Stability of the rabbit immunogenic marker of RA 27-3 rubella vaccine virus after human passage.

Rabbits were inoculated intravenously with "wild" rubella virus, RA 27/3 rubella vaccine virus, or rubella virus isolated from recipients of RA 27/3 vaccine. Rabbits receiving "wild" virus developed rubella hemagglutination inhibition antibody, and those receiving vaccine virus did not. One of the five reisolates tested produced a low transient antibody response in two of the five rabbits inoculated with this strain. The study indicates that the rabbit immunogenic marker after intravenous injection can be used to determine if a rubella virus isolated from a patient is of "wild" or vaccine origin. There was no significant change in the reduced immunogenicity characteristics of the RA 27/3 vaccine virus after human passage.