Structure of a Murine Norovirus NS6 Protease-Product Complex Revealed by Adventitious Crystallisation

Murine noroviruses have emerged as a valuable tool for investigating the molecular basis of infection and pathogenesis of the closely related human noroviruses, which are the major cause of non-bacterial gastroenteritis. The replication of noroviruses relies on the proteolytic processing of a large polyprotein precursor into six non-structural proteins (NS1–2, NS3, NS4, NS5, NS6pro, NS7pol) by the virally-encoded NS6 protease. We report here the crystal structure of MNV NS6pro, which has been determined to a resolution of 1.6 Å. Adventitiously, the crystal contacts are mediated in part by the binding of the C-terminus of NS6pro within the peptide-binding cleft of a neighbouring molecule. This insertion occurs for both molecules in the asymmetric unit of the crystal in a manner that is consistent with physiologically-relevant binding, thereby providing two independent views of a protease-peptide complex. Since the NS6pro C-terminus is formed in vivo by NS6pro processing, these crystal contacts replicate the protease-product complex that is formed immediately following cleavage of the peptide bond at the NS6-NS7 junction. The observed mode of binding of the C-terminal product peptide yields new insights into the structural basis of NS6pro specificity

MDA-5 Recognition of a Murine Norovirus

Noroviruses are important human pathogens responsible for most cases of viral epidemic gastroenteritis worldwide. Murine norovirus-1 (MNV-1) is one of several murine noroviruses isolated from research mouse facilities and has been used as a model of human norovirus infection. MNV-1 infection has been shown to require components of innate and adaptive immunity for clearance; however, the initial host protein that recognizes MNV-1 infection is unknown. Because noroviruses are RNA viruses, we investigated whether MDA5 and TLR3, cellular sensors that recognize dsRNA, are important for the host response to MNV-1. We demonstrate that MDA5−/− dendritic cells(DC) have a defect in cytokine response to MNV-1. In addition, MNV-1 replicates to higher levels in MDA5−/− DCs as well as in MDA5−/− mice in vivo. Interestingly, TLR3−/− DCs do not have a defect in vitro, but TLR3−/− mice have a slight increase in viral titers. This is the first demonstration of an innate immune sensor for norovirus and shows that MDA5 is required for the control of MNV-1 infection. Knowledge of the host response to MNV-1 may provide keys for prevention and treatment of the human disease

Collaborative Development of Clinical Trials Education Programs for African-American Community-Based Organizations

This paper describes the use of a unique ”Learning and Feedback” approach to tailor cancer clinical trials education programs for Community Bridges, a peer training intervention designed for African American communities in North Carolina. Generic community education modules were demonstrated with key community leaders who were designated as trainers. Quantitative and qualitative assessments were provided on understanding of content, comfort with material and cultural relevance. The generic materials were adapted into three revised modules, all featuring key messages about cancer clinical trials, discussion regarding distrust of medical research, common misconceptions about trials, patient protections, and a call to action to prompt increased inquiry about locally available trials. The revised modules were then used as part of a train-the-trainer program with 12 African American community leaders. ENACCT’s use of the Learning and Feedback process is an innovative method for culturally adapting clinical trials education