Immobilization of diverse foreign proteins in viral polyhedra and potential application for protein microarrays

Cypoviruses are insect viruses that produce a cytoplasmic crystalline particle called the polyhedron in which progeny virions are occluded. The virion structural protein, VP3, is implicated in the occlusion of viral particles into polyhedra. In this study, we determined the amino acid sequence of VP3 required for occlusion of viral particles into polyhedra and proposed that this sequence could be used as an immobilization signal to direct the stable incorporation of foreign proteins into polyhedra. A large-scale survey revealed that the immobilization signal could, in fact, direct the incorporation of a variety of human proteins into polyhedra. Immune reactivity and protein-protein interactions were detected on the surface of polyhedra containing immobilized foreign proteins, and these particles were shown to be highly stabilized against dehydration. We showed that these particles could be arrayed onto a glass slide by standard spotting and laser manipulation methods. Thus, this approach is well suited for protein expression, purification, and the development of protein microarrays.