Comparative Whole-genome and Phenotype Analyses of Virulence Factors and Lethality in Nematode Challenge Assay among Aeromonas isolates

<p>Aeromonads are bacteria found globally in fresh and brackish waters, with some species causing water-borne diseases vertebrate hosts such as diarrhea and wound-infections in humans and motile <em>Aeromonas</em> septicemia in fish. Although many virulence factors have been described, determining which factors are most important in pathogenesis is ongoing. To examine this further, the genomes of five <em>Aeromonas</em> strains isolated from various animals were sequenced and annotated in this study. Each isolate was further characterized using comparative genomic analyses and testing for production of selected virulence factors. Although previously identified as <em>Aeromonas hydrophila</em>, modern genotypic approaches including multilocus sequence typing and average nucleotide identity were used to determine identity. Four of five were confirmed to be <em>A. hydrophila</em>, but one isolate was identified as <em>A. salmonicida</em>. Virulence and antibiotic resistance genes in the five isolates were identified and compared to the curated genomes of forty-one other <em>Aeromonas</em> isolates. The distribution of virulence and antibiotic resistance genes among the 46 isolates was mapped using several bioinformatic tools. Isolates with similar virulence factor and antibiotic resistance genetic markers tended to originate from similar hosts or the environment, indicating common selective pressure. Challenge of <em>Caenorhabditis elegans </em>with different <em>Aeromonas</em> strains resulted in varying degrees of lethality as measured by nematode survival, and supported the existence of pathotypes; however, no single common virulence factors was found to explain the difference between highly virulent strains and those significantly less virulent. The results indicated that 1) a primary virulence factor responsible for the high degree of virulence remains unknown, or 2) virulence is the result of varying combinations of multiple factors, or 3) a mixed infection of pathotypes is needed to enable low virulent strains to be virulent.</p>

Name thesis:degree_name

Master of Science in Integrative Biology (MSIB)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2020

Author dc:creator

• Kim, Pyeongsug

Contributors dc:contributor

• Tsai-Tien Tseng Ph.D.
• Martin L. Hudson Ph.D.

• Aeromonas hydrophila
• Comparative genomics
• Virulence factors
• Antibiotic resistance
• Caenorhabditis elegans
• Bioinformatics
• Biology
• Environmental Public Health
• Epidemiology
• Integrative Biology
• Public Health

Repository record dc:identifier

https://digitalcommons.kennesaw.edu/integrbiol_etd/50

OAI identifier oai:identifier

oai:digitalcommons.kennesaw.edu:integrbiol_etd-1053