Effect of epitope flanking residues on the presentation of N-terminal cytotoxic T lymphocyte epitopes.
We here demonstrate that placing two distinct influenza virus nucleoprotein epitopes at the N terminus of a cytosolic protein selectively blocks their presentation to specific cytotoxic T lymphocytes. The block is a cytosolic phenomenon, which can be overcome by distancing the epitope from the protein N terminus by two or more amino acids. Shortening the protein's C terminus fails to relieve the antigen presentation block. These results demonstrate that events at the N terminus of the target protein, rather than at its C terminus, are responsible for the lack of presentation of N-terminal epitopes. We also show that lack of presentation of N terminal epitopes is associated with a modification of the target protein which affects its electrophoretic mobility and isoelectric focusing point. This modification can be prevented by mutating the epitope's N-terminal flanking sequence, which results in an efficient presentation of the N-terminal epitope. Lack of presentation of the N-terminal epitopes results in a reduced ability of influenza-primed mice to clear acute infection with vaccinia virus encoding an N-terminal nucleoprotein epitope. Our results demonstrate that presentation of epitopes localized at the N terminus of cytosolic proteins can be modulated by events occurring at early stages of antigen processing.
Gileadi
U
U
Institute of Molecular Medicine, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, GB.
Gallimore
A
A
Van der Bruggen
P
P
Cerundolo
V
V
D000818:Animals; D017951:Antigen Presentation; D000941:Antigens / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014616:Vaccinia virus / Q000235:genetics
D000941:Antigens; D017931:DNA Primers; D000939:Epitopes