Date of Award
Daniel Nichols, PhD
Erik Hill, PhD
Jessica Cottrell, PhD
Molluscum Contagiosum Virus, MCV, Necroptosis, P-MLKL, MC159
Viruses must overcome the countless obstacles the human immune system deploys to slow and reduce their spread throughout the body. Molluscom Contagiosum Virus (MCV) is a poxvirus that clinically manifests as lesions on the skin. MCV devotes a majority of its genome to code for immune evasion proteins so that host immune system strategies involved in detecting and eliminating viral threats are dampened. MCV genes MC159L and MC160L code for death effector domain containing-proteins responsible for inhibiting and altering signaling of many host viral detection and elimination pathways such as TNF-induced inflammation and apoptosis. Mitigating the effects of TNF likely gives MCV the ability to replicate and infect more cells, thus causing long-term infections of host keratinocytes. To better understand the mechanisms of MCV immune evasion proteins, this study characterized the expression of MC159 and MC160 on TNF-induced necroptosis, a form of cell programmed death. Currently, there are no cell culture models to recapitulate MCV infection in vitro. To study the effects of MC159 and MC160, HEK293T and HT-29 cells were transiently transfected with the MCV immune evasion genes and subjected to various conditions that would mimic immune system activation of cell-mediated death pathways. Necroptosis was induced by treating cells with TNF-α, z-VAD-FMK, and SM-164, and confirmed by detection of P-MLKL, a downstream product of the necroptosis pathway. By comparing levels of P-MLKL in cells transfected with MC159 and MC160 to non-transfected cells, a difference in levels could indicate that these viral proteins are interfering with this pathway. This experiment showed minimal changes in P-MLKL suggesting that MC159 and MC160 do not interfere with or prevent MLKL from being phosphorylated by RIPK3. Using a cell titer glo assay, results indicated that MC159-transfected cells provided significant protection against cell death when necroptosis was induced. Preliminary results from immunoprecipitation assays suggest an interaction between MC159 and MLKL. The working hypothesis is that MC159 interacts with MLKL and can prevent its oligomerization or translocation to the cell membrane.
Gregory, Matthew, "Molluscum Contagiosum Viral Protein MC159 Interferes with Necroptosis Signaling Downstream of P-MLKL in HEK 293T and HT-29 Cells" (2022). Seton Hall University Dissertations and Theses (ETDs). 2967.
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