Date of Award

Spring 5-1-2005

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Advisor

H. Kathleen Dannelly

Second Advisor

James Hughes

Third Advisor

Gary Stuart

Abstract

Helicobacter pylori undergoes significant mutation during chronic infection. The organism adapts to its specific host allowing a selective advantage even after repeated exposure to new competing strains. Genetic drift does not fully explain the ability of some strains to outcompete pre-existing strains or newly introduced strains. The hypothesis behind this research is that H. pylori HPM8 produces a peptide encoded on a plasmid, pHPM8, which has antibacterial activity against other H. pylori strains. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was used to determine the stage of the growth cycle the peptide is being expressed. RT-PCR demonstrated peptide expression throughout the growth cycle. Susceptibility testing analogous to the Kirby Bauer Method was used to determine if H. pylori HPM8 could inhibit the growth of other H. pylori strains. Results indicated H. pylori HPM8 does produce a substance that inhibits the growth of other H. pylori strains. Recombinant DNA techniques were to be used to insert an antibiotic resistance gene and a fluorescent gene into pHPM8 to quantify peptide expression. However Polymerase Chain Reaction (PCR) failed to amplify the kanamycin cassette of pBCa3 for insertion into pHPM8. Biology Workbench was used to search for genes homologous to the operon encoded on pHPM8 that contains the potential antibacterial peptide. Sequence analysis showed that in addition to pHPM8 two more H. pylori plasmids encode this operon. Future research includes isolating the peptide for structural and functional studies.

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