Mechanisms of norovirus entry - host cell interaction in vitro and in vivo
Noroviruses, members of the Caliciviridae family, primarily infect humans but also infect pigs, cattle and mice. Human noroviruses are the major cause of nonbacterial epidemic gastroenteritis worldwide resulting in substantial morbidity and economic loss. They cause an estimated 23 million cases of gastroenteritis per year in the USA alone and are frequent visitors to cruise ships, hospitals, daycare centers and other places where crowds gather. Due to the explosiveness of the outbreaks and new strains on the rise, these viruses frequently appear in the popular press where they are often called "stomach bugs" or "cruise ship virus."
However, despite the importance for public health, norovirus research has been severely hampered by the lack of a small animal model and in vitro culture system. Therefore, little or no information is available in many areas of norovirus biology and no directed disease prevention and control strategies exist for these viruses. Even knowledge of fundamental issues such as the viral life cycle and interactions with their host is lacking. Such information however is crucial in understanding how noroviruses cause disease and in developing antiviral therapies for these common agents of gastroenteritis.
In contrast to human noroviruses, murine norovirus replicates in cell culture and infects mice. Our recent development of these tools and the reverse genetics system to generate viral mutants provides us with a unique system to address some of the outstanding questions and begin a detailed analysis of different aspects of norovirus biology. Of particular interest to my lab are the early steps (receptor binding, entry) in the viral life cycle because they are major factors in determining species or tissue specificity, virulence and ultimately the outcome of a virus infection. Therefore, a large focus of my lab is on studying early steps in the viral life cycle (mechanisms of viral entry into host cells) and mechanisms governing virus-host interactions in vitro and in vivo. Current areas of study in the lab are aimed at: i) identifying cellular receptors that facilitate infection, ii) delineating molecular determinants in the viral capsid protein required during virus entry into cells, iii) determining how murine norovirus gains access to permissive macrophages and dendritic cells in the intestine.
In addition, we are interested in identifying new antiviral compounds and develop new strategies for norovirus control. We recently identified a small molecule inhibitor of a small subset of cellular deubiquitinases which inhibits murine and human norovirus replication. Ongoing studies focus on understanding the mechanism of action of this compound, while collaborative efforts are underway to develop a related compound with improved drug-like features.
Taube S., Perry, J. W., McGreevy, E., Yetming, K., Perkins, C, Henderson, K., Wobus, C.E. (2012) Murine noroviruses (MNV) bind glycolipid and glycoprotein attachment receptors in a strain-dependent manner. Journal of Virology [Epub ahead of print].
Taube, S., Jiang, M., and Wobus, C.E. (2010) Glycosphingolipids as Receptors for Non-Enveloped Viruses. Viruses 2, 1011-1049.
Perry, J. and Wobus, C. E. (2010) Endocytosis of Murine Norovirus 1 (MNV-1) into murine macrophages is dependent on dynamin II and cholesterol. Journal of Virology 84, 6163-6176.
Taube, S., Rubin, J. R., Katpally, U., Smith, T. S., Kendall, A., Stuckey, J. A., and Wobus, C. E. (2010) High Resolution X-Ray Structure and Functional Analysis of the Murine Norovirus (MNV)-1 Capsid Protein Protruding (P) Domain. Journal of Virology 84, 5695-705 (highlighted as spotlight).
Katpally, U., Voss, N. R., Cavazza, T., Taube, S., Ruben, J. R., Young, V. L., Stuckey, J. A., Ward, V. K., Virgin, H. W. 4th, Wobus, C. E., and Smith, T. J. (2010) High-resolution cryo-electron microscopy structures of MNV-1 and rRHDV reveals marked flexibility in the receptor binding domains. Journal of Virology 84, 5836-41 (highlighted as spotlight).
Perry, J. W., Taube, S., Wobus, C. E. (2009) Murine Norovirus-1 entry into permissive macrophages and dendritic cells is pH-independent. Virus Research 43, 125-9. PMID: 19463729.
Taube, S., Perry, J. W., Yetming, K., Patel, S. P., Auble, H., Shu, L., Nawar, H. F., Lee, C. H., Connell, T. D., Shayman, J. A., Wobus, C. E. (2009) Ganglioside-linked terminal sialic acid moieties on murine macrophages function as attachment receptors for Murine Noroviruses (MNV). Journal of Virology 83, 4092-101. PMID: 19244326.
Thackray, L. B., Wobus, C. E., Chachu, K. A., Liu, B., Alegre, E. R., Henderson, K. S., Kelley, S. T., Virgin, H. W. 4th (2007) Murine noroviruses comprising a single genogroup exhibit biological diversity despite limited sequence divergence. Journal of Virology 81, 10460-10473.
Ward, V. K., McCormick, C. J., Clarke, I. N., Salim, O., Wobus, C. E., Thackray, L. B., Virgin, H. W. 4th, Lambden, P. R. (2007) Recovery of infectious murine norovirus using pol II-driven expression of full-length cDNA. PNAS 104, 11050-11055.
Wobus, C. E., Thackray, L. B., Virgin, H. W. 4th (2006) Murine norovirus: a model system to study norovirus biology and pathogenesis. Journal of Virology 80, 5104-12.
Wobus, C. E., Karst S. M., Thackray, L. B., Chang, K.-O., Sosnovstev S., Belliot, G., Krug, A., Mackenzie, J. M., Green., K. Y., Virgin, H. W. (2004) Replication of a norovirus in culture reveals a tropism for dendritic cells and macrophages. PLOS Biology 2. e432.
Karst S. M.*, Wobus, C. E.*, Lay, M., Davidson, J., Virgin, H. W. (2003) STAT-1 dependent innate immunity to a Norwalk-like virus. Science 299, 1575-1578.