Quantitative Study of the Neutralization of Western Equine Encephalomyelitis Virus by Its Antiserum and the Effect of Complement

Abstract

It has been found that the neutralizing capacity of a given antiserum to the virus of Western equine encephalomyelitis varies according to the conditions under which the neutralization is carried out. By intra-abdominal test a linear relationship was noted between antiserum concentration and virus neutralized when plotted on a log-log scale. By intracerebral test there was a similar relationship when fresh or frozen antiserum was tested. A reaction occurred in vitro between such sera and virus when incubated at 37 C. A different relationship was observed between virus and anti-serum which had fallen in neutralizing capacity as a result of standing at 4 C or of heating at 56 C one-half hour. Heating denatured the antiserum and induced a perceptible difference in the electrophoretic picture. The neutralizing capacity of sera kept at 4 C could be fully restored by addition of complement. Antibody in rabbit antiserum, fractionated by salting-out, was found only in the pseudo-globulin fraction; neutralization by this globulin could also be enhanced by complement. Antibody was found distributed throughout electrophoretically separated serum fractions, not only in the v globulin, but also in the β globulin and in the albumin.