By means of a series of subcutaneous injections of an organism cultivated from Berkefeld N filtrates of poliomyelitis virus, Macacus rhesus monkeys were apparently immunized against the virus of the disease.

The protection conferred upon the test animals was measured by the neutralizing power of their serums for poliomyelitis virus. In two instances the resistance of monkeys toward intracerebral inoculation of the virus was also tested.

The serums of animals treated with the cultures neutralized completely or in part the poliomyelitis virus in vitro. The outcome of an intracerebral inoculation test in two other instances showed that the monkeys had become resistant to infection by this route.

During the course of immunization with the living cultures 1 animal developed typical poliomyelitis. In an earlier series of experiments 3 monkeys also showed symptoms and signs of typical abortive infection.

The cultures used in the experiments were in the twenty-fourth subplant and represented a dilution of the original virus material that had been cultivated of approximately 2 × 10−38.

The results have been discussed with reference to possible survival of any hypothetical adsorbed virus and with reference to the viability of virus as compared with the cultures at incubator temperature.

The experiments, it is believed, confirmed further the previously reported observations on the possible relationship of this organism to the poliomyelitis virus.


Work done under a grant for poliomyelitis research supported by anonymous donors.

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