A naturally processed rat major histocompatibility complex class I-associated viral peptide as target structure of Borna disease virus-specific CD8(+) T cells

The first naturally processed peptide synthesized by a virus and recognized by classical CD8(+) T cells in association with the RT1.A(1) major histoco mpatibility complex class I molecule of the Lewis rat is reported. Borna di sease virus-specific CD8(+) T cells recognize syngeneic target cells pulsed with peptides extracted from Borna disease virus-infected cells. The predi cted peptide sequence ASYAQMTTY from the viral p40 protein coeluted with th e cytotoxic T-lymphocyte-reactive fraction was identified among natural lig ands by tandem mass spectrometry. Numerous naturally processed peptides der ived from intracellular bacteria, viruses, or tumors and recognized by CD8( +) T cells of man and mice are known, leading to a better understanding of cellular immune mechanisms against pathogens in these two species. In contr ast, for the rat little information exists with regard to the function and role of CD8(+) T cells as part of their cellular immune defense system. Thi s first naturally processed viral epitope in the rat contributes to the und erstanding of the rat cellular immune response and might trigger the identi fication of more cytotoxic T-lymphocyte epitopes in this animal.