The detailed mechanism of assembly of Tobacco Mosaic Virus and other viruses will be investigated by physical-chemical techniques. Specifically, the elementary step kinetics of the assembly of Tobacco Mosaic Virus will be studied using stopped-flow and temperature-jump relaxation kinetics and other physical methods. The assembly mechanisms of icosahedral and tubular viruses will be analyzed with the following question in mind: Are there general kinetic principles governing the assembly of these two structural classes of viruses? Specifically, the role of metastable protein aggregates in virus assembly will be studied; the chemical and structural basis for recognition of the TMV-RNA by the coat protein at the assembly nucleation site will be determined; the conformation switching in the 20S protein aggregate that occurs during assembly will be studied by time-resolved x-ray diffraction. These physical-chemical solution studies will be interpreted in terms of the atomic resolution structure of the virus that is beng determined elsewhere.