Day-by-day response of vaccinated chimpanzees to poliomyelitic infection.

Abstract

or more 1 ml doses of commercial trivalent formol inactivated poliomyelitis vaccine supplied through the courtesy of the National Foundation for Infantile Paralysis. The experiments were begun in 1954 with the low potency preparations then available, but subsequently the animals received a booster dose on February 22, 1955, of a somewhat better preparation kindly supplied by Eli Lilly and Company. Since this time much better vaccines have become available, but these were the best obtainable at the time. On March 21, 1955, the chimpanzees received an oral challenge of Brunhilde cord virus (ca 25,000 PD50). Throat swabs and sera were collected daily for the first 10 days following exposure and somewhat less frequently for the following two weeks. Two swabs were obtained and stored individually from the tonsillar areas of each animal, while stools of approximately alternate days were pooled as weekly specimens (collections on Monday, Wednesday, and Friday). All the materials for virus assay were suspended in a menstruum composed essentially of balanced salt solution, to which had been added 0.5 per cent lactalbumen hydrolysate and 0.12 per cent crystalline bovalbumen.1 In some cases 2 per cent calf serum was also included. Stools were diluted at 1:3 before clarification in the Spinco centrifuge at 34,000 x gravity for one hour; swabs were placed in 2 ml of balanced salt solution at collection to be eluted later and similarly clarified without further treatment. All specimens were tumbled overnight at 40 C with 20 per cent anaesthetic ether. After settling, the top