Vertical transmission ofBorrelia turicatae(Spirochaetales:Borreliaceae) by autogenously reproducingOrnithodoros turicata(Ixodida: Argasidae) female naturally infected with the spirochetes

Abstract

AbstractOrnithodoros turicatais a vector of relapsing fever (RF) spirochetes in North America and transmitsBorrelia turicataeto a variety of vertebrate hosts. The remarkably long lifespan ofO. turicataand its ability to maintain spirochetes horizontally (between life stages) and vertically to progeny promotes the perpetuation ofB. turicataein nature. Nevertheless, the reproductive biology ofO. turicatais poorly understood. In this report, we collected ticks from a park within a neighborhood of Austin, Texas. They were reared to adulthood and male ticks were individually housed with females. We observed autogenous reproduction by the ticks and further investigated vertical transmission ofB. turicataeby quantifying filial infection rates in a cohort of progeny ticks. These results indicate thatO. turicatatransovarially transmitsB. turicataeduring autogenous reproduction and further signify the tick as a natural reservoir of the spirochetes.ImportancePrevious research has implicatedOrnithodorosticks, includingOrnithodoros turicata, as long-term reservoirs of relapsing fever (RF) spirochetes. Considering the tick’s long lifespan and their efficiency in maintaining and transferring spirochetes within the population, the infection could persist in a given enzootic focus for decades. However, little is known about the relative importance of horizontal and vertical transmission routes in the persistence and evolution of RFBorrelia. Our observations on the reproductive biology ofO. turicatain the absence of vertebrate hosts indicate an additional mechanism by whichB. turicatacan be maintained in the environment. This work establishes the foundation for studyingO. turicatareproduction and spirochete-vector interactions, which will aid in devising control measures forOrnithodorosticks and RF spirochetes.