ANALYSIS OF A NATURALLY-OCCURRING HLA CLASS I-RESTRICTED VIRAL EPITOPE

A previously described nonapeptide sequence motif for antigens recogni zed by T cells in the context of the human major histocompatibility co mplex (MHC) molecule HLA-A2.1 was used to identify the natural epitope of influenza A virus matrix protein. We show here that the peptide wi th the sequence GILGFVFTL is the synthetic analogue of the natural epi tope by demonstrating the presence of the corresponding peptide on MHC molecules of virus-infected cells. The role of the hydrophobic anchor amino acids in positions 2 and 9, which constitute the epitope motif, was investigated with synthetic variants of the epitope and cytotoxic T lymphocytes as indicator cells. The crucial role of the side chains of amino acids in those positions was evidenced by their influence on the efficiency of T-cell stimulation.