Dataset Information

Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding.

ABSTRACT: Additional research on soft ticks in the family Argasidae is needed to bridge the knowledge gap relative to hard ticks of the family Ixodidae; especially, the molecular mechanisms of Ornithodoros biology. Ornithodoros species are vectors of human and animal pathogens that include tick-borne relapsing fever spirochetes and African swine fever virus. Soft tick vector-pathogen interactions involving components of the tick immune response are not understood. Ticks utilize a basic innate immune system consisting of recognition factors and cellular and humoral responses to produce antimicrobial peptides, like defensins. In the present study, we identified and characterized the first putative defensins of Ornithodoros turicata, an argasid tick found primarily in the southwestern United States and regions of Latin America. Four genes (otdA, otdB, otdC, and otdD) were identified through sequencing and their predicted amino acid sequences contained motifs characteristic of arthropod defensins. A phylogenetic analysis grouped these four genes with arthropod defensins, and computational structural analyses further supported the identification. Since pathogens transmitted by O. turicata colonize both the midgut and salivary glands, expression patterns of the putative defensins were determined in these tissues 1 week post engorgement and after molting. Defensin genes up-regulated in the tick midgut 1 week post blood feeding were otdA and otdC, while otdD was up-regulated in the midgut of post-molt ticks. Moreover, otdB and otdD were also up-regulated in the salivary glands of flat post-molt ticks, while otdC was up-regulated within 1 week post blood-feeding. This work is foundational toward additional studies to determine mechanisms of vector competence and pathogen transmission from O. turicata.

SUBMITTER: Armstrong BA

PROVIDER: S-EPMC7232577 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding.

Armstrong Brittany A BA Kneubehl Alexander R AR Mitchell Robert D RD Krishnavajhala Aparna A Teel Pete D PD Pérez de León Adalberto A AA Lopez Job E JE

Frontiers in cellular and infection microbiology 20200505

Additional research on soft ticks in the family Argasidae is needed to bridge the knowledge gap relative to hard ticks of the family Ixodidae; especially, the molecular mechanisms of Ornithodoros biology. Ornithodoros species are vectors of human and animal pathogens that include tick-borne relapsing fever spirochetes and African swine fever virus. Soft tick vector-pathogen interactions involving components of the tick immune response are not understood. Ticks utilize a basic innat ...[more]

PMID: 32477960

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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.

Project description:The general bacterial microbiota of the soft tick Ornithodoros turicata found on Bolson tortoises (Gopherus flavomarginatus) were analyzed using next generation sequencing. The main aims of the study were to establish the relative abundance of bacterial taxa in the tick, and to document the presence of potentially pathogenic species for this tortoise, other animals, and humans. The study was carried-out in the Mapimi Biosphere Reserve in the northern-arid part of Mexico. Bolson tortoises (n = 45) were inspected for the presence of soft ticks, from which 11 tortoises (24.4%) had ticks in low loads (1-3 ticks per individual). Tick pools (five adult ticks each) were analyzed through 16S rRNA V3-V4 region amplification in a MiSeq Illumina, using EzBioCloud as a taxonomical reference. The operational taxonomic units (OTUs) revealed 28 phyla, 84 classes, 165 orders, 342 families, 1013 genera, and 1326 species. The high number of taxa registered for O. turicata may be the result of the variety of hosts that this tick parasitizes as they live inside G. flavomarginatus burrows. While the most abundant phyla were Proteobacteria, Actinobacteria, and Firmicutes, the most abundant species were two endosymbionts of ticks (Midichloria-like and Coxiella-like). Two bacteria documented as pathogenic to Gopherus spp. were registered (Mycoplasma spp. and Pasteurella testudinis). The bovine and ovine tick-borne pathogens A. marginale and A. ovis, respectively, were recorded, as well as the zoonotic bacteria A. phagocytophilum,Coxiella burnetii, and Neoehrlichia sp. Tortoises parasitized with O. turicata did not show evident signs of disease, which could indicate a possible ecological role as a reservoir that has yet to be demonstrated. In fact, the defense mechanisms of this tortoise against the microorganisms transmitted by ticks during their feeding process are still unknown. Future studies on soft ticks should expand our knowledge about what components of the microbiota are notable across multiple host-microbe dynamics. Likewise, studies are required to better understand the host competence of this tortoise, considered the largest terrestrial reptile in North America distributed throughout the Chihuahuan Desert since the late Pleistocene.

Project description:BackgroundSubolesin is an evolutionary conserved molecule in diverse arthropod species that play an important role in the regulation of genes involved in immune responses, blood digestion, reproduction and development. In this study, we have identified a subolesin ortholog from soft ticks Ornithodoros turicata, the vector of the relapsing fever spirochete in the United States.MethodsUninfected fed or unfed O. turicata ticks were used throughout this study. The subolesin mRNA was amplified by reverse transcription polymerase chain reaction (RT-PCR) and sequenced. Quantitative-real time PCR (QRT-PCR) was performed to evaluate subolesin mRNA levels at different O. turicata developmental stages and from salivary glands and gut tissues. Bioinformatics and comparative analysis was performed to predict potential post-translational modifications in O. turicata subolesin amino-acid sequences.ResultsOur study reveals that O. turicata subolesin gene expression is developmentally regulated, where; adult ticks expressed significantly higher levels in comparison to the larvae or nymphal ticks. Expression of subolesin was evident in both unfed and fed ticks and in the salivary glands and midgut tissues. The expression of subolesin transcripts varied in fed ticks with peak levels at day 14 post-feeding. Phylogenetic analysis revealed that O. turicata subolesin showed a high degree of sequence conservation with subolesin's from other soft and hard ticks. Bioinformatics and comparative analysis predicted that O. turicata subolesin carry three Protein kinase C and one Casein kinase II phosphorylation sites. However, no myristoylation or glycosylation sites were evident in the O. turicata subolesin sequence.ConclusionOur study provides important insights in recognizing subolesin as a conserved potential candidate for the development of a broad-spectrum anti-vector vaccine to control not only ticks but also several other arthropods that transmit diseases to humans and animals.

Dataset Information

Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding.

Publications

Differential Expression of Putative <i>Ornithodoros turicata</i> Defensins Mediated by Tick Feeding.

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