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Access Type
WSU Access
Date of Award
January 2023
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Immunology and Microbiology
First Advisor
Jeffrey H. Withey
Abstract
The human disease cholera, marked by acute, voluminous watery diarrhea, is caused by the gram-negative, aquatic bacterium Vibrio cholerae. The zebrafish (Danio rerio) has quickly become a popular model organism among the scientific community in recent years and provides several advantages over mammalian models to studying the “big picture” of V. cholerae infection. Native to the same regions as endemic cholera, zebrafish have long been associated with V. cholerae and are naturally susceptible to infection and disease, even in the presence of a fully functioning immune system and without modification of the normal microbiota. Therefore, zebrafish serve as a uniquely qualified model for studying the complete V. cholerae infectious cycle, from exposure to colonization to excretion and hypervirulent transmission to a naïve host. As this model is relatively new, several questions surrounding the interaction between V. cholerae and zebrafish remain unanswered. For the first time, this study utilizes transposon sequencing to identify colonization factors required by V. cholerae in the zebrafish intestine. Additionally, this study identifies a long-term colonization phenotype by the pandemic V. cholerae O1 biotype, El Tor. The El Tor genome resembles that of classical but has acquired two unique pathogenicity islands known as Vibrio Seventh Pandemic (VSP) -1 and -2. Preliminary studies demonstrate VSP-2 is required to observe this phenotype, but VSP-1 is not. By creating targeted operon-based knockouts of the VSP-2 island, the operon VC0490-0493 on the 5’-most end of the VSP-2 was identified as essential for enabling prolonged colonization at concentrations comparable to wildtype intestinal load. By identifying the genes required for colonization by environmental and pandemic V. cholerae strains as well as those utilized by the El Tor biotype to colonize a natural host for prolonged periods, we gain insight into how this pathogen may persist in the environment and perpetuate disease.
Recommended Citation
Walton, Madison Grayce, "Identifying Critical Genetic Factors In Pandemic Vibrio Cholerae Colonization Of The Zebrafish Natural Host" (2023). Wayne State University Dissertations. 3850.
https://digitalcommons.wayne.edu/oa_dissertations/3850
