LOCAL RULE-BASED THEORY OF VIRUS SHELL ASSEMBLY

A local rule-based theory is developed which shows that the self-assem bly of icosahedral virus shells may depend on only the lower-level int eractions of a protein subunit with its neighbors-i.e., on local rules rather than on larger structural building blocks. The local rule theo ry provides a framework for understanding the assembly of icosahedral viruses, These include both viruses that fall in the quasi-equivalence theory of Caspar and Klug and the polyoma virus structure, which viol ates quasi-equivalence and has puzzled researchers since it was first observed. Local rules are essentially templates for energetically favo rable arrangements. The tolerance margins for these rules are investig ated through computer simulations. When these tolerance margins are ex ceeded in a particular way, the result is a ''spiraling'' malformation that has been observed in nature.