Comparative Analysis of Live, Heat-inactivated, and Electron Beam Inactivated Salmonella Typhimurium Infection in Human Host Cells

Abstract

Salmonella Typhimurium continues to be a leading cause of human gastroenteritis worldwide. This organism is a facultative intracellular pathogen, meaning that it is able grow and reproduce within the host cell it inhabits. S. Typhimurium has the ability to invade and replicate within human intestinal epithelial cells, which in turn causes induced cell death or apoptosis.

The human intestinal epithelial cells, HCT-8, were challenged with live, heat inactivated, and electron beam inactivated S. Typhimurium for various time points. Infected cell monolayers were collected for RNA extractions, and Real-time PCR was performed on the samples to analyze differential gene expression. Genes of the host cell that were expected to be differentially expressed were shortlisted and Real-Time PCR analysis was performed.

Internalized Salmonella within the host cell was unable to be successfully visualized using fluorescent light microscopy. However, differential gene expression for a common transcriptional regulator and inflammatory chemokine were observed to be expressed significantly higher in response to e-beam inactivated Salmonella infection. Genes coding for extracellular and intracellular pattern-recognition receptors of the host cells were shown to be up-regulated in response to e-beam inactivated Salmonella infection at 4 and 24 hours, but were not statistically significant. Additional studies must be conducted to definitively confirm e-beam irradiated Salmonella has the ability to invade human host cells.