Photosounder virus1/13/2024 Scientists were soon able to detect the number of bacterial viruses in a culture vessel by measuring their ability to break apart (lyse) adjoining bacteria in an area of bacteria (lawn) overlaid with an inert gelatinous substance called agar-viral action that resulted in a clearing, or “ plaque.” The American scientist Renato Dulbecco in 1952 applied this technique to measuring the number of animal viruses that could produce plaques in layers of adjoining animal cells overlaid with agar. Cell culture then led to the development and production of vaccines (preparations used to elicit immunity against a disease) such as the poliovirus vaccine. (Until this time, the poliovirus could be grown only in the brains of chimpanzees or the spinal cords of monkeys.) Culturing cells on glass surfaces opened the way for diseases caused by viruses to be identified by their effects on cells ( cytopathogenic effect) and by the presence of antibodies to them in the blood. Hirst found that influenza virus grown in tissues of the chicken embryo could be detected by its capacity to agglutinate (draw together) red blood cells.Ī significant advance was made by the American scientists John Enders, Thomas Weller, and Frederick Robbins, who in 1949 developed the technique of culturing cells on glass surfaces cells could then be infected with the viruses that cause polio ( poliovirus) and other diseases. Laidlaw were able to transmit influenza to ferrets, and the influenza virus was subsequently adapted to mice. In 1933 the British investigators Wilson Smith, Christopher H. The study of viruses confined exclusively or largely to humans, however, posed the formidable problem of finding a susceptible animal host. The unique nature of these agents meant that new methods and alternative models had to be developed to study and classify them. d’Hérelle, lesions in cultures of bacteria were discovered and attributed to an agent called bacteriophage (“eater of bacteria”), now known to be viruses that specifically infect bacteria. Twort and in 1917 by the French Canadian scientist Félix H. In independent studies in 1915 by the British investigator Frederick W. This virus and those subsequently isolated would not grow on an artificial medium and were not visible under the light microscope. Both of these investigators found that a disease of tobacco plants could be transmitted by an agent, later called tobacco mosaic virus, passing through a minute filter that would not allow the passage of bacteria. Beijerinck first surmised that the virus under study was a new kind of infectious agent, which he designated contagium vivum fluidum, meaning that it was a live, reproducing organism that differed from other organisms. Ivanovsky and in 1898 by the Dutch scientist Martinus W. The earliest indications of the biological nature of viruses came from studies in 1892 by the Russian scientist Dmitry I. The name is from a Latin word meaning “slimy liquid” or “poison.” Virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! ![]() ![]() Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.
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