A fundamental issue in virology is understanding the molecular and cellular events, which underlie pathogenesis and lead to disease. Defining these events is essential for the rational development of anti-viral strategies, and provides insights into fundamental processes of gene regulation and cell biology. Plant viruses must cross the barrier of the plant cell wall to move cell-to-cell and invade the host to cause disease. To do this, they encode a novel class of so-called `movement proteins`, which are major determinants of virus host range and disease potential. My lab uses the model plant Arabidopsis thaliana and two model plant viruses –– the DNA geminivirus Cabbage leaf curl virus (CaLCuV), and the RNA tobamovirus Tobacco mosaic virus (TMV). Our goal is to understand how movement proteins transport virus genomes within and between cells, and to use these proteins as models to identify the cellular transport pathways that regulate cell-cell communication in plants. Using the approaches of molecular genetics, biochemistry, cell biology and genomics, our research has established the current model for how the two geminivirus movement proteins, NSP and MP, cooperate to transport the viral DNA genome from its site of replication in the nucleus to, and across, the cell wall: NSP (Nuclear Shuttle Protein) is needed to import the virus genome into the nucleus for replication and export newly replicated virus genomes back to the cytoplasm; MP (cell-to-cell Movement Protein) traps NSP-genome complexes in the cytoplasm and directs these to the cell wall for movement into adjacent uninfected cells to propagate the infection. Our investigation of the CaLCuV and TMV movement proteins has also led us to discover a family of proteins in plants, which were thought to only be present in the animal nervous system: synaptotagmins. Our current studies of these plant synaptotagmins have identified an endosome recycling pathway, which acts to ferry movement proteins and their virus genome cargos to plasmodesmata (transwall pores) for transport across the cell wall. Our findings also suggest that synaptotagmins play key roles in regulating both the cell-to-cell spread of most, if not all, plant viruses and cell-cell communication in plant development.

My goals in teaching are to emphasize basic principles and concepts about how viruses interact with their hosts and cause disease, and to convey my enthusiasm for viruses: they are, without doubt, fabulous! My challenges as a teacher are to make my students think about things they never thought about before, and to have them see that they could be doing research. BIOMI 409 / VETMI 409 "Principles of Virology" is a unique course. It covers the principles of virology, focused mainly on animal viruses. However, it also includes plant viruses and bacteriophage, taking a unique integrative approach and, in particular, emphasizing virus-host cell interactions and common themes between different viral families that infect animals, plants and bacteria. BIOPL 652.1/PLPA 662.1 "Plant Responses to Pathogen Attack" emphasizes the principle concepts about how plants defend themselves against infection by viruses, bacteria and fungi.