Characterization of a new H-2D(k)-restricted epitope prominent in primary influenza A virus infection

Influenza A virus infection of mice has been used extensively as a model to investigate the mechanisms of antigen presentation to cytotoxic T lymphocy tes (CTL) and the phenomenon of immunodominance in antiviral CTL responses. The different virus-encoded epitopes that are recognized in H-2(b) and H-2 (d) mice have been characterized and their relative immunodominance has bee n well-studied. In H-2(k) mice, four different K-k-restricted influenza vir us epitopes have been described, but the dominance hierarchy of these epito pes is unknown and there is also an uncharacterized D-k-restricted response against the virus. In this study, a D-k-restricted epitope derived from th e influenza virus A/PR/8/34 polymerase protein PB1, corresponding to amino acid residues 349-357 (ARLGKGYMF), was identified. This peptide is the majo r epitope within the PB1 polymerase and is at least as dominant as any of t he four K-k-restricted epitopes that are recognized in CBA mice following p rimary influenza virus infection, The PB1 epitope is only the fourth D-k-pr esented peptide to be reported and the sequence of this epitope confirms a D-k-restricted peptide motif, consisting of arginine at position two, argin ine or lysine at position five and a hydrophobic residue at the carboxy ter minus.