Honors College Theses

Publication Date

2025

Major

Biology (B.S.B.)

Release Option

Restricted to Georgia Southern

Faculty Mentor

Dr. Lisa D. Brown

Abstract

Cat fleas (Ctenocephalides felis) are hematophagous ectoparasites and vectors of several zoonotic bacterial pathogens, such as murine typhus, cat scratch disease, and bubonic plague. The three general methods of pathogen transmission include invasion of salivary glands, regurgitation of bloodmeals, or contaminated fecal pellets. Focusing on saliva transmission, it has been noted that after a flea ingests an infected bloodmeal, pathogens have been shown to traverse the flea gut epithelial barrier and invade the salivary glands. During a flea bite, the salivary glands can then secrete the pathogen into the bite site, which results in pathogen transmission. However, the mechanism(s) by which pathogens escape from the flea gut barrier and enter the salivary glands remain unclear. This project aimed to determine if mechanical damage during blood feeding compromises the integrity of the flea midgut epithelia. Given that the flea midgut is rich in collagen, damage to collagen was quantified using a fluorescent collagen hybridizing peptide (CHP), which binds to denatured collagen. Midguts were harvested from pooled flea samples at 0, 2, 7, 14, and 21-days post-emergence (dpe) and analyzed for CHP signal intensity. Additionally, a non-absorbable blue food dye was used to visually analyze GI tract permeability after bloodmeal ingestion. Our findings indicate that collagen damage within the midgut varies with age, peaking at 7-dpe. Despite the increases in denatured collagen, there was no detectable leakage of the blue dye into the hemocoel, suggesting that midgut permeability remains functionally intact.

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