To design a safe and effective synthetic
peptide vaccine against rubella virus (RV)
infection, it is necessary to identify immunodominant
T-cell epitopes of RV structural
proteins. To define such
epitopes, 49 overlapping synthetic
peptides (17-34 residues in length) corresponding to more than 95% of the amino acid sequence of RV virion
proteins E1 (23
peptides) and C (11
peptides) and all of E2 (15
peptides) were synthesized and tested for their capacities to induce proliferative responses of
rubella-specific T-cell lines and T-cell clones derived from 4 study groups (5 women infected with RV in pregnancy, 5 patients with
congenital rubella syndrome, 5 seropositive healthy donors, and 5 RV
vaccine recipients). The most frequently recognized
epitopes were E1-21 (residues 358-377) with 11/20 responders, E2-4 (residues 54-74) with 6/20 responders, and C11 (residues 255-280) with 11/20 responders, respectively. E1-10 (residues 174-193), E1-16 (residues 272-291) and E1-18 (residues 307-326) were responded to strongly by corresponding T-cell clones, and were recognized by 4 or 5 T-cell lines. T-cell lines derived from three
congenital rubella syndrome patients did not respond to any of the synthetic
peptides. The results showed that more
T-cell epitopes were present in E1 (19/23) and C (10/11) than in E2 (8/15). The identification of T cell sites recognized frequently by RV-infected or -immunized populations could provide the basis for selecting candidate
T-cell epitopes for the development of an effective
synthetic vaccine against
rubella.