Date Thesis Awarded

12-2017

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Mark H. Forsyth

Committee Member

Beverly Sher

Committee Member

Helen Murphy

Committee Member

Aiko Kitamura

Abstract

Persistent infection by Helicobacter pylori, a gram-negative bacterium, is associated with gastric cancer. The outer membrane protein of H. pylori OipA has been identified as a virulence factor that induces inflammation and facilitates adhesion to epithelial cells by some studies. Our lab has determined that two of our collections of eight Asian strains of H. pylori possess a second copy of oipA, a condition that is not found among European, African or other western strains of H. pylori. The potential significance of this observation arises from the fact that the prevalence of gastric cancer is much higher in Asia than that of the west. We hypothesized that the frequent merodiploid nature (two gene copies in an otherwise haploid genome) of oipA among Asian H. pylori strains may lead to increased induction of the pro-inflammatory cytokine IL-8 and translocation of the effector protein CagA into epithelial cells. Such increase in virulence of Asian H. pylori strains may partially explain the high prevalence of gastric cancer in Asia. However, our results indicate that knocking out each oipA allele individually or ablating both alleles in a single mutant has no effect on IL-8 secretion by AGS cells, adherence ability to AGS cells and CagA translocation of H. pylori strain 98-46. However, our results of the mRNA levels of oipA in our mutant collection indicate transcript levels vary among the mutants.

Available for download on Wednesday, December 12, 2018

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