Significance H. pylori is a cause of peptic ulcer disease and gastric cancer. Only primates are naturally infected with H. pylori, and so the rhesus monkey is an optimal model. The green fluorescent protein (GFP) is a reporter that can be used to observe in vivo gene expression. Objectives The purpose of this study was to (1) determine if a plasmid bearing the gene for GFP could be expressed in H. pylori; and (2) determine if an H. pylori strain expressing GFP could be maintained in the monkey stomach. Results A chimeric plasmid was constructed. The gene for GFP was inserted in the plasmid under the control of a promoter that in wild-type H. pylori is responsible for driving expression of the essential gene, urease. The plasmid also contained a gene for resistance to the antibiotic kanamycin, to which H. pylori is normally sensitive. A rhesus-derived strain of H. pylori was transformed with the plasmid and transformants were selected that were resistant to kanamycin, and were documented to be H. pylori. Examination of this strain under fluorescence microscopy showed that it fluoresced bright green, indicating that the gene for GFP was expressed constitutively. This strain was inoculated into two rhesus monkeys every other day for 3 days. Endoscopy with culture of gastric biopsy at 2 weeks was negative for H pylori in both animals, but was positive at 4 weeks and at 8 weeks post inoculation in 1 animal. The strain was confirmed to be the GFP expressing H. pylori by means of g enotypic analysis and fluorescent microscopy. Future Directions This plasmid gives us the opportunity to examine in vivo regulation of expression of genes in H. pylori. We will use fluorescence microscopy of tissue from animals infected with strains bearing a plasmid that has the GFP gene under control of a promoter of interest to study in vivo expression. KEY WORDS peptic ulcer disease, gastritis, gastric cancer FUNDING Various
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