Download Sonja Opper BIO 212 A Take Home Assignment #1 9/13/13 Dimitri

Sonja Opper
BIO 212 A
Take Home Assignment #1
9/13/13
Dimitri Iosifovich Ivanovski is regarded as the father of Virology. Ivanovski’s main areas
of research were in alcohol fermentation, soil microbiology and tobacco mosaic disease
(Lechevalier, 1972). Tobacco mosaic virus caused a yellow discoloration of the tobacco leaves in
a mosaic pattern. The leaves of the plant affected by the disease would eventually die off as the
virus spread to the rest of the plant. This disease caused many tobacco plants in Europe to perish,
cutting into profits and supply of tobacco. Ivanovski’s research was built on the findings of
Adolf Mayer, a German chemist who was the first to name the tobacco mosaic disease. Mayer
discovered the infectious qualities that were maintained when the leaves of the plant were ground
and spread at the roots of another plant (Lustig et al, 1992). Although he is credited with the
discovery of the infectious quality of the leaves, Mayer concluded that the disease was caused by
a bacterium which could not be easily isolated at that time (Lustig et al, 1992). Assisted by
Mayer’s findings, Ivanovski inadvertently discovered a virus around 1892 while studying the
transmittance of the tobacco mosaic disease from one plant to another. Ivanovski was able to
transmit the mosaic disease by crushing infected leaves from one plant and placing them around
the roots of a healthy plant, just as Mayer had. He found that after the passage through a
Chamberland filter, the filtrate was still capable of infecting a healthy plant (Lechevalier, 1972).
The Chamberland filter was a ceramic filter capable of sterilizing the sample and removing
bacteria from a solution. These findings suggested that the agent responsible for causing the
mosaic disease was smaller than a bacteria. Ivanovski came to the conclusion that the disease
must have been caused by a very small bacteria or a soluble toxin which was capable of inducing
the disease. The second hypothesis was particularly popular due to the recent discovery of the
bacterial toxin that was responsible for diphtheria (Lechevalier, 1972). After a series of
experiments Ivanovski came to the conclusion that the causative agent of the disease was a
particle. In 1903 Ivanovski published a paper that described “abnormal intracellular inclusion
bodies in the host cells of virus-diseased plants” (Lechevalier, 1972). In the paper Ivanovski
recognized that the crystals within the cells could be the cause of the disease.
Unaware of Ivanovski’s findings, Martinus Beijerinck, a Dutch microbiologist, also
discovered the filterable particle which caused the tobacco mosaic disease. He concluded that the
infection was not caused by microbes but by a “living liquid virus” or “contagium vivum
fluidum” (Lustig et al, 1992). He also concluded that the virus only multiplied in growing plants
and that the virus was inactivated by boiling but could be dried and still infect a healthy plant.
Beijerinck’s findings began a 25 year debate over viruses, liquids and particulates. With the
findings of d’Herelle in his plaque assay in 1917 and the first electron micrograph in 1939, the
debate was put to rest (Lustig et al, 1992). Shortly following the discovery of the causative agent
of tobacco mosaic virus, Loeffler and Frosch in 1898 described and isolated the first “filterable
particle” from animals. In 1901, Walter Reed and his team discovered the first human virus,
yellow fever virus (Lustig et al, 1992).
By the twentieth century the concept of viruses was widely accepted. In 1929, Vinson
and Petre added selected salts to the infectious filtrates, treating them as a chemical entity (Lustig
et al, 1992). In 1935, Wendell Stanley demonstrated the protein and RNA components of
tobacco mosaic virus. This finding was followed by the first X-ray crystallography of completed
by Bawden and Pirie in 1936 (Lustig et al, 1992). The genome of tobacco mosaic virus (TMV)
was sequenced and used to prove that infectious genetic material could be stored in RNA
molecules. Also the concept of self-assembly with RNA and a protein coat was explored using
the TMV genome (Lustig et al, 1992).
The findings of Adolf Mayer, Dimitri Ivanovski and Martinus Beijerinck laid the
foundation for the discovery and exploration of viruses. The concept of the “filterable particle”
sparked the discovery of how viruses work, what they are, their mechanisms of infection, and
have lead virologists and microbiologists to many other discoveries. Who knew the question “Do
you want a smoke?” could have such an impact.
Works Cited
Lechevalier, H. "Dmitri Iosifovich Ivanovski (1864-1920)." Bacteriology Reviews 36.2 (1972):
135-45. NCBI. US National Library of Medicine. Web. 11 Sept. 2013.
<www.ncbi.nlm.nih.gov/pmc/articles/PMC408320/?page=7>.
Lustig, A., and A. J. Levine. "One Hundred Years of Virology." Journal of Virology 66.8 (1992):
4629-631. NCBI. US National Library of Medicine. Web. 11 Sept. 2013.
<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC241285/?page=3>.