Delineation of Aeromonas hydrophila Pathotypes by Dectection of Putative Virulence Factors using Polymerase Chain Reaction and Nematode Challenge Assay

<p><em>Aeromonas hydrophila </em>is a Gram-negative, bacterial pathogen of humans and other vertebrates. To delineate pathotypes, the genomes of twenty-eight <em>Aeromonas </em>isolates<em> </em>were screened by PCR to determine the presence of virulence factors including: aerolysin (<em>aerA</em>)<em>, </em>cytotoxic enterotoxin (<em>act</em>), hemolysin (<em>ahh</em><em>1</em>), elastase (<em>ahy</em><em>B</em>), enolase (<em>eno</em>), S-layer protein (<em>ahsA</em>), serine protease (<em>ser), </em>Type IV <em>Aeromonas</em> pilus (<em>tap</em><em>A</em>), lipase (<em>lip</em>), and Type Three Secretion System (T3SS) components (<em>aopB</em>, <em>ascV</em>). Genes for <em>ahh1</em>, <em>lip</em>, <em>ser</em>, and <em>ahyB</em> were present in all 28 strains tested, others genes varied. The <em>tapA </em>gene encoding a type IV pilus was absent in all 28 isolates screened. After the presence or absence of these genes was determined, corresponding activity was determined using phenotypic assays. Analysis of the data defined 11 different pathotypes based on the genotypic and phenotypic profiles with the largest cluster being <em>ahh1</em>⁺, <em>ahyB</em>⁺, <em>lip</em>⁺, <em>ser</em>⁺, <em>act</em>⁺, <em>aerA</em>⁺, <em>eno</em>^-, <em>aopB</em>^-, <em>ascV</em>^-, <em>ahs</em>A^-, and <em>tapA</em>^-. Representatives of the pathotype groups were used in a nematode challenge assay and a cell culture assay to assess the importance of virulence factors in their pathogenicity and their cytotoxicity, respectively. All <em>Aeromonas </em>strains tested, with the exception of <em>A. hydrophila</em> ML09-119, showed significantly greater lethality compared to the <em>E. coli </em>negative<em> </em>control in the nematode challenge, yet only <em>A. hydrophila</em> 1127 was significantly more lethal than the positive control <em>Pseudomonas aeruginosa</em> PAO1. Variation in lethality between <em>A. hydrophila</em> strains suggests that <em>C. elegans</em> is a suitable model for studying pathogenic mechanisms and elucidating the combination of factors that define highly virulent strains.</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

2015

Author dc:creator

• Metz, John

Contributors dc:contributor

• Dr. Melanie Griffin
• Dr. Martin Hudson

• Aeromonas hydrophila
• Pathotypes
• Cell Culture Assay
• Nematode Challenge Assay
• Motile Aeromonas Septicemia
• Wound infections
• Biology
• Integrative Biology

Repository record dc:identifier

https://digitalcommons.kennesaw.edu/integrbiol_etd/7

OAI identifier oai:identifier

oai:digitalcommons.kennesaw.edu:integrbiol_etd-1005