Applications of plant viruses in bionanotechnology

Abstract

The capsids of most plant viruses are simple and robust structures consisting of multiple copies of one or a few types of protein subunit arranged with either icosahedral or helical symmetry. In many cases, capsids can be produced in large quantities either by the infection of plants or by the expression of the subunit(s) in a variety of heterologous systems. In view of their relative simplicity, stability and ease of production, plant virus particles or virus-like particles (VLPs) have attracted attention as potential reagents for applications in bionanotechnology. As a result, plant virus particles have been subjected to both genetic and chemical modification, have been used to encapsulate foreign material and have, themselves, been incorporated into supramolecular structures.

Fig. 1

Structure of a the Cowpea mosaic virus (CPMV) capsid and b the asymmetric unit. The capsid is comprised of the small(S) and large(L) subunit. (Steinmetz and Evans 2007)

Fig. 2

Transmission electron micrograph of unstained FePt-coated CPMV showing monodisperse mineralised particles

Fig. 3

Redox-active ferrocene-CPMV nanoparticles prepared with various linker lengths and coupling strategies. (Aljabali et al. 2010a)

Fig. 4

Cryoelectron microscopy of derivatised CPMV-Cys mutant. a Three-dimensional reconstruction of CPMV particles with 1.4 nm nanogold clusters. b Difference electron density map showing the nucleic acid (green) and the gold particles. c A pentameric section of the difference electron density map around the five-fold symmetry axis superimposed on the atomic model of CPMV showing that the gold is attached at the site of the Cys mutation. (Wang et al. , with permission, Copyright 2002 Wiley–VCH Verlag GmbH & Co. KGaA.)

Fig. 5

Schematic for the assembly of multifunctionalised Cowpea chlorotic mottle virus particles. (Gillitzer et al. , with permission, Copyright 2006 Wiley–VCH Verlag GmbH & Co. KGaA.)

Fig. 6

Chemical labelling of Potato virus X with fluorescent dyes and PEG chains using NHS ester-based chemistry or click reactions. (Steinmetz et al. , with permission, Copyright 2010 American Chemical Society)

Fig. 7

Schematic of the loading of an empty virus-like particle of CPMV and subsequent chemical decoration of the outer surface

Fig. 8

a Transmission electron micrograph of Tobacco mosaic virus showing two adjacent virion aggregates filled with nickel wires. Inset: a single virion filled with a 200 nm long wire. b TMV containing a 200 nm long cobalt wire (Knez et al. , with permission, Copyright 2003 American Chemical Society)

Fig. 9

Triple layer of CPMV particles on a gold surface. Fluorescence microscopy images (left) and diagrammatic representation of layer structures (right). The red and green flags show AlexaFluor dyes AF488 and AF568, respectively, and the black cross depicts streptavidin (Steinmetz et al. , with permission, Copyright 2006 American Chemical Society)

Fig. 10

Scanning electron micrographs showing the sequential build-up of polyelectrolytes and CPMV particles. a Precursor polyelectrolyte thin film. b Initial polyelectrolyte layer coated with a layer of CPMV particles. c Coating of polyelectrolyte-CPMV layer with further polyelectrolyte layers. d Subsequent addition of another layer of CPMV particles (Evans , Copyright 2007 with permission from Elsevier)