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Unraveling vector ecology and genomic drivers of vertical transmission: Defining relapsing fever Borrelia persistence in populations of the under-studied argasid tick, Ornithodoros turicata

Award Number: R21AI191624
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 05/05/2026
PERIOD OF PERFORMANCE END DATE: 04/30/2028

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Unraveling vector ecology and genomic drivers of vertical transmission: Defining relapsing fever Borrelia persistence in populations of the under-studied argasid tick, Ornithodoros turicata - Project Summary/Abstract: Despite the CDC’s increased awareness of tick-borne disease in the United States, the current framework does not fully address the public health significance of argasid (Ornithodoros) ticks and relapsing fever (RF) Borrelia. However, RF Borrelia cause severe disease including recurring febrile episodes, nausea, vomiting, and miscarriage, and are often misdiagnosed due to limited awareness. Unlike ixodid ticks, Ornithodoros species exhibit a complex life-cycle and reproductive biology, including autogeny (egg-laying without a blood meal) and multiple gonotrophic cycles. These traits enable the rapid establishment of endemic pathogen foci. However, major knowledge gaps include a poor understanding of infection prevalence in ticks, transovarial transmission (ToT) dynamics, and the molecular mechanisms driving ToT. Our long-term goal is to elucidate the biological and genetic mechanisms that facilitate the maintenance of pathogens in Acari. The rationale and significance of this application is that by understanding the transmission cycle of Borrelia turicatae in field collected tick populations, we can predict disease emergence, persistence, and identify targets to neutralize Acari-borne pathogens. Toward this, we implemented extensive fieldwork across the U.S. and Mexico and assembled the most diverse collection of naturally infected Ornithodoros turicata from densely populated environments. Our findings revealed a broader geography for O. turicata than previously considered, and that these ticks can vertically transmit B. turicatae by autogenous reproduction. Interestingly, we also identified a unique B. turicatae isolate that transmits via tick bite but lacks vertical transmission capability, providing a unique opportunity to delineate the genetic basis of ToT. Our central hypothesis is that specific B. turicatae genotypes are associated with a ToT phenotype in naturally infected O. turicata ticks. To test this hypothesis, we propose two specific aims. Aim 1 will investigate ToT and filial infection rates in O. turicata naturally infected with B. turicatae. Using molecular detection and animal models, we will isolate novel strains and quantify ToT across reproductive cycles. This will clarify how B. turicatae is maintained in nature and inform public health strategies for managing this pathogen. Aim 2 will identify B. turicatae genotypes associated with ToT through comparative genomics and transcriptomics. Leveraging our in- house genomic infrastructure, we will analyze chromosomal and plasmid content to pinpoint genetic elements linked to ToT. Transcriptomic profiling will further refine candidate genes by identifying those up-regulated in the tick versus mammalian hosts. Innovation of this study lies in the integration of field ecology, pathogen isolation, and advanced genomics to identify genetic candidates associated with a ToT phenotype. With our newly reported O. turicata genome and B. turicatae isolates that will be generated in this application, we envision using this model to define the molecular mechanisms driving ToT of Acari-borne pathogens.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2026 ( Subtotal = $200,625 )
2026	2026	BAYLOR COLLEGE OF MEDICINE	1 BAYLOR PLZ	HOUSTON	TX	77030	HARRIS	USA	Allergy and Infectious Diseases Research	000	1	5/7/2026	NEW	$200,625
														Subtotal = $200,625

Grand Total All Awards = $200,625

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Unraveling vector ecology and genomic drivers of vertical transmission: Defining relapsing fever Borrelia persistence in populations of the under-studied argasid tick, Ornithodoros turicata

Award Number: R21AI191624

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 05/05/2026

PERIOD OF PERFORMANCE END DATE: 04/30/2028

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