Tobacco mosaic virus facts for kids

Quick facts for kids Tobacco mosaic virus
Electron micrograph of TMV particles stained to enhance visibility at 160,000x magnification
Virus classification
Group:	Group IV ((+)ssRNA)
Genus:	Tobamovirus

The tobacco mosaic virus (TMV) was the first virus ever found. It was the first one scientists recognized as a virus.

TMV is a type of RNA virus that infects many plants. It especially affects tobacco plants and other plants in the Solanaceae family, like tomatoes and peppers. When a plant gets infected, its leaves often show a "mosaic"-like pattern. This means they have patches of light and dark green or yellow. People knew about a disease damaging tobacco crops since the late 1800s. But it wasn't until 1930 that they figured out a virus was causing it.

How Was TMV Discovered?

Scientists learned a lot about viruses by studying TMV. Here's how its discovery unfolded:

Early Clues in 1886

In 1886, a scientist named Adolf Mayer described the tobacco mosaic disease. He noticed it could spread from one plant to another. It seemed similar to how bacteria cause infections.

Filtering Experiments in 1892

Then, in 1892, Dmitri Ivanovsky found strong proof of something infectious that wasn't bacteria. He showed that sap from sick plants could still spread the disease. This happened even after he filtered the sap through very fine filters. These filters were small enough to block all known bacteria.

The Term "Virus" is Coined in 1898

In 1898, Martinus Beijerinck did Ivanovsky's filtering tests again. He also showed that the infectious agent could grow and multiply inside tobacco plant cells. Beijerinck was the one who first used the word "virus." He used it to describe this tiny, non-bacterial thing causing the tobacco mosaic disease.

Crystallizing a Virus in 1935

The tobacco mosaic virus was the first virus ever turned into crystals. Wendell Meredith Stanley did this in 1935. He also found that TMV could still cause disease even after being crystallized. This was a huge discovery! For his important work, Stanley won part of the Nobel Prize in Chemistry in 1946.

Seeing Viruses Up Close in 1939

The first pictures of TMV taken with an electron microscope were made in 1939. This allowed scientists to see the virus for the first time.

How Viruses Build Themselves in 1955

In 1955, Heinz Fraenkel-Conrat and Robley Williams made another big discovery. They showed that TMV's RNA (its genetic material) and its protein capsid (outer coat) could put themselves together. They formed working viruses all on their own! This showed how stable and well-designed the virus structure is.

Rosalind Franklin's Contributions

The famous crystallographer Rosalind Franklin also studied TMV. She worked on it for a short time at Berkeley. Later, she designed a model of TMV for the 1958 World's Fair in Brussels. In 1958, she thought the virus was hollow, not solid. She also guessed that TMV's RNA was single-stranded. Her ideas were later proven correct.

The study of tobacco mosaic disease and the discovery of viruses helped create the whole field of virology. This is the science of studying viruses.

Images for kids

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  Genome of tobacco mosaic virus

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  Tobacco mosaic virus symptoms on tobacco

See also

In Spanish: Virus del mosaico del tabaco para niños