The research in my laboratory focuses on the mechanisms of virus fusion and virus assembly, using primarily the enveloped alphavirus, Semliki Forest virus (SFV), a highly developed system to study these processes at the molecular level. We are characterizing membrane fusion mediated by the virus spike protein, focussing on the structure and function of the spike protein during fusion, its interaction with the membrane, and the requirement for cholesterol in membrane fusion. Our studies of virus assembly and budding seek to identify the key viral and cellular factors required, using in particular a recently developed assay that specifically follows the final steps of virus exit. Results with these systems are important for the design of specific viral inhibitors, and for our understanding of the many membrane fusion reactions important in the function of viruses and cells.