Definition of three minimal T helper cell epitopes of rubella virus E1 glycoprotein

To characterize T cell-recognized epitopes on rubella virus (RV) E1 glycoprotein, IL-2-dependent RV-specific T cell lines were established from 14 rubella-seropositive healthy donors. The responses of these lines were studied by using a panel of 94 partially overlapping synthetic peptides of 15 amino acids (aa) length covering the known nucleotide sequence of RVE1 glycoprotein. Two to seven peptide-defined epitopes were recognized by the T cell lines, but a large interindividual variation was found. T cell reactivity was most often localized to the regions between aa 276 and 290, aa 381 and 395 and aa 410 and 420. Analysis of overlapping, truncated peptides revealed three minimal T helper cell epitopes VIGSQARK, KFVTAALLN and RVIDPAAQ in aa positions 280-287, 385-393 and 412-419, respectively.