A complement-fixation test, using an antigen prepared from infectious mouse brains, is described for yellow fever.
The test has been shown to be biologically specific. Nonspecific reactions, however, tend to occur with Wassermann-positive sera, but these can usually be avoided by inactivating the sera at 65°C.
Complement-fixing antibodies were demonstrable in the serum of humans and monkeys recovered from infection with yellow fever virus. Following vaccination with the 17D strain, complement-fixing antibodies were uniformly present in monkey serum, but were detectable in only a small proportion of human sera. The application of this latter fact in making yellow fever surveys is discussed.