The present invention provides plant virus vectors developed from the Foxtail mosaic virus (FoMV). The vectors include a nucleic acid sequence encoding an infectious Foxtail mosaic virus (FoMV) with a functional movement encoding sequence operably linked to one or more regulatory elements functional in a plant. The plant virus vectors may be used to infect monocot plants, such as maize and can be used for VIGS, gene editing, gene expression or other transgenic protocols.

There is described a process for production of metal-coated virus particles or metallic nanoparticles, said process comprising admixing virus particles with plant material with reducing power and a metal salt, wherein the process can be provided in planta or ex planta and the virus particles aid the production of the metal-coated virus particles or metallic nanoparticles.

The present invention provides an internal positive control for contaminating viruses. The invention provides the use of a second virus as an exogenous internal positive control in methods for verifying the reliability of an assay to detect a first virus, in methods of ensuring the absence of the first virus in a biological sample or pharmaceutical sample and in methods of manufacturing a vaccine free from a first virus.