The course and outcome of experimental yellow fever in Macacus rhesus when specific immune serum was injected into the animals at various intervals after the administration of the virus, has been studied by Davis (1).
Penna (2) has described the changes which he observed in a viscerotropic (the Asibi) strain of yellow fever virus as a result of serial passage through the central nervous tissues of rhesus monkeys that were protected against serious visceral damage by the inoculation of specific immune serum. After about forty such passages the virus was so modified as to be primarily neurotropic.
In the study here reported observations were made upon the course and outcome of yellow fever encephalitis in M. rhesus that received immune serum via the cisterna magna—after the removal of some cerebrospinal fluid—at various intervals before the intracerebral inoculation of the modified Asibi virus with which Penna was working.
The studies and observations on which this paper is based were conducted with the support and under the auspices of the International Health Division of the Rockefeller Foundation.