Viruses were discovered by chance while Adolf Meyer was conducting research in 1883 on tobacco leaf mottles, and found smaller particles of bacteria to cause disease. In 1884, the French microbiologist Charles Chamberland invented a strainer (today known as a Chamberland strainer or Chamberland-Pasteur strainer) with pores smaller than bacteria. Thus, he can pass a solution containing the bacteria, filter it and completely remove them from it.
In 1892, the Russian scientist Dmitry Ivanovsky was able to filter the sap of infected tobacco leaves using special filters that did not allow bacteria to pass through. He was the first to call it virus (Latin for poison, which is simple and small particles), and his experiments showed that the leaves of the infected tobacco plant, after crushing them, were still infectious after filtration. Ivanovsky suggested that the infection might be caused by a toxin produced by bacteria, but he did not pursue this idea. At the time it was believed that all infectious agents could be kept on strainers and grown on nutrient media (this was part of the germ theory of disease). In 1898, the Dutch bacteriologist Martinus Beijerink repeated the experiments and became convinced that the solution obtained from the filter contained a new form of infectious agent. He noticed that this agent only infected the cells in the area of the patchwork, but his experiments did not show him that it was composed of particles so he named it Agent Bacterial fluid (contagium vivum fluidum) came back and was later used as a virus. Beijerink supported the theory that viruses are liquid in nature, a theory that was later discredited by Wendell Stanley, who proved the existence of particles. In the same year, scientists Frederick Loeffler and Paul Frosch discovered the first animal virus, the foot and mouth virus.
At the beginning of the 20th century, the English bacteriologist Frederic Toart discovered a group of viruses that infect bacteria, now called bacteriophages. The Canadian-French bacteriologist Felix Dhirell described them as viruses that, when added to bacteria on agar, produce areas of dead bacteria. He discovered that the highest dilutions of these viruses ( lowest concentration of virus) instead of killing all bacteria forms separate areas of dead organisms. Felix counted the number of these regions and multiplied it by the dilution factor, which allowed him to calculate the number of viruses in the original diluted solution. Phages were heralded as a possible treatment for diseases such as typhoid and cholera, but this promise was forgotten with the development of penicillin. The study of phages gives signals about switching genes on and off and is considered a useful mechanism for introducing foreign genes into bacteria.
By the end of the 19th century, viruses were defined in terms of their infectiousness, their filtering ability, and their need for a living host. Viruses have only grown in plants and animals. In 1906, Ross Granville Harrison invented a method for culturing tissue in lymph and in 1913 E. Steinhardt and colleagues used this method to grow vaccinia virus in sections of guinea pig corneal tissue. In 1928 H.M. B. Maitland and M. s. Maitland developed vaccinia virus in a suspension of minced chicken kidneys. Their method was not widely adopted until the 1950s when poliovirus (the virus that causes polio) was grown on a large scale for vaccine production.
In 1931 another breakthrough came when the American pathologist Ernest William Goodpasteur grew influenza and several other viruses in fertilized chicken eggs. In 1949, John Enders, Thomas Weller, and Frederick Robbins grew poliovirus in human embryonic cells, making it the first virus grown without the use of solid tissues of animals or eggs. This work enabled Jonas Salk to present an effective polio vaccine.
The first images of viruses were obtained after the invention of the electron microscope in 1931 by German engineers Ernst Ruska and Max Knoll. In 1935, the American virologist and biochemist Wendell Stanley studied the tobacco mosaic virus and found that it consisted mostly of protein. Shortly thereafter, this virus was separated into two parts (protein and RNA). Tobacco mosaic virus was the first virus to be crystallized so that its structure could be elucidated in detail. The first X-ray diffraction images of crystallized virus were obtained by Bernal and Fankischen in 1941. On the basis of her images, Rosalind Franklin discovered the complete DNA structure of the virus in 1955. In the same year Heinz Frankl-Conradt and Robley Cook-Williams reported that pure tobacco mosaic virus RNA and its protein coat By themselves, they can combine to form functioning viruses, suggesting that this simple mechanism may have been the means by which viruses are created within host cells.
The second half of the twentieth century was the golden age of virus discovery, as 2000 species were found, which are the most recognized viruses of animals, plants and bacteria during these years. In 1957, the equine arterial virus was discovered, the cause of viral diarrhea in cows (peptic fever). Hepatitis B virus was discovered by Baruch Blumberg in 1963, and the first retrovirus was described by Howard Temin in 1965.
The key retroviral enzyme (reverse transcriptase) that is used to translate its RNA into DNA was first described in the 1970s independently by Howard Temin and David Baltimore. In 1983 Luc Montagnier’s team of the Pasteur Institute in France isolated for the first time the retrovirus now known as HIV.
Scientists Walter Reed and James Carroll discovered the first human virus, the yellow fever virus.
Viruses are considered one of the most important dilemmas facing biological classification, as they do not represent living organisms, so they are often described as infectious particles, but in return they show some characteristics of life such as the ability to multiply and multiply with the help of host cells that
