Expression of the major virulence genes of the bacterium Helicobacter pylori following adherence to human gastric cells
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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| Title |
Expression of the major virulence genes of the bacterium
Helicobacter pylori following adherence to human gastric cells
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| Creator |
Raghwan, Raghwan
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| Subject |
Infectious Diseases and Immunology
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| Description |
Helicobacter pylori, a gram-negative bacterium, colonizes the human stomach in a majority of
the world’s population. The major virulence factors of H. pylori, CagA, VacA are thought to be
associated with chronic inflammation and disease and BabA is necessary for adherence of the
bacterium to host cells. These virulence factors have been extensively studied but the regulation
of expression of these virulence genes in H. pylori remains poorly understood. In this study, H.
pylori was allowed to adhere to a gastric epithelial cell line (AGS) and expression of the
virulence genes was examined in the adhered H. pylori by quantitative RT-PCR. Adherence of
H. pylori to the gastric epithelial cell line AGS, strongly induces expression of the major
virulence genes in H. pylori (cagA, vacA and babA). The induction was dependent on the iron
sensing transcription factor Fur which acts as a global regulator in H. pylori. The induction of
these virulence factors in the AGS cell-adhered H. pylori Δfur mutant strain was consistently
lower than in the adhered parent strain. However expression of the genes was similar between
the wild type and Δfur mutant strains in the un-adhered state, suggesting that Fur has a role in the
upregulation of cagA, vacA and babA expression specifically in host cell adhered H. pylori. The
Δfur deletion mutant in H. pylori was constructed by splicing by overlap extension (SOE) PCR
and allelic exchange method. Furthermore it has been demonstrated that, iron-cofactored Fur
functions as a transcriptional activator of cagA and vacA in host cell adhered H. pylori.
Consistent with these results, microscopic observations revealed that infection of AGS cells with
H. pylori Δfur mutant strain produced much less damage as compared to that produced by the
wild type H. pylori strain. Taken together, these results suggest that cagA, vacA and babA genes
are upregulated in H. pylori specifically by host cell contact and Fur has a role in the
upregulation.
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| Date |
2014-03-03
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| Type |
Thesis
NonPeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/2107/1/RAGHWAN_THESIS.pdf
Raghwan, Raghwan (2014) Expression of the major virulence genes of the bacterium Helicobacter pylori following adherence to human gastric cells. PhD thesis, CU. |
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| Relation |
http://www.eprints.iicb.res.in/2107/
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