NEUTRALIZING AND COMPLEMENT-FIXING ANTIBODY-RESPONSES IN PRE-EXPOSURE AND POST-EXPOSURE VACCINEES TO A RABIES VACCINE PRODUCED IN HUMAN DIPLOID CELLS

Individuals (283) who were probably exposed to rabies were immunized pre- and post-exposure according to different schedules with a .beta.-propiolactone-inactivated and concentrated rabies vaccine prepared in a human diploid cell strain. The vaccine was well tolerated and no major side effects were observed after primary immunization with 3-6 doses. The dynamics of neutralizing and complement-fixing antibody formation and the persistence of antibodies in 3 different groups of 89 vaccinees are described. The groups were vaccinated as follows: (I) pre-exposure on days 0, 28 and 56 (13 individuals); (II) on days 0, 7 and 14 (46 individuals), respectively, and 1 group of 30 individuals was vaccinated post-exposure on days 0, 3, 7, 14, 30 and 90. High levels of neutralizing and complement-fixing antibodies were obtained in all 3 groups and they persisted in the pre-exposure group I as well as in the post-exposure group for at least 18 mo. after initiation of vaccination. With the vaccine under study, the post-exposure vaccination schedule appears to be satisfactory. The complement-fixation test, using a concentrated and purified virion antigen, was highly specific for the follow-up of rabies virus antibody formation in vaccination subjects. Since the complement-fixing and neutralizing rabies virus antibodies were both associated with protection, the complement-fixation test could replace the laborious, time-consuming and expensive neutralization test for such studies.