Abstract
Early in the history of experimental poliomyelitis it was demonstrated that the serum of both monkeys and humans, convalescent from the disease, had the property of neutralizing the action of the virus when the 2 were mixed in vitro. As therapeutic value has been ascribed to such serums a number of attempts have been made to produce antiserum with similar properties in large, poliomyelitis-refractory animals. In most instances horses have been employed and the results, although sometimes successful, have been irregular and seem to depend upon individual differences in responsiveness of the animals. The immunization of sheep has met with success in some hands (Howitt 1 ) and failure or irregular results in others (Stewart and Haselbauer 2 ). The production of poliomyelitis antiserum in goats has also been reported.
In these various types of animals, virus inoculations have usually been continued over a long period of time, in some instances years, before potent neutralizing serums were demonstrated. A method of immunization in which the time as well as the number of injections could be decreased would be a distinct improvement.
We were subjecting a sheep to a series of virus injections for the purpose of producing an antiserum when it occurred to us that virus adsorbed to a colloidal carrier might prove to be a better immunizing agent than the crude virus. There is evidence that the antigenicity of substances may be enhanced by injecting them in combination with a colloid. Hektoen and Welker 3 have reported the continued maintenance of a high precipitin level in rabbits following one injection of protein adsorbed to alumina-gel. Since the virus of poliomyelitis has been adsorbed to this substance by Sabin 4 and others, we decided to investigate the suitability of such a combination as an immunizing agent in sheep.
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