Date of Award

4-14-2009

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

First Advisor

Barbara R. Baumstark - Committee Chair

Second Advisor

Phang C. Tai - Committee Member

Third Advisor

Roberta Attanasio - Committee Member

Fourth Advisor

Zehava Eichenbaum - Committee Member

Abstract

B. henselae, B. bacilliformis and B. quintana are capable of causing vasoproliferative diseases in humans by modulating apoptosis and proliferation of endothelial cells. Bartonella clarridgeiae, a close relative of the pathogenic Bartonellae, has been implicated in human disease but has not yet been isolated from a human patient. Both B. bacilliformis and B. clarridgeiae have flagella and a flagellar type 3 secretion system, while B. henselae and B. quintana do not. We created 2 non-motile mutants of B. clarridgeiae by interrupting the flagellin gene, flaA, or the flagellar motor genes, motBC. We investigated whether B. clarridgeiae could invade human endothelial cells (HMECs) and if functional flagella were important for invasion. The non-motile mutants and the wild-type strain were capable of entering HMECs in vitro. The flaA mutant was deficient in attachment, but the HMECs in culture with the flaA mutant demonstrated increased proliferation. The motBC mutant showed enhanced invasion. Differential secretion of proteins was revealed by 2-D electrophoresis and MALDI-TOF analysis of secretomes from the co-cultures compared to uninfected HMECs. HMECS infected with wild-type B. clarridgeiae secreted proteins indicative of proliferation. The flaA mutant induced the secretion of proteins involved in cytoskeletal rearrangement, cell migration, and proliferation. The motBC-infected HMECs showed signs of hypoxia. The co-chaperonin GroES was found in higher concentration in the supernatant of the hyper-invasive motBC strain/HMEC co-culture than the wild-type co-culture and was found at a very low concentration in the flaA culture supernatant. Cross-talk between secretion systems is suggested.

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Biology Commons

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