Of the 12 animals inoculated intra- and subcutaneously with the neutralized mixtures containing the equivalent of 1.5 grams of poliomyelitis cord, 10 survived sufficiently long to permit of neutralization tests. The serums of only 2 of the 10 animals contained sufficient neutralizing substance to protect the test animals. Of the 8 surviving animals 3 withstood the same dose of virus administered intracerebrally and likewise resisted the 0.1 and 0.2 cc. doses. Two of the 3 animals resisted the 0.4 cc. dose and one resisted the 0.8 cc. or 16 times the minimal constant infective dose.

Each of the 11 additional animals received four 5 cc. doses of the neutralized mixtures at weekly intervals, each dose containing the equivalent of 0.5 gram of poliomyelitis cord (total of 2 grams). Seven of the 11 animals possessed sufficient neutralizing substance to neutralize the 0.05 cc. dose of virus. Nine of the 11 animals withstood 0.01, 0.025, and 0.05 cc. of the virus intracerebrally. Five of the 8 survivors (one animal having died of dysentery) survived 0.1 cc. of virus. Three resisted 0.2 cc. (2 of the 5 died of intercurrent infections), and 2 of the 3 resisted 0.4 or 8 minimal constant infective doses of virus.

The neutralized mixture proved non-infective both on subcutaneous and intracerebral inoculation.

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This work is supported by a grant from the Rockefeller Foundation, the Friedsam Foundation, and the President's Birthday Ball Commission for Infantile Paralysis Research.

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