The invention provides a cell-free system comprising not more than about 5% wheat germ extract for expressing proteins such as viral proteins and proteins required for viral capsid assembly, and proteins that assemble into multiprotein complexes in a manner analogous to viral capsids, are provided. Further provided are methods for expressing proteins such as viral proteins, proteins required for capsid assembly, and proteins that assemble into multiprotein complexes in a manner analogous to viral capsids using a cell-free system comprising not more than about 5% wheat germ extract. Further provided are methods to assay for compounds that modulate viral protein, viral capsid assembly, and assembly of proteins into multiprotein complexes whose disruption can ameliorate bacterial, parasitic, metabolic, oncologic, immunologic, or CNS disease in a cell-free system comprising not more than about 5% wheat germ extract.