Serovaccination by human immune globulin and HDCS-vaccine against rabies

A serological study was performed in 16 volunteer subjects and 3 patients to determine the active antibody response after vaccination with HDCS vaccine alone and in conjunction with rabies immunglobulin of human origin (RIGH). When heterologous antiserum from horse or mule and any rabies vaccine is used for passive-active immunization, a pronounced interfering effect is observed, depending upon the relative concentrations of preformed rabies antibodies given and rabies virus antigen of the vaccines. When 20 IU/kg bwt of RIGH were applied simultaneously with vaccine on day 0 followed by a full series of post-exposure anti-rabies treatment, i.e. 6 doses of vaccine at days 0, 3, 7, 14, 30 and 90, no interference phenomenon was observed, as indicated by an additive effect between passive antibody and actively produced antibody. This was reflected by the observed increase of rabies antibody titre on day 7 post-vaccination and could be demonstrated in three different assays (MNT, CFT and HIT). From day 14 to day 90, no significant difference as to logarithmic increase, plateau formation and persistence of neutralizing and HI antibodies was observed between the serovaccinated and the control group. Serum samples obtained on day 455 from 12 individuals representing both study groups revealed comparable antibody values as assayed in the MNT or HIT respectively. Thus persistence and quantity of vaccine induced antibody to rabies virus, whether produced after plain vaccination or under sero-vaccination conditions, actually show no difference.