mosaic virus

The Tobacco mosaic virus (TMV) is an RNA virus that infects plants, especially tobacco and other members of the family Solanaceae, showing characteristic patterns (mottling and discoloration) on the leaves (thus the name). It was the first virus to be discovered.

In 1883 Adolf Mayer first described the disease that could be transferred between plants, similar to bacterial infections. However, in 1889, Martinus Beijerinck showed that a filtered, bacteria-free culture medium still contained the infectious agent. The first concrete evidence for its existence was given by Dmitri Ivanowski in 1892. There are several types of mosaic viruses, including tobacco mosaic virus, bean mosaic virus, and cucumber mosaic virus. In 1935, Wendell Meredith Stanley crystallized the virus for electron microscopy and showed that it remains active even after crystallization. For his work, he was awarded 1/4 of the Nobel Prize in Chemistry in 1946. In 1955, Heinz Fraenkel-Conrat and Robley Williams showed that purified TMV RNA and its capsid (coat) protein assemble by themselves to functional viruses, indicating that this is the most stable structure (the one with the lowest free energy), and likely the natural assembly mechanism within the host cell.

The crystalographer Rosalind Franklin worked for Stanley for about a month at Berkeley, and later designed and built a model of TMV for the 1958 World's Fair at Brussels. In 1958, she speculated that the virus was hollow, not solid, and hypothesized that the RNA of TMV is single-stranded. The Tobacco mosaic virus (TMV) is an RNA virus that infects plants , especially tobacco and other members of the family Solanaceae , showing characteristic patterns (mottling and discoloration) on the. This conjecture was proven to be correct after her death.

Tobacco Mosaic virus has a rod-like appearance. Its capsid is made from 2134 molecules of coat protein (see image above) and one molecule of genomic RNA 6401 bases long. The coat protein self assembles into the rod like helical structure (16. 3 proteins per helix turn) (see Electron Micrograph below). What is mosaic virus?.