IDENTIFICATION OF HELPER T-CELL ANTIGENIC SITES IN MICE FROM THE HEMAGGLUTININ GLYCOPROTEIN OF MEASLES-VIRUS

The aim of this study was to define the helper T cell epitopes on the haemagglutinin (H) of measles virus (MV) in BALB/c (H-2(d)) and TO (H-2(s)) mice. A panel of 55 synthetic peptides (15-mers, overlapping by five amino acids) representing 92.2 % of the H protein were synthesized and tested for immunogenicity and ability to stimulate MV-primed lymphocytes in vitro. The results obtained show that mouse lymphocytes respond to defined regions of the H protein which differ according to mouse strain. Virus-primed lymphocytes from BALB/c mice responded in vitro to peptides 7, 38, 39 and 44 whereas lymphocytes from virus-primed TO mice responded only to peptide 39. When mice of both strains were immunized with the peptides, a number of peptides induced proliferative responses, showing that the T cell repertoire for epitopes on the H protein is broader than that following immunization with virus. In BALB/c mice. lymphocytes primed to peptides 37. 39, 40. 42 and 43 responded in vitro to MV and in TO mice, lymphocytes primed to peptides 14. 32, 39, 40 and 49 responded to the virus. Thus in both strains of mice peptide 39 behaved as a dominant T cell epitope following immunization with virus or peptides. When the results obtained experimentally were compared with sequences predicted to be T cell epitopes by a number of algorithms, the concordance was limited.