Bacteria interact intimately with humans, from “good” bacteria that live in our bodies to “bad” pathogenic bacteria that cause disease. Pathogenic bacteria express virulence genes, which help bacteria invade and attack their host. The ability to control virulence gene expression would help us treat infection more effectively. Several virulence genes in the bacterium Salmonella typhimurium have been observed to be heterogeneously expressed, which means gene expression levels vary among individual bacteria. However, it remains unknown whether this is common to all virulence genes. To look at variation in additional virulence genes, I investigated expression of the genes rpoS and phoP, which regulate virulence and adaptive responses in S. typhimurium. To detect gene expression in real time, I created fluorescent promoter reporters for rpoS, phoP, and their downstream targets katE and pagC. I validated these reporters by exposing cells to the appropriate stimulus and imaging the cells. I observed fluorescent protein expression under the expected conditions, along with heterogeneity in reporter expression. I then infected live macrophages (immune cells that engulf bacteria) with the reporters, and preliminary results suggest that rpoS and katE were primarily activated in a subset of bacteria. I intend to conduct further studies, such as combining the rpoS and phoP reporters in the same cell to examine coregulation of both genes. The findings thus far suggest variation in virulence gene expression in S. typhimurium. Further research into the cause behind this variation and its effect on S. typhimurium could provide insight into infection by this pathogen.

Last modified

• 06/30/2021

Creator

• Chen, July

DOI

• https://doi.org/10.21985/n2-2msn-y735

Keyword

• Bacteria
• Salmonella typhimurium
• Microbiology
• Virulence

Date created

• 2021

Resource type

• Conference Proceeding

Rights statement

• In Copyright