The Influence of Certain Serum Factors of the Neutralization of Western Equine Encephalomyelitis Virus

Abstract

A method is outlined for the separation of rabbit complement into two fractions lacking C′1 and C′2. These fractions are hemolytically inactive by themselves, but fully active when combined in single unit amounts. It is shown that C′3 and C′4 of rabbit complement are inactivated by the same means employed for the inactivation of these components in guinea pig and human complements. Hemolytic titrations are given for the four components of rabbit complement. These components have less hemolytic activity than the corresponding components of guinea pig and human complements, but are otherwise similar. The ability of fresh normal serum to enhance the virucidal capacity of heated immune serum is verified and the thermolabile nature of this property of fresh normal serum is confirmed. Blood complement is shown to be the agent in fresh rabbit serum responsible for increasing the neutralizing action of heated immune serum against the virus of Western equine encephalomyelitis. The second, third and fourth components are shown to be involved in the role of complement in virucidal tests. It is further demonstrated that either the first component is not necessary or, if required, that only a minute amount of this component is needed in this reaction involving complement.