Mechanical stress determines the shape of viruses

Geometrical and mechanical models of virus assembly. The mechanical stress during assembly determines globally the final shape of a virus: compact (e.g. virus SV40) or elongated (virus HIV-1). Biological viruses are mainly made by the self-assembly of a genome and some proteins that are forming a closed shell. The role of this proteic shell called a capsid is to protect the genome. The main viral shape found in nature are twofold: either they are very regular and compact, adopting a geometry of icosahedra, or they are irregular and elongated, like the conical capsid of HIV-1, the pathogen responsible for AIDS. What is the property at the single protein level that determines the global shape of a virus? In order to answer this question, a team from the ENS de Lyon's Physics lab was able to model the elastic energy associated to the self-assembly process.