Tobacco Mosaic Virus (TMV)

Tobacco Mosaic Virus (TMV) was the virus that founded the discipline of virology, being the first agent shown (by Ivanowsky, 1892) to be smaller than a bacterium, and the first virus ever crystallised (by Stanley, 1935). Infecting tobacco through vectors such as aphids and locusts, TMV produces a very recognisable 'mosaic' symptom: yellow-and-green mottled discolouration running along the leaf veins, together with downward curling and distortion of the young apical leaves, stunted growth and reduced yield. Structurally, TMV is a rigid, rod-shaped, helical virus about 280 x 150 (nm-scale) with a molecular weight of roughly 39 x 10^6 Daltons. Its protein coat (capsid) is built from about 2,130 identical protein subunits (capsomeres) arranged helically around a single central …