Definition of an optimal cytotoxic T lymphocyte epitope in the latently expressed Kaposi's sarcoma-associated herpesvirus kaposin protein

Cytotoxic T lymphocytes (CTL) recognize and kill virus-infected cells and c ontribute to immunologic control of viral replication. For many herpesvirus es (e.g., Epstein-Barr and cytomegalovirus), virus-specific CTL responses c an be readily detected in infected persons, but CTL responses against Kapos i's sarcoma-associated herpesvirus (KSHV) appear to be weak and remain poor ly characterized. Using a human leukocyte antigen (HLA) binding motif-based epitope prediction algorithm, we identified 37 HLA-A*0201 binding peptides from 8 KSHV open-reading frames (ORFs). After in vitro stimulation of peri pheral blood mononuclear cells from KSHV-infected persons, CTL responses ag ainst 1 peptide in the KSHV kaposin protein (ORF K12) were detected in 2 HL A-A*0201-positive subjects. The optimal CTL epitope was identified by HLA r estriction analysis and peptide titration assays. These data describe a lat ent phase viral gene product targeted by CTL that may be relevant for KSHV immunopathogenesis.