Investigating the Role of the EMT Pathway on HCMV Infection in Epithelial Cells

Human cytomegalovirus (HCMV) is a highly prevalent pathogen that persists life-long in human hosts. HCMV exhibits broad cellular tropism, and is detected within many relevant physiologic sites, such as the mammary gland, salivary gland, kidney, and prostatic epithelium. The mechanism of viral persistence, particularly within epithelial cells, at these sites remains unclear. To better understand HCMV infection in epithelial cells, we comparatively analyzed patterns of HCMV infection across epithelial cell lines. To that end, this research study demonstrates that i) epithelial cells exhibit a restrictive pattern of HCMV infection, and ii) epithelial-to-mesenchymal transition (EMT) pathway can modulate the outcome of HCMV infection in epithelial cells. First, we demonstrated that ARPE-19 adult retinal pigmented epithelial cells, which are widely used as an epithelial culture model for HCMV infection studies, resemble mesenchymal rather than epithelial cells. Experimental infection studies of ARPE-19 cells and strongly epithelial cells lines unveiled that the epithelial-mesenchymal axis strongly influences permissivity to HCMV infection. Cellular mesenchymal state correlated with permissive HCMV infection, while the epithelial cell state correlated with restrictive infection. We found that MCF10A cells restricted infection at viral entry and viral late protein synthesis. Subsequently, we discovered that EMT-induction in epithelial cells, which transdifferentiated cells into a mesenchymal state, restored permissive infection. Overall, this thesis demonstrates that the outcomes of HCMV biosynthesis is sensitive to EMT. These findings may provide insights into mechanisms of viral persistence in epithelial cells at important physiological sites in vivo.