Fluorescence Evaluation of Antigen–Antibody Reactivity on Surface of Proteinaceous Occlusion Body: Toward Application in Reusable Protein Chip

Abstract

A proteinaceous occlusion body, which is produced by insect viruses and consists of polyhedrin protein, has attracted much attention as a capsule for occluding an antigen protein. The occlusion body is called polyhedron. Its shape is cubic and its size is a few µm. Because several antigen proteins will be on the surface of polyhedra and several chemically active sites will be exposed, the polyhedra can be used as elements of protein chips to monitor antigen–antibody reactions. This idea is demonstrated by fixing a single polyhedron on a glass substrate and inducing an antigen–antibody reaction individually, and confirmed using relevant fluorescence microscopic images. Furthermore, a technique of cleaning the reacted surface is developed on the basis of the solubility of the polyhedrin matrix in an alkaline solution. The antigen–antibody complex on the surface can be removed by washing with the alkaline solution, and the antigen inside the polyhedron is exposed to the surface. On the basis of these results, the possibility of developing a “reusable protein chip” using the polyhedron is proposed.