Immune responses to wild and vaccine rubella viruses after rubella vaccination

Antibody responses to individual structural proteins (E1, E2, and C) of the M33 wild rubella virus and the RA 27/3 live attenuated rubella strain were assayed by immunoblotting in 11 girls, following immunization with RA 27/3 rubella vaccine. Serum samples were drawn before immunization and at 10 days, 1 month, 1 year, 2 years, and 3 years afterwards. All the subjects showed antibodies to E1 glycoprotein of both the virus strains up to three years after immunization, indicating the importance of E1 in immunity. Antibodies to E1 were always present when with neutralizing activity was observed. Antibodies to E2 protein of both the viruses and to the C protein of the M33 virus gradually disappeared with time in some samples, while antibodies to C protein of the RA 27/3 virus strain were found persistently in all the sera.