Russian botanist Dmitri Ivanovsky demonstrated in 1892 that the agent causing tobacco mosaic disease remained infectious even after being passed through a Chamberland filter fine enough to remove all known bacteria, showing that an infectious agent smaller than any known microbe existed, though Ivanovsky did not fully grasp the implications of his own finding. Dutch microbiologist Martinus Beijerinck independently repeated and extended the experiment in 1898, showing that the filterable agent could reproduce only inside living host cells, and coined the term virus, from the Latin word for poison, to describe this new category of infectious agent. The organism they had studied, tobacco mosaic virus, became the first virus ever identified and, when American biochemist Wendell Stanley crystallized it in 1935, the first virus ever crystallized, a landmark that helped establish the modern field of virology and, through later structural studies of the virus, contributed to the broader understanding of how molecules such as DNA could form ordered helical structures.
Facts
Discovery Year Classification
Type/Classification Connections
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Beijerinck described a contagious living fluid in 1898; Dmitri Ivanovsky reported the filterable agent earlier
Sources
1. Beijerinck Discovers Viruses (EBSCO Research Starters, History)
History section, contagium vivum fluidum
In 1898, the Dutch microbiologist Martinus Beijerinck (1851-1931), a microbiology teacher at the Agricultural School in Wageningen repeated experiments by Adolf Mayer and became convinced that filtrate contained a new form of infectious agent.
entity description, Discovery of Viruses
Russian botanist Dmitri Ivanovsky demonstrated in 1892 that the agent causing tobacco mosaic disease remained infectious even after being passed through a Chamberland filter fine enough to remove all known bacteria, showing that an infectious agent smaller than any known microbe existed, though Ivanovsky did not fully grasp the implications of his own finding.
View the SourceFrequently Asked Questions
Why is Martinus Beijerinck credited with discovering viruses rather than Dmitri Ivanovsky, who observed the same filterable agent six years earlier?
Ivanovsky found the filterable agent in 1892 but thought it was an uncultivable bacterium; Beijerinck showed in 1898 that it reproduced only in living tissue, earning him credit for the discovery.
Dmitri Ivanovsky showed in 1892 that the agent causing tobacco mosaic disease could pass through a filter fine enough to remove all known bacteria, but he concluded the agent was probably a bacterium that simply could not be cultured, a view he still held as late as 1903. When Martinus Beijerinck repeated the experiment in 1898, he found the agent would not grow on any culture medium and, unlike a toxin, did not lose potency when passed from plant to plant, showing it could only reproduce inside living tissue. Because Beijerinck correctly identified this living, reproducing nature of the agent where Ivanovsky had not, sources on the discovery credit Beijerinck with priority for identifying viruses.
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