Gerald Alter (Committee Member), Nancy Bigley (Advisor), Nancy Bigley (Committee Member), Barbara Hull (Committee Member)
Master of Science (MS)
The hypothesis of this study is: HSV-1 infection of murine fibroblasts and keratinocytes inhibits expression of MHC class I molecules during first 24 hours of infection. IFN-γ pretreatment of fibroblasts protected the cells from virus-induced inhibition of MHC class I expression, but did not protect keratinocytes. Herpesviruses are known for their ability to establish persistent infections. Herpesviruses exert many different ways to suppress host defense mechanisms. One such way is by down regulating expression of the major histocompatibility complex I (MHC I) molecules in infected cells. Epidermal cells such as keratinocytes are the major sites for herpes simplex virus type 1 (HSV-1) replication both in active primary and recurring herpes infection. In this study, murine keratinocyte cell lines (HEL-30 and PAM-212) were shown to be refractory to IFN-γ induction of an MHC class I expression to HSV-1 infection, while IFN-γ did induce MHC class I expression in murine fibroblast cell lines (L929 and A2R1). In the current study, using Image J analyses of immunocytochemical data, MHC class I expression decreased at 6, 12, and 24 hours after infection of L929 and A2R1 fibroblasts (p< 0.001) with HSV-1 infection. The effect of IFN-γ on expression of MHC I molecules was evaluated in HSV-1-infected murine keratinocytes and fibroblasts at 24 hours after infection. In other studies, IFN-γ was found to protect the murine fibroblast cell line, L929 from the cytopathic effect of HSV-1 but was unable to protect murine keratinocyte cell lines (HEL-30 and PAM-212) from HSV-1 induced cytopathic effects (Frey et al., 2009). Immunofluorescent staining for expression of MHC class I molecules in IFN-γ treated and HSV-1 infected cells was performed using immunocytochemistry and flow cytometry. Only the fibroblast cell lines could be examined by both methods. Significant increases (p < 0.001) in expression of MHC class I molecules were seen in both HSV-1 infected fibroblast cell lines after treatment with IFN-γ using both immunocytochemistry and flow cytometry. Since keratinocytes grow in clusters, immunocytochemistry was not used to evaluate their expression of the MHC class I molecules in HSV-1-infected and IFN-γ treated cells. Keratinocytes could be gently removed from the culture using cell stripper solution, and were then examined by flow cytometry for expression of MHC class I molecules. In both keratinocyte cell lines, significant decreases in expression levels of MHC class I molecules over baseline levels (p<0.001) were observed after HSV-1 infection and IFN-γ treatment. In the current study, HSV-1 infection of murine fibroblasts and keratinocytes inhibited expression of MHC class I molecules during first 24 hours of infection. IFN-γ pretreatment of fibroblasts protected them from virus-induced inhibition of MHC class I expression, but did not protect keratinocytes. The refractoriness of keratinocytes to IFN-γ might be due to the expression of suppressor of cytokine synthesis-1 (SOCS-1) during HSV-1 infection as observed by the Frey et al., (2009).
Department or Program
Microbiology and Immunology
Year Degree Awarded
Copyright 2012, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.