General: what is a virus?
A virus is a sub-microscopic infectious agent that is unable to reproduce outside a living host cell. Viruses infect all forms of life. The first known virus, tobacco mosaic virus (a plant virus), was discovered by Martinus Beijerinck in 1899. Currently, the ICTV lists 6000 viruses, in nearly 2000 species. However, Genbank identifies more than 3000 additional species, as yet unaccounted for.
On Wednesday 21 January 2009