Department or Program

Biology

Abstract

Lyme disease is the most important zoonosis in the northern hemisphere, and the causative agent, Borrelia burgdorferi sensu lato, circulates between Ixodes tick vectors and a large range of vertebrate hosts, including songbirds. Songbirds are particularly interesting reservoirs because they have the potential to rapidly expand the spatial distribution of B. burgdorferi, and species differ in their ability to transmit B. burgdorferi to uninfected ticks. The sensitivity of B. burgdorferi to serum from eight different songbird species was analyzed by incubating B. burgdorferi with the serum of wild-caught birds for one and four hours and determining the number of live and dead Borrelia using BacLight stain and fluorescence microscopy. In a follow-up experiment, complement pathway activation was assessed by chelating serum with MgEGTA (ethylene glycol-bis(2-aminoethylether)-N,N,N’,N’-tetraacetic acid and MgCl2) to selectively block the classical complement pathway, EDTA (ethylenediaminetetraacetic acid) to block both the classical and alternative complement pathways, and by heat inactivating serum to block both pathways. Reservoir-incompetent gray catbirds (Dumetella carolinensis) killed 28% more B. burgdorferi than reservoir-competent American robins (Turdus migratorius) at four hours (F2, 52=8.56, pB. burgdorferi than normal serum or serum treated with MgEGTA or heat inactivated (F4, 70=4.51, p=0.003), which contradicts previous findings that the alternative pathway is responsible for borreliacidal activity, but the results of this experiment were somewhat equivocal. It is hypothesized that differences in borreliacidal abilities of different hosts such as robins and catbirds are due to B. burgdorferi’s ability to evade complement-mediated lysis in certain hosts. Studying the processes of pathogen circulation in natural host populations is required for assessing their relevance to ecosystem dynamics and public health.

Level of Access

Restricted: Embargoed [Open Access After Expiration]

First Advisor

Dearborn, Donald

Date of Graduation

5-2013

Degree Name

Bachelor of Science

Number of Pages

68

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