Russian microbiologist Dmitry Ivanovsky was the first to realize that bacteria were not the only infective agent. Ivanovsky published a paper on a virus infection of tobacco plants in 1892. However, lvanovsky probably did not grasp the full meaning of his discovery. Martinus W. Beijerinck, in 1898 became the first one to use the term ‘virus’ to indicate the microorganism causing tobacco mosaic disease.
A virus is an infectious particle that can multiply only inside a living cell. Since it is made of only a set of genes wrapped in protective covering, a virus takes over a plant or animal cell and forces it to replicate the invader. Both lvanovsky and Beijerinck discovered that viruses were smaller than bacteria and invisible under an ordinary microscope. These two scientists brought significant and complementary contributions to the discovery of viruses. The discovery of tobacco mosaic virus stands out as a milestone in the history of virology.
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