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Discovery of the

Discovery of the virus A sick child with smallpox. Viral diseases such as rabies, yellow fever and smallpox have affected humans for many centuries. Hieroglyphics that describe known polio in medicine of ancient Egypt, although at the time was not yet known the cause of the disease. In the tenth century, Al-Razi wrote the Treaty on smallpox and measles, which provides the first clear description of these diseases. The contagious nature of infectious diseases (viral and bacterial) is described by Avicenna in the decade of 1020, in his Canon of Medicine.It describes the tuberculosis and sexually transmitted diseases and their spread through physical contact, water and soil. argues that bodily secretions are contaminated by “foreign bodies” that produce infection and introduces the practice quarantine as a means to limit the spread of communicable diseases. When the Black Death (or plague) arrives at Al-Andalus in the fourteenth century, Ibn Khatima discovers that infectious diseases are caused by microorganisms that are introduced in the human body. services range from executive recruitment to corporate governance and CEO recruitment executive recruitment professionals, many of whom joined our firm from senior positions in the industry sectors they now serve, conduct more than 10,000 senior-level searches for clients worldwide each year. Another fourteenth-century Andalusian physician, Ibn al-Khatib (1313-1374), wrote the treatise on the plague, which asserts that infectious diseases can be transmitted through bodily contact and “through garments, vessels and pending. ” The etiological causes of tuberculosis, bubonic plague and some sexually transmitted infections later identified as bacteria. The first vaccines to prevent viral diseases are discovered in the eighteenth century.In 1717, Mary Montagu, the wife of a British ambassador to the Ottoman Empire, notes that local women are used to inoculate their children with fluid taken from mild cases of smallpox. In the late eighteenth century, Edward Jenner observed and studied Miss Sarah Nelmes, a milkmaid who had suffered the “cow pox” and that because he was immune to smallpox, a related virus that affects people. Jenner developed the smallpox vaccine on the basis of these findings. After prolonged immunization, the World Health Organization (WHO) certified the eradication of smallpox in 1979. Snuff mosaic virus (each of the “straw”). The first reference to the existence of viruses is due to the Russian botanist Dimitri Ivanovski in 1892.Earlier, Charles Chamberland developed a porcelain filter with pores small enough to retain bacteria and separate them from their culture medium. Dimitri Ivanovski used this filter to identify the agent causing the disease known as mosaic and snuff concludes that there must be a toxin or a body smaller than bacteria, it passes through filters that hold them. Passing leaf extracts of plants infected snuff through the filter and then use the filtered extract to infect other plants shows that the infectious agent is a bacterium. Similar experiments are carried out by several other researchers, with similar results and show that viruses are several orders of magnitude smaller than bacteria. The term virus was coined by the Dutchman microbiologist Martinus Beijerinck who, using methods based on the work of Ivanovski, in 1897, dismisses the idea of toxins.Verify that the agent causing the mosaic disease is able to reproduce snuff because it retains its power diluted infectious without moving from plant to plant, and coined the Latin phrase “contagium vivum fluidum” (meaning “seed soluble Life “), the first approach to the virus. Shortly thereafter, the German microbiologist Frederick Loeffler and Paul Frosch discovered foot and mouth disease of livestock is also produced by a filterable virus that acts as an infectious agent. The first human virus identified was the yellow fever virus. S-PM2 phage of Synechococcus, a bacteriophage. In the early twentieth century, Frederick Twort discovered that bacteria can also be infected by viruses. Felix d’Herelle, working independently, showed that viral preparation causes dead areas in cell cultures made on agar. Counting the dead areas, able to estimate the original number of viruses in the suspension.In the early 30s, using filters with pore size less with cell culture techniques that allow in vitro to obtain large amounts of these agents, ultracentrifugation, and finally with the electron microscope and diffraction X-rays is achieved finally visualize the virus. In 1935, Wendell Stanley crystallizes the mosaic virus and discovers that snuff is composed mostly of proteins. Shortly thereafter, the virus was separated into proteins and nucleic acids. 1939, Max Delbr ck and the Ellis showed that in contrast with cellular organisms, bacteriophages are reproduced in a “step” instead of exponentially. A major problem for early virologists was the inability to grow viruses in media sterile culture, such as with cellular organisms.

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