Experimental Immunization in Poliomyelitis

[摘要] Infection results from subcutaneous injection of attenuated virus in about 25 per cent of animals. About 25 per cent of animals vaccinated with attenuated virus resisted subsequent intracerebral inoculation.Infection results from subcutaneous injection of active virus in about 25 per cent of animals. Thus, it appears that virus subjected to “attenuation” (phenolization; glycerolization or drying) possesses little, if any, less infectivity than active virus when injected subcutaneously.A large number of intracutaneous injections of active virus does not produce infection.Intracutaneous injection of active virus repeated for a considerable time protects monkeys from intracerebral inoculation or prolongs the incubation period.Of twelve monkeys receiving repeated intracutaneous injections of active virus, only one developed paralysis. Of the surviving animals, two resisted three intracerebral inoculations, two intracerebral inoculations, and two resisted one intracerebral inoculation but succumbed to a second inoculation, one of these with a prolonged incubation period, and three animals resisted a single intracerebral inoculation, but were not retested. One animal did not resist intracerebral inoculation but the incubation period was prolonged. Four of the resistant animals also received from one to five subcutaneous inoculations of active virus from which no symptoms resulted.Blood serum of monkeys vaccinated by the intracutaneous method neutralizes the virus of poliomyelitis in vitro.Blood sera from eight of the vaccinated animals neutralized virus in vitro 21 times, while in two other instances the virus was partially neutralized as evidenced by prolongation of the incubation period. Blood sera which only partially neutralized had on previous occasions completely neutralized the virus, in one case four times. The blood serum of one animal which did not resist intracerebral inoculation completely neutralized virus.In respect to the epidemiology of poliomyelitis, these observations lend support to the idea that immunity may be accomplished without active symptoms, and that the neutralization of virus by serum of “normal” individuals is an indication of acquired immunity to the virus and is not a property of normal serum.

[学科分类] 生物科学（综合）