A Metagenomic Study of The Tick Midgut

<strong>A Metagenomic Study of the Tick Midgut<br></strong> Daniel Yuan, B.S.<br> Supervisory Professor : Steven J. Norris, Ph.D.<br> Southern tick–associated rash illness (STARI) or Master’s disease is a Lyme-like illness that occurs following bites by <em>Amblyomma americanum</em>, the lone-star tick. Clinical symptoms include a bull’s eye rash similar to the erythema migrans lesions of Lyme disease, as well as fever and joint pains. Lyme disease is caused by <em>Borrelia burgdorferi</em> and related spirochetes. However, <em>B. burgdorferi</em> has not been detected in STARI patients, or in ticks in the South Central U.S. The causative agent of STARI has not been identified, although it was once thought to be caused by another <em>Borrelia</em> species, <em>Borrelia lonestari</em>. Furthermore, while adult <em>A. americanum </em>have up to a 5.6% <em>Borrelia lonestari</em> infection rate, the prevalence of all Borrelia species in Texas ticks as a whole is not known. Previous studies indicate that 6%-30% of Northern <em>Ixodes scapularis</em> ticks are infected by <em>Borrelia burgdorferi</em> while only 10% of Northern <em>A. americanum</em> and <em>I. scapularis</em> ticks are infected by <em>Borrelia</em> species. The first specific aim of this project was to determine the bacterial community that inhabits the midgut of Texas and Northeastern ticks by using high throughput metagenomic sequencing to sequence bacterial 16S rDNA. Through the use of massively parallel 454 sequencing, we were able to individually sequence hundreds of thousands of 16S rDNA regions of the bacterial flora from 133 ticks from the New York, Missouri and Texas. The presence of previously confirmed endosymbionts, specifically the <em>Rickettsia</em> spp. and <em>Coxiella</em> spp., that are commonly found in ticks were confirmed, as well as some highly prevalent genera that were previously undocumented. Furthermore, multiple pathogenic genera sequences were often found in the same tick, suggesting the possibility of co-infection of multiple pathogenic species. The second specific aim was to use <em>Borrelia</em> specific primers to screen 344 individual ticks from Missouri, Texas and the Northeast to determine the prevalence of <em>Borrelia</em> species in ticks. To screen for <em>Borrelia</em> species, two housekeeping genes, <em>uvrA</em> and <em>recG</em>, were selected as well as the 16S-23S rDNA intergenic spacer. Ticks from Missouri, Texas and New York were screened. None of the Missouri or Texas ticks tested positive for Borrelia spp. The rate of <em>I. scapularis</em> infection by <em>B.burgdorferi</em> is dependent on tick feeding activity as well as reservoir availability. <em>B. burgdorferi</em> is endemic in the Northeast, sometimes reported as highly present in over 50% of all <em>I. scapularis</em> ticks. 11.6% of all New York ticks were positive for a species of Borrelia, however only 6.9% of all New York ticks were positive for <em>B. burgdorferi</em>. Despite being significantly lower than 50%, the results still fall in line with previous reports of about the prevalence of <em>B. burgdorferi</em>. 1.5% of all Texas ticks were positive for a <em>Borrelia</em> species, specifically <em>B. lonestari</em>. While this study was unable to identify the causative agent for STARI, 454 sequencing was able to provide a tremendous insight into the bacterial flora and possible pathogenic species of both the <em>I. scapularis</em> and the <em>A. americanum</em> tick.

Name thesis:degree_name

Masters of Science (MS)

Level thesis:degree_level

Thesis (MS)

Year dc:date.available

2010

Author dc:creator

• Yuan, Daniel T

Contributors dc:contributor

• Steven J. Norris, Ph.D.
• George E. Fox, Ph.D.
• Angel M. Paredes, Ph.D.

• metagenomic
• ticks
• STARI
• ixodes scapularis
• ambylomma americanum
• Biology
• Laboratory and Basic Science Research
• Pathogenic Microbiology

Repository record dc:identifier

https://digitalcommons.library.tmc.edu/utgsbs_dissertations/85

OAI identifier oai:identifier

oai:digitalcommons.library.tmc.edu:utgsbs_dissertations-1097