Deciphering the nuclear entry mechanisms of DNA viruses

PROJECT SUMMARY/ABSTRACT Viruses are obligate intracellular parasites that cannot replicate or survive outside of a host. To produce new viral progeny, they must first gain entry into their target host cells where they hijack various cell biological processes to complete their life cycles. The overall goal of my research program is to determine the molecular mechanisms required for successful viral entry and to identify the host-pathogen interactions governing this essential step in infection. In general, viral entry requires receptor binding at the host cell surface, internalization, and subsequent transport of the virus through the endomembrane system towards its site of replication. Most viruses with DNA genomes replicate in the nuclei of infected cells and, consequently, must cross the nuclear envelope to access host DNA replication machinery. How viruses penetrate this physical barrier to enter the nucleus is a major gap in understanding that will be addressed by this research proposal. We are particularly interested in understanding how viruses with oncogenic (cancer-causing) and oncolytic (cancer-treating) potential enter cells to establish infection. Over the next five years, we will investigate the general entry mechanisms of two DNA viruses—the oncogenic Merkel cell polyomavirus (MCPyV) and the oncolytic LuIII parvovirus. Using a combination of molecular biology, biochemistry, and high-resolution microscopy techniques, this R35 proposal will determine (1) how MCPyV and LuIII target to and cross the nuclear membrane, and (2) the host factors that are required for this process. Interestingly, both viruses appear to use non-canonical nucleocytoplasmic transport mechanisms to reach the nucleus. Therefore, these research findings will increase our fundamental understanding of viral nuclear entry mechanisms to advance the diagnosis, treatment, and prevention of virus-associated disease. Moreover, the transport of molecules into and out of the nucleus is often dysregulated in unrelated human disorders, so this work also will provide additional insight into cellular nucleocytoplasmic transport mechanisms that are more broadly relevant to human health. Overall, these studies will lay the foundation for a productive and well-established research program investigating the cellular entry mechanisms of these and other DNA viruses while increasing our understanding of the basic biological pathways with which they interact.