PREPARATION OF YELLOW FEVER VACCINE AT THE INSTITUT PASTEUR, DAKAR

One of the first strains of yellow fever virus, whose experimental trans-mission to a receptive animal opened the way to the important advances made in the study of the disease, was isolated at the Institut Pasteur at Dakar by Mathis, Sellards & Laigret ^ during the yellow fever epidemic which broke out in Senegal in 1927. This virus had been transmitted to Macacus rhesus monkeys by the bites of Aëdes aegypli fed 24 and 31 days earlier on a patient suffering from yellow fever. Early in 1928 the virulent organs from one of the monkeys infected in this way were transported in a frozen state to Europe and America, where they were placed at the disposal of various laboratories under the name of " French strain ". Theiler,9 studying the properties of this strain, showed in 1930 that the white mouse was susceptible to intracerebral inoculation, which induced a yellow fever encephalitis capable of being transmitted in series. After a certain number of passages in this animal, the properties of the yellow fever virus became modified so that when inoculated subcutaneously it n