Date of Graduation


Document Type


Degree Level



Poultry Science


Voth, Daniel E

Committee Member/Reader

Erf, Gisela F

Committee Member/Second Reader

Anthony, Nicholas B.


The intracellular bacterial agent of Q fever, Coxiella burnetii, replicates within a phagolysosome-like parasitophorous vacuole (PV) in human macrophages and delivers effector proteins to the host cytosol via a Dot/Icm type IV secretion system (T4SS). T4SS effectors are critical for PV formation and prevention of host cell death that allows sufficient time for bacterial replication. Recruitment of ubiquitin-related components to the C. burnetii PV is also predicted to be involved in PV formation and bacterial replication and is likely controlled by effector proteins. In this study, we assessed the role of the Dot/Icm T4SS in regulating ubiquitination by comparing subcellular localization of ubiquitinated proteins between cells infected with wild type C. burnetii and a mutant that lacks a functional T4SS. Fluorescence microscopy showed ubiquitinated proteins surrounding wild type C. burnetii PV but not phagosomes harboring T4SS-defective organisms. Immunoblot analysis showed altered ubiquitinated protein profiles throughout infection, suggesting C. burnetii impacts post-translational modification of host cell and/or bacterial proteins. Future studies will determine how T4SS-mediated recruitment of ubiquitinated proteins impacts C. burnetii-host cell interactions and eventual development of disease.


Biology, Cell, Biology, Microbiology, Biology, Zoology