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2013 Scientific Report

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VARI |

VARI | 2013 The death of one hypothesis, however, gives life to new ideas. After the initial infection of a cold sore subsides, herpes simplex virus establishes a life-long latent infection in sensory neurons. In the latent state, the viral genome is essentially quiet; very few viral genes are expressed. Moreover, the viral genome becomes packaged in chromatin much like the silent genes of the host cell. So our new hypothesis is that the coactivators recruited by VP16 are required to reactivate the viral genes from the latent or quiescent state. We now have evidence that VP16 is likely the very first viral gene to be expressed during the reactivation process. We want to test whether the ability of VP16 to recruit coactivators is essential for subsequent events of reactivation. We will test this hypothesis both in quiescent infections in cultured cells and in animal models with genuinely latent herpesvirus infections. Regulating the regulatory proteins: posttranslational modifications of VP16 The activity of a given protein is not only dependent on being expressed at the right time, but also on chemical modifications of its amino acids and on its interactions with other proteins. Proteins can be posttranslationally modified by adding chemical groups including phosphates, sugars, methyl or acetyl groups, lipids, or small proteins such as ubiquitin. Each of these modifications might affect the protein in different ways, including how the protein folds, how it interacts with other proteins, and how stable it remains in the cell. We know that VP16 can be phosphorylated, and we have already defined several sites within the VP16 protein where this happens. We are now testing whether these modifications matter for how VP16 functions, either as a transcriptional activator protein or as a structural protein of the HSV-1 virion. In some experiments, we create mutations that either prevent phosphorylation or that introduce an amino acid that mimics phosphorylation, and then we test the effects of these mutations on VP16 functions. In other experiments, we inhibit the enzymes that apply the modifications (for phosphorylation, these enzymes are known as protein kinases). We expect that this work will lead to new ideas about ways that we can selectively inhibit modification of VP16 using small-molecule drugs, and thereby prevent or shorten the infection process by HSV. Recent Publications Danaher, Robert J., Ross K. Cook, Chunmei Wang, Steven J. Triezenberg, Robert J. Jacob, and Craig S. Miller. In press. C-terminal trans-activation sub-region of VP-16 is uniquely required for forskolin-induced herpes simplex virus type 1 reactivation from quiescently infected-PC12 cells but not for replication in neuronally differentiated-PC12 cells. Journal of Neurovirology. Silva, Lindsey, Hyung Suk Oh, Lynne Chang, Zhipeng Yan, Steven J. Triezenberg, and David M. Knipe. 2012. Roles of the nuclear lamina in stable nuclear association and assembly of a herpesviral transactivator complex on viral immediate-early genes. mBio 3(1): e00300–11. Sawtell, Nancy M., Steven J. Triezenberg, and Richard L. Thompson. 2011. VP16 serine 375 is a critical determinant of herpes simplex virus exit from latency in vivo. Journal of Neurovirology 17(6): 546–551. 53

Jeremy M. Van Raamsdonk, Ph.D. Laboratory of Aging and Neurodegenerative Disease Jeremy Van Raamsdonk received a B.Sc. (Honours) in biochemistry from the University of British Columbia in 1993. After completing an M.Sc. in medical science at McMaster University in 1999, he returned to the University of British Columbia to complete a Ph.D. in medical genetics in 2005. Subsequently, he became a postdoctoral fellow in the Department of Biology at McGill University until joining the Van Andel Research Institute as an Assistant Professor in 2012. Staff Kim Cousineau, B.S. Keith Dufendach, B.S. Megan Senchuk, Ph.D. 54

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