Electron tomography reveals polyhedrin binding and existence of both empty and full cytoplasmic polyhedrosis virus particles inside infectious polyhedra

ABSTRACT

Previous studies have described the structure of purified cytoplasmic polyhedrosis virus (CPV) and that of polyhedrin protein. However, how polyhedrin molecules embed CPV particles inside infectious polyhedra is not known. Using electron tomography, we show that CPV particles are occluded within the polyhedrin crystalline lattice with a random spatial distribution and interact with the polyhedrin protein through the A-spike rather than through the previously thought B-spike. Furthermore, both full (with RNA) and empty (no RNA) capsids were found inside polyhedra, suggesting a spontaneous RNA encapsidating process for CPV assembly in vivo.