Transmission Electron Micrograph of particles of Tobacco Mosaic Virus (TMV). Inside the rod, protein molecules are wound helically down the full length of the virus, housing and protecting the nucleic acid of RNA. The effect of TMV infection varies from death of the host plant to severe lesions on the leaf surface. Plant viruses like TMV are transmitted by insects, pests and nematode worms. Magnification: x120,000.