Before revision:  Our minimal model of virus assembly shows that structures of small shells are basically determined by the spontaneous curvature almost independently of the mechanical properties of the protein subunits .
After revision:  Our minimal model of virus assembly shows that structures of small shells are basically determined by the spontaneous curvature almost independently of the mechanical properties of the subunit determines the symmetry of the assembled structure. Understanding the minimum requirements for the formation of closed nano-shells is a necessary step towards engineering of nano-containers, which will have far reaching impact in both material science and medicine .