Measles virus antigens induce both type-specific and canine distemper virus cross-reactive cytotoxic T lymphocytes in mice: localization of a common Ld-restricted nucleoprotein epitope

We have studied the induction of the cytotoxic T lymphocyte (CTL) response to measles virus (MV) antigens expressed as vaccinia virus (VV) recombinants in a murine model. In C3H mice (H-2k) only the nucleoprotein (NP) induced a CTL response and this was shown to be cross-reactive with the closely related canine distemper virus (CDV). The presentation of this antigen was shown to be Kk-restricted. In BALB/c mice (H-2d), both the haemagglutinin (HA) and the NP induced a strong CTL response, the former being serotype-specific, whereas the latter cross-reacted with CDV. Both responses were found to be Ld-restricted. Based on the prediction for Ld T cell motifs, we tested a number of MV NP-derived nonapeptides for their capacity to sensitize P815 cells (H-2d) for lysis by spleen cells from VV-NP-immunized mice. One of these peptides, comprising amino acids 281 to 289 (Tyr-Pro-Ala-Leu-Gly-Leu-His-Glu-Phe) was as effective as cells expressing the complete NP protein. This motif is conserved in the CDV NP.