Date of Award

12-2008

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Microbiology

Advisor

Carol H. Kim

Second Committee Member

John T. Singer

Third Committee Member

Charles E. Moody

Abstract

Cystic Fibrosis (CF) is a common lethal genetic disease caused by a recessive mutation in the cystic fibrosis transmembrane conductance regulator (CFTR). Among other manifestations, the human disease is characterized by prevalent and chronic lung infections with the bacterium Pseudomonas aeruginosa, but to this day, the reason for susceptibility of CF patients to that particular infection remains elusive. P. aeruginosa is a Gram-negative, biofilm producing opportunistic human pathogen that is of serious concern in nosocomial burn-wound and urinary tract infections. It exhibits natural broad-spectrum antibiotic resistance and can survive in a multitude of temperatures and environments including diesel and jet fuel. To date, no zebrafish model has been established to study the CFTR gene mutation, P. aeruginosa infection, or the mutation’s effects upon infection with the bacteria. This study seeks to first characterize P. aeruginosa infection in zebrafish embryos, and second, to examine the effects of CFTR knockdown on the infection. The results of this investigation indicate that P. aeruginosa infection by injection but not static immersion yields a disseminated infection and that P. aeruginosa is readily phagocytosed by circulating macrophages. We also demonstrate that morphant embryos exhibit a higher bacterial load upon infection, that Il-1ß and TNF-a expression are perturbed in CFTR morphant fish versus control fish upon infection, and that respiratory burst response is significantly higher in morphants. These results parallel those found in CF patients and in CF mouse models. These findings, in addition to the well-known advantages to using zebrafish in scientific research, make the zebrafish embryo an attractive model for future CF research.

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