turicatae was grown in condition ...[more]

PMID: 24205425

Similar Datasets

Project description:BackgroundWith the global distribution, morbidity, and mortality associated with tick and louse-borne relapsing fever spirochetes, it is important to understand the dynamics of vector colonization by the bacteria and transmission to the host. Tick-borne relapsing fever spirochetes are blood-borne pathogens transmitted through the saliva of soft ticks, yet little is known about the transmission capability of these pathogens during the relatively short bloodmeal. This study was therefore initiated to understand the transmission dynamics of the relapsing fever spirochete Borrelia turicatae from the vector Ornithodoros turicata, and the subsequent dissemination of the bacteria upon entry into murine blood.Methodology/principal findingsTo determine the minimum number of ticks required to transmit spirochetes, one to three infected O. turicata were allowed to feed to repletion on individual mice. Murine infection and dissemination of the spirochetes was evaluated by dark field microscopy of blood, quantitative PCR, and immunoblotting against B. turicatae protein lysates and a recombinant antigen, the Borrelia immunogenic protein A. Transmission frequencies were also determined by interrupting the bloodmeal 15 seconds after tick attachment. Scanning electron microscopy (SEM) was performed on infected salivary glands to detect spirochetes within acini lumen and excretory ducts. Furthermore, spirochete colonization and dissemination from the bite site was investigated by feeding infected O. turicata on the ears of mice, removing the attachment site after engorment, and evaluating murine infection.Conclusion/significanceOur findings demonstrated that three ticks provided a sufficient infectious dose to infect nearly all animals, and B. turicatae was transmitted within seconds of tick attachment. Spirochetes were also detected in acini lumen of salivary glands by SEM. Upon host entry, B. turicatae did not require colonization of the bite site to establish murine infection. These results suggest that once B. turicatae colonizes the salivary glands the spirochetes are preadapted for rapid entry into the mammal.

Project description:Vector competence refers to the ability of an arthropod to acquire, maintain, and successfully transmit a microbial pathogen. Tick-borne relapsing fever (TBRF) spirochetes are globally distributed pathogens, and most species are transmitted by argasid ticks of the genus Ornithodoros. A defining characteristic in vector competence is an apparent specificity of a species of TBRF spirochete to a given tick species. In arid regions of the southern United States, Borrelia turicatae is the primary cause of TBRF. Interestingly, there are two populations of the tick vector distributed throughout this region. Ornithodoros turicata is a western population that ranges from California to Texas. There is a gap through Louisiana, Mississippi, and Alabama where the tick has not been identified. An isolated eastern population exists in Florida and was designated a subspecies, O. turicata americanus. A knowledge gap that exists is the poor understanding of vector competence between western and eastern populations of ticks for B. turicatae. In this study, we generated uninfected colonies of O. turicata that originated in Texas and Kansas and of O. turicataamericanus. B. turicatae acquisition, maintenance through the molt, and subsequent transmission were evaluated. Our findings revealed significant differences in murine infection after feeding infected O. turicata and O. turicataamericanus ticks on the animals. Interestingly, the salivary glands of both tick populations were colonized with B. turicatae to similar densities. Our results suggest that the salivary glands of the tick colonies assessed in this study impact vector competence of the evaluated B. turicatae isolates.IMPORTANCE Several knowledge gaps exist in the vector competence of various geographical populations of O. turicata that transmit B. turicatae A western population of this tick is distributed from California to Texas, and an eastern population exists in Florida. Utilizing western and eastern populations of the vector, we studied acquisition and transmission of two B. turicatae isolates. Regardless of the isolate used, infection frequencies were poor in mice after the eastern population feeding on them. Since salivary gland colonization is essential for B. turicatae transmission, these tissues were further evaluated. Interestingly, the salivary glands from the two populations were similarly colonized with B. turicatae. These findings suggest the role of tick saliva in the establishment of infection and that the salivary glands may be a bottleneck for successful transmission.

Dataset Information

Development of genetic system to inactivate a Borrelia turicatae surface protein selectively produced within the salivary glands of the arthropod vector.

Background

Methodology/principal findings

Conclusions/significance

Publications

Development of genetic system to inactivate a Borrelia turicatae surface protein selectively produced within the salivary glands of the arthropod vector.

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