Development of an attenuated mumps virus vaccine. II. Immune response of animals to vaccination with inactivated and live attenuated mumps viruses.

The immunogenicity and virulence of mumps viruses for mammals decreases during adaptation to growth of the virus in avian cells. However, mumps viruses grown for more than 30 passages in embryonated hen's eggs and/or CEF cell cultures can still infect mammalian cells in culture and alter the immune status of guinea pigs by infecting them. The immune responses of guinea pigs to even the most attenuated mumps viruses are qualitatively different from the responses to inactivated mumps viruses.