Characterization of T cell epitopes in measles virus nucleoprotein

T cell epitopes of the measles virus (MV) nucleoprotein were studied by synthesizing overlapping 20 aa peptides over the known sequence of the protein and analysing the proliferation responses of a panel of MV-specific T cell lines and clones against these peptides. T cell lines were established from eleven healthy controls and seven multiple sclerosis patients, all with a history of past MV infection. The epitopes recognized by these lines were concentrated in a few regions of the polypeptide chain. Overlapping peptides containing aa 321-340 and 331-350 were most often recognized. Other epitopes were detected close to the amino-terminal end of the polypeptide chain as each of the peptides 1-20, 21-40, 31-50 and 51-70 contained stimulating moieties. Some responses were also detected towards peptides 151-200 and 221-250, but the carboxy-terminal end of the polypeptide was not recognized by any of the tested T cell lines. The amino acid sequences of the peptides that stimulated the T cell clones and lines, as a rule, contained binding motifs described for HLA-DR alleles found in T cell donors. The regions of protein sequence which did not reveal any T cell epitopes were, instead, relatively free of binding motifs. The results suggest that only a few epitopes of the MV nucleoprotein are important in establishing T cell immunity.