Specific antibody patterns over a two-year period after rubella immunization with RA 27/3 live attenuated vaccine

Randomised double-blind placebo-controlled study on adverse effects of rubella immunisation in seronegative women

BACKGROUND

The objective of our study was to investigate the association of adverse clinical musculoskeletal and neurological events in healthy postpartum women with live attenuated (RA27/3 strain) rubella-virus vaccine, and to assess the frequency of acute and recurrent arthralgia and arthritis and associations with acute and recurrent muscle pain (myalgia) and neurological manifestations (paraesthesias).

METHODS

We used a randomised placebo-controlled, double-blind design in a community setting. 636 women were enrolled and, after 90 women dropped out, 546 healthy women aged 18-41 years, who were rubella seronegative on routine screening were immunised parenterally with either monovalent live attenuated (RA27/3 strain) rubella vaccine (n = 270) or saline placebo (n = 276) in the postpartum period. Outcome measures were the occurrence of acute and persistent or recurrent joint manifestations (arthralgia or arthritis) at 1, 3, 6, 9, and 12 months after immunisation. Occurrence of muscle pain (myalgia), and neurological symptoms (paraesthesia) was also assessed at the same times.

FINDINGS

543 women completed 1-month follow-up. 456 women completed the 12-month assessment. There were no differences at the time of immunisation between rubella vaccine and placebo groups in distribution of age, ethnic origin, parity, time between delivery and immunisation, breastfeeding history, or histories of earlier rubella vaccination or joint complaints. Results indicated a significantly higher incidence (p = 0.006; odds ratio = 1.73 [95% CI = 1.17-2.57]) of acute joint manifestations in rubella-vaccine recipients (30%) than in placebo recipients (20%). Frequency of chronic (recurrent) arthralgia or arthritis was only marginally significant (p = 0.042; 1.58 [1.01-2.45]).

INTERPRETATION

RA27/3 rubella vaccine given to seronegative women during the postpartum period was significantly associated with development of acute arthralgia or arthritis. Although the numbers of women assessed and length of follow-up revealed only marginally significant differences in persistent or recurrent joint manifestations between rubella vaccine and placebo recipients, it is possible that susceptible women who are given rubella vaccination may experience this outcome.

Identification of immunoreactive regions of rubella virus E1 and E2 envelope proteins by using synthetic peptides

Relatively large (16-33 aa) synthetic peptides (SPs) representing defined sequences of rubella virus (RV) E1 and E2 envelope proteins were used in lymphocyte stimulation and enzyme immunoassays to map immunoreactive regions recognized by peripheral blood mononuclear cells (PBMNC) and serum antibodies from healthy RV-seropositive, RV-seronegative, and RV-vaccinated adults. Five distinct immunoreactive regions were identified in RV E1 protein, spanning residues (11-39), (154-179), (199-239), (226-277), and (389-412), which stimulated cellular responses in 29-83% of the subjects tested. Two SPs, E1(213-239) and E1(258-277) containing previously-identified virus neutralizing antibody domains, reacted with serum antibodies and also stimulated lymphoproliferation suggesting that these E1 sequences contain linked or overlapping B-and T-cell antigenic sites. The frequency and magnitude of cellular responses to E2 SPs were somewhat lower. SPs encompassing E2 residues (50-72), (140-199), and (244-263) stimulated lymphocyte responses in 28-64% of the subjects tested, while to a lesser degree, SPs within residues (1-36) were also stimulatory. E2 SPs within the regions (1-36), (151-170), and (244-263) also showed low levels of antibody reactivity with sera from RV-seropositive subjects. E2(244-263) which induced the highest level of response among the E2 SPs tested, was of interest due to previous reports of sequence homology of this RV region with human myelin and its potential immunopathogenic role in demyelinating autoimmune diseases. Identification of these potentially immunodominant regions of RV envelope proteins is an important first step in the rational design of new RV vaccines.

Possibility of reinfection after immunisation with RA27/3 live attenuated rubella virus

A serological study was carried out on 527 girls immunized with RA 27/3 rubella vaccine. Data from all scheduled serum samples over a 5-year follow-up were available for 102 vaccinees, 10 (9.8%) of whom showed evidence of reinfection during the 5th year after immunisation, a year in which there was a rubella outbreak in the Siena area (Italy). We examined in greater detail the serological responses of these vaccinees after reinfection and the consequent implications pertinent to the duration of the protective immunity.

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.

Antibody response to wild rubella virus structural proteins following immunization with RA 27/3 live attenuated vaccine

Antibody response to individual structural proteins (E1, E2, and C) of the M-33 wild rubella virus strain was assayed by an immunoblot technique in 12 girls, following immunization with RA 27/3 live attenuated rubella vaccine. Of the 12 immunized subjects, before vaccination 9 had no demonstrable rubella specific antibodies while the remaining 3 had a low level of rubella specific antibodies, reacting only with the E1 protein. At one month after vaccination all the immunized subjects presented anti-E1, anti-E2, and anti-C specific antibodies. However, at 1-2 weeks after vaccination the 9 girls who were seronegative before immunization still had no detectable antibodies to any of the rubella virus structural proteins, while the 3 subjects whose preimmunization sera had reacted with the E1 protein presented an accelerated immune response, showing anti-E2 and anti-C specific antibodies and a more intensely marked anti-E1 specific band.