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Chapter 2 : Of Mice and Men: Animal Models of Viral Infection
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In viral diseases of plants, such as tobacco mosaic disease, the natural host was readily available and appropriate. For human diseases, such as rabies and polio, nonhuman hosts were necessary to isolate and characterize the etiological agent. In the case of rabies, a zoonosis that spreads from animals to humans with catastrophic results, the development of animal models might be expected to be productive. In contrast, polio and human influenza were not known to have animal hosts, nor was an animal host known for yellow fever. Yet, isolation and study of the agents for each of these diseases were achieved in experimental hosts. This chapter discusses the transmission of rabies to dogs and rabbits and polio in monkeys, which served as animal models for study. Isolation in monkeys, and particularly in mice, was exceptionally productive for filterable viruses that caused epidemics of encephalitis. These viruses were transmitted by mosquitoes and came to be called arthropod-borne, later shortened to arbovirus. Rabies is horrific in all aspects: in the savage bites by crazed wolves or dogs to implant infection, in the anxiety and fear in anticipation of whether the disease will develop, in the torturing expression of the acute disease, and in the knowledge that once expressed, rabies is an essentially fatal disease. Studies on biological systems showed that the embryonated egg of chickens was remarkably productive for the understanding of human influenza infection.
Mad Dog. The fear of rabid dogs has been portrayed throughout history. This caricature by T. L. Busby was published in London in 1826. (Courtesy Yale University, Harvey Cushing/John Whitney Medical Library.) doi:10.1128/9781555818586.ch2.f1
Louis Pasteur. Pasteur was one of the principal founders of germ theory. He disproved the theory of spontaneous generation; linked agricultural, animal, and human diseases to specific infections; and developed vaccinations, including that to prevent rabies. (Courtesy of the National Library of Medicine.) doi:10.1128/9781555818586.ch2.f2
Rabies prevention. The recognition that the Pasteurian treatment could prevent rabies after the bite of a rabid animal resulted in dramatic public acceptance. In this print from 1885, Pasteur is depicted observing the inoculation of a boy to prevent hydrophobia (rabies in humans). (Courtesy of the National Library of Medicine.) doi:10.1128/9781555818586.ch2.f3
Karl Landsteiner. Landsteiner was awarded the Nobel Prize in 1930 for the discovery of human blood groups. Another significant contribution was the demonstration that polio could be transmitted to monkeys by using spinal cord tissue from children who had died from the illness. (Courtesy of the Albert and Mary Lasker Foundation.) doi:10.1128/9781555818586.ch2.f4
“Coughs and Sneezes Spread Diseases,” a slogan and poster campaign that was designed to cut down on the spread of respiratory diseases in the United Kingdom in World War II. Disease was portrayed as hampering the war effort at home. No doubt lurking in the minds of the Ministry of Health officials were the devastating effects of the 1919 influenza pandemic. (Courtesy of Yale University, Harvey Cushing/John Whitney Medical Library.) doi:10.1128/9781555818586.ch2.f5
L’influenza à Paris. This cover is from a Parisian weekly in 1890 during the influenza pandemic of 1889–1890. Originating in Russia and spreading westward, influenza became known as “Russian flu.” The cover depicts four scenes relating to the epidemic in Paris (clockwise from top left): a tent set up in a hospital courtyard, the interior of tent ward for the sick, the distribution of clothes to families of victims, and two men singing a new song, “L’influenza, tout l’monde l’a!” (“Influenza, Everyone Has It!”). (Courtesy of the National Library of Medicine.) doi:10.1128/9781555818586.ch2.f6