Virus structure determination using electron microscopy has become a useful research tool aimed at understanding viral assembly and infectivity. Our long term goal is to broaden the group of people able to determine virus structures by providing an integrated software suite for three-dimensional virus structure determination using electron microscopy. The software suite will allow easy, efficient, and routine determination of icosahedral virus structures from electron micrographs. Novel aspects of this software will include a comprehensive suite of tools for icosahedral structure determination, incorporation of an expert system to guide users through the reconstruction procedure, and data analysis tools to ensure that structures are determined accurately. In addition, the software will provide a consistent easy to use graphical user interface to all reconstruction tools including data analysis, data management, and data logging. The result of this phase one SBIR will be a design specification for an integrated software package allowing easy, efficient, and routine determination of virus structures by both virologists and structural biologists. Furthermore, one aspect of the reconstruction procedure will be targeted for development as a prototype to demonstrate project feasibility. The complete software product will be implemented and tested in a phase two SBIR. PROPOSED COMMERCIAL APPLICATIONS: The availability of a comprehensive virus structure determination software package will have commercial implications to virologists, microbiologists, and other biologists interested in performing such structural studies but who are not trained in the intricacies of icosahedral virus structure determination. In addition, this software package will be of interest to structural biologists and electron microscopists as it will provide all of the software necessary for structural studies in one comprehensive extendable package.