Complement Requirement of Neutralizing Antibodies Appearing after Primary and Booster Immuniza tions with Herpes Simplex Virus

Abstract

Ten rabbits were given a primary course of immunization by 4 weekly intravenous injections of herpes virus, and 1.5 years later 3 of them showing low titers of neutralizing antibody received 1 booster injection. The serological response in the primary immunization was characterized by an early development of complement-requiring neutralizing (CRN) antibody ahead of that of non-complement-requiring neutralizing (N) antibody, the CRN/N ratio being 8 to 128 within 3 weeks. In contrast, N antibody appeared much faster after the booster immunization, the CRN/N ratio approaching 4 within 1 week. The early type IgG, whose neutralizing activity was enhanced by complement (C') about 16-fold, was distinct from the late type IgG which could not be enhanced by C' more than 4-fold. The late type IgG appeared after 4 weeks and 3 days in the primary and booster immunizations, respectively. Serological examinations of human patients suggested the occurrence of the booster type response in the case of repeated infections among adults.