Date of Award

Summer 8-2015

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)


Biological Sciences

Committee Chair

Shahid Karim

Committee Chair Department

Biological Sciences

Committee Member 2

Yanlin Guo

Committee Member 3

Mohammed Elasri

Committee Member 3 Department

Biological Sciences


Ticks are ectoparasites that attach to their host for many days to weeks, feeding to engorgement and continuing their species life cycle. The mechanisms behind the successful feeding and manipulation of host immune responses have been associated with the secretion of their specialized saliva. Tick saliva includes a variety of modulatory molecules that must disrupt and counteract defense mechanisms, including a variety of proteases. Reprolysin Metalloproteases, in the Zn2+ dependent family, is secreted as a proenzyme and is shown to have proteolytic activity, degrading fibrinogen and gelatinase activity, as well as disturbing homeostasis12. Previous work with the Amblyomma americanum sialotranscriptome identified over 40 metalloproteases secreted in the saliva during the ticks’ feeding. A. americanum is a carrier of multiple diseases, including Ehrlichia chaffeensis, the causative agent of Human Monocyte Ehrlichiosis. This experiment consisted of two main goals: the first was to characterize A. americanum Reprolysin Metalloproteases, and the second to gain a better insight into the relationship between this tick and E. chaffeensis, a pathogen very understudied within the tick vector and has proved problematic for animal model studies.