Administration of an Attenuated Type I Poliomyelitis Virus to Human Subjects

Two human subjects who had no antibodies against Type I poliomyelitis virus were fed a mouse adapted Type I strain, and one human subject who had no antibodies against Types I and II was fed a mixture of mouse adapted Type I and Type II strains. None of the individuals showed clinical signs of illness as a result of ingestion of the virus. In the absence of viremia, all 3 excreted virus in the stools. Homologous neutralizing antibodies developed in the sera of each person. Virus passaged through the human intestinal tract maintained the very low pathogenicity for monkeys when injected intracerebrally.