Defense Date
12-3-2024
Document Type
Capstone
Degree Type
Master of Science
Degree Name
Biological Sciences
First Advisor
Julie Torruellas Garcia, Ph.D.
Second Advisor
Katie Crump, Ph.D
Third Advisor
Navi Gill, Ph.D
Keywords
Type Three Secretion Systems, Yersinia pestis, Bacteriophage, Phage Therapy, Bacterial Pathogenesis, Phylogeny, Portal Proteins, Terminase Large Subunits, Tail Fibers
Abstract
Yersinia pestis, the causative agent of the plague, has become increasingly resistant to many antibiotics; therefore, alternatives such as phage therapy are necessary. Phage therapy uses combinations of bacteriophages or phages, which are viruses that only infect bacteria. However, phages—especially Y. pestis phages —are severely understudied. Thus, this research has sought to specifically isolate a phage from soil that infects Y. pestis. There were 146 samples that were collected from across the US, focusing on those with reported cases of plague. These samples were enriched with Y. pestis to maximize the amount of potential phage that target Y. pestis. Afterward, spot tests were completed at both 26°C and 37°C, with the former being the optimal temperature for Y. pestis growth and the latter being the temperature at which the type three secretion system, a virulence factor, is expressed to detect any Y. pestis phages in those samples. One sample from Oklahoma, referred to as ‘FFP,’ yielded a positive result at both temperatures. FFP was isolated through a series of plaque assays. The concentration of FFP was amplified for further identification and characterization. The phylogenetic relationships between the known Y. pestis phages were also investigated using the portal protein and terminase large subunit sequences of 31 phages that infect Y. pestis. Additionally, sequence variation and percent identity of the tail fibers were calculated, which provides insight regarding host range specificity and receptor binding. Better understanding phage diversity and relatedness can assist in creating better combinations of phages for phage therapy.
NSUWorks Citation
Jacqueline Chavez. 2024. An In-Depth Investigation into Yersinia pestis Phages: Isolating a Yersinia pestis Phage from Soil and Constructing a Comprehensive Phylogenetic Analysis of Known Yersinia pestis Phages. Capstone. Nova Southeastern University. Retrieved from NSUWorks, . (206)
https://nsuworks.nova.edu/hcas_etd_all/206.