Fate of Poliomyelitis Virus in the Brain After Intracerebral Inoculation of Normal and Convalescent Monkeys. ∗

Abstract

The fate of poliomyelitis virus in the brain after intracerebral inoculation of normal monkeys has recently been studied very carefully by Fairbrother and Hurst. 1 These authors find the virus regularly present at the site of inoculation until the fifth day after infection, when the infectious agent suddenly disappears from the portal of entry on its way to further invasion of the more distant parts of the central nervous system. This critical point in the development of the disease, suggesting the operation of some auto-sterilizing mechanism in the infected brain tissue, apparently coincides with the first febrile response. The work of the above mentioned authors suggested a comparison of the survival of the virus after intracerebral inoculation in the normal monkey brain with the rate of disappearance from the site of inoculation in convalescent monkeys, immune through spontaneous recovery from the disease.

Six normal monkeys were inoculated intracerebrally with 1 cc. of a 10% virus cord emulsion, the potency of which was proved by simultaneous infection of several controls. By using a very

short needle and exercising special care so as to avoid deposition of the infectious material in the ventricle, the inoculated area could, in every instance, be accurately determined from the depth of the needle prick. At intervals varying from 12 to 96 hours the 6 monkeys were sacrificed and the sites of inoculation in each instance were transferred to a new passage animal by cerebral inoculation of the respective cortical area, emulsified into a 10% suspension. Another series of 10 convalescent monkeys was similarly infected together with an adequate number of controls, and, at the stated intervals, the respective sites of inoculation were likewise transferred to new monkeys.