HLA-A1 AND HLA-A3 T-CELL EPITOPES DERIVED FROM INFLUENZA-VIRUS PROTEINS PREDICTED FROM PEPTIDE BINDING MOTIFS

The potential value of peptide binding motifs of HLA class I molecules for the prediction of viral epitopes presented to T cells has been an alyzed for two common HLA alleles. CTL generated against type A influe nza virus recognize peptide epitopes derived from the nucleoprotein (N P) and basic polymerase 1 presented by HLA-A1, and epitopes derived fr om NP presented by HLA-A3. Distinct peptide binding motifs with charac teristic anchor residues were previously identified for each of these class I molecules based on the sequences of endogenous peptides: for H LA-A1, position 3 = Asp or Glu and position 9 = Tyr; for HLA-A3, posit ion 2 = Leu and position 9 = Lys or Tyr. Six peptides containing the H LA-A1 binding motif were identified within the sequences of the NP and basic polymerase 1 proteins, and one peptide containing the HLA-A3 mo tif was identified in the NP molecule. Three of the six HLA-A1 peptide s and the one HLA-A3 NP peptide could bind to HLA-A1 or HLA-A3, respec tively, in an in vitro peptide binding assay. Two of the HLA-A1-bindin g peptides could sensitize target cells for lysis by influenza virus-i mmune CTL populations restricted by HLA-A1 (NP 44-52 CTELKLSDY and PB1 591-599 VSDGGPNLY), and the one HLA-A3 NP peptide (NP 265-273 ILRGSVA HK) could sensitize target cells for lysis by HLA-A3-restricted influe nza-immune CTL. Each peptide was also shown to be able to induce pepti de-specific class I-restricted CTL in vitro, and the CTL generated aga inst two of these peptides could specifically recognize virus-infected targets. Thus, these peptide binding motifs can be used to construct immunogenic synthetic epitopes which are capable of inducing antiviral T cell-mediated immune responses.