A specific
complement fixation test can be obtained in various central nervous system
virus infections by using as
antigens emulsions of infected brain tissue, freezing and thawing the brain
emulsion, and then centrifuging it in an angle head centrifuge at 3500 R.P.M. for 1 hour. The method has proved reliable in the case of
rabies,
St. Louis encephalitis,
Japanese B encephalitis,
lymphocytic choriomeningitis,
Eastern equine encephalomyelitis,
Western equine encephalomyelitis,
louping ill, and spontaneous
encephalomyelitis of mice (Theiler's disease). The specificity of the reaction, regardless of the virus involved, requires different temperatures of inactivation of the sera according to animal species: 56 degrees C. for guinea pig, 60 degrees C. for mouse, and 65 degrees C. for rabbit and dog sera, all heated for 20 minutes. For human sera a temperature of inactivation of 60 degrees C. also for 20 minutes has been adopted; at this temperature the reaction is in general specific.
Complement-fixing
antibodies in high titre were found in the sera of rabbits, guinea pigs, mice, and dogs immunized with rabies virus.
Complement-fixing
antibodies were present in high titre in sera drawn from two persons 8 years after an attack of
louping ill, from five persons 2(1/2) years after an attack of
Eastern equine encephalomyelitis, and from two persons 2(1/2) years after
Western equine encephalomyelitis. In cases of
St. Louis encephalitis and
lymphocytic choriomeningitis,
complement-fixing
antibodies have been found shortly following
infection but not after long periods.