Vector Competence of Geographical Populations of Ornithodoros turicata for the Tick-Borne Relapsing Fever Spirochete Borrelia turicatae

Abstract

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 in the genus 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, is the primary cause of TBRF. Interestingly, there are two populations of the tick vector distributed throughout this region. 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, A knowledge gap that exists is the poor understanding of vector competence between western and eastern populations of tick for In this study, we generated uninfected colonies of that originated in Texas and Kansas and acquisition, maintenance through the molt, and subsequent transmission was evaluated. Our findings revealed significant differences in murine infection after feeding infected and on the animals. Interestingly, the salivary glands of both tick populations were colonized with to similar densities. Our results suggest that the salivary glands of the tick colonies assessed in this study impact vector competence of the evaluated isolates.Several knowledge gaps exist in vector competence of various geographical populations of that transmit A western population of 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 isolates. Regardless of the isolate used, infection frequencies were poor in mice after feeding the eastern population. Since salivary gland colonization is essential for transmission, these tissues were further evaluated. Interestingly, the salivary glands from both populations were similarly colonized with These findings suggest the role of tick saliva in the establishment of infection and that the salivary glands may be a bottle neck for successful transmission.

Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding

“…Primers against the defensins for qPCR ( Table 1) were designed using the sequences from RACE sequencing and were synthesized by Integrated DNA Technologies (Coralville, IA). Defensins were run in duplex with O. turicata β-actin (Krishnavajhala et al, 2018), using the SsoAdvanced Universal Probes Supermix (Bio-Rad, Hercules, CA). Assays were performed with primers and probes at a concentration of 400 and 300 nM, respectively.…”

The impact of in vitro cultivation on the natural life cycle of the tick-borne relapsing fever spirochete Borrelia turicatae

“…Quantification of flaB relative to β-actin was performed in duplex qPCR assays to detect B . turicatae DNA, as preciously described [ 19 ]. An unpaired samples t-test was performed using Graphpad Prism 7.04 to determine if there was a significant difference in B .…”

“…A given assay had 4 to 5 biological replicates per tissue. Each replicate consisted of midguts or salivary glands from five ticks, and gDNA was extracted using the DNeasy Blood and Tissue kit (Qiagen, Hilden, Germany), as previously described [19]. Quantification of flaB relative to β-actin was performed in duplex qPCR assays to detect B. turicatae DNA, as preciously described [19].…”

“…Each replicate consisted of midguts or salivary glands from five ticks, and gDNA was extracted using the DNeasy Blood and Tissue kit (Qiagen, Hilden, Germany), as previously described [19]. Quantification of flaB relative to β-actin was performed in duplex qPCR assays to detect B. turicatae DNA, as preciously described [19]. An unpaired samples t-test was performed using Graphpad Prism 7.04 to determine if there was a significant difference in B. turicatae flaB copies between midgut tissues of ticks colonized with different generations of spirochete.…”

“…Our findings also suggest that RF spirochetes do not transiently migrate through the midgut to colonize salivary glands. In flat persistently infected O. turicata, two spirochete populations are detected, one in the midgut and the other in the salivary glands [19]. Interestingly, the midgut population can be detected in ticks starved over 18 months [19]; however, their role in pathogenesis remains unclear.…”