3 T-CELL EPITOPES WITHIN THE C-TERMINAL 265-AMINO-ACIDS OF THE MATRIXPROTEIN PP65 OF HUMAN CYTOMEGALOVIRUS RECOGNIZED BY HUMAN-LYMPHOCYTES

Although a T-cell response in human cytomegalovirus (HCMV)-immune indi viduals exists against the most abundantly expressed protein pp65 of t he virus matrix, less is known about the determinants that evoke this response. The aim of the study was to identify regions within HCMV pp6 5 (ppUL83) that contain sequences for the cellular immune response by the use of three recombinant overlapping beta-galactosidase pp65 fusio n proteins (C74, C35, and C47), covering the C-terminal 265 amino acid s of the entire pp65 sequence. Two T-cell epitope determinants were re cognized by human lymphocytes of healthy, HCMV-seropositive, human leu kocyte antigen (HLA)-typed individuals. One T-cell determinant (amino acids [aa] 303-388) was localized in the mid-region of the entire pp65 sequence and a second T-cell determinant (aa 477-561) within the C-te rminal region. By fine mapping with synthetic hexadecamer peptides thr ee T-cell epitopes were identified within these two regions: P10-I (aa 361-376) in the mid-region, P3-II (aa 485-499), and P6-II (aa 509-524 ) in the C-terminal region. Inhibition studies with monoclonal antibod ies to HLA class I or class II revealed a class II restricted response to peptides P10-I or P6-II, respectively. P10-I responders shared the HLA-DR11 allele and P6-II responders the -DR3 allele. Therefore, thes e T-cell epitopes of HCMV pp65 might be presented in association with particular HLA class II alleles. (C) 1997 Wiley-Liss, Inc.