Purified chick-embryo-cell (PCEC) rabies vaccine: its potency performance in different test systems and in humans

The potency of purified chick embryo cell rabies vaccine Rabipur was evaluated by four different in vivo test systems: (1) NIH test with homologous strain LEP challenge; (2) intramuscular challenge of vaccinated laboratory animals; (3) postexposure vaccine treatment trials in laboratory animals; and (4) antibody induction tests in laboratory animals. These different test systems were compared with the Standard NIH test and an in vitro test, the modified ABT. Each of the four in vivo methods chosen demonstrated potency values superior to that of the Standard NIH test in which challenge was with CVS strain. Potency relations were: Standard NIH test versus alternative methods versus modified ABT 1.0-2.2-1.85 respectively. There was good correlation between alternative in vivo methods and the ABT. In addition examples of antibody induction in man following administration of various postexposure treatment regimens are presented which lead to the conclusion that postexposure vaccination method and composition of the study group play a more important role in achieving optimum treatment results than vaccine potency, provided that it corresponds to WHO requirements (minimum 2.5 IU per dose).