1175–1186. 26. Lewicki, H.A., G. von Herrath, C.F. Evans, J.L. Whitton, and M.B. Oldstone. 1995. CTL escape viral variants. II. Biologic activity in vivo. Virology. 211:443–450. 27. van der Most, R.G., R.J. Concepcion, C. Oseroff, J. Alexander, S. Southwood, J. Sidney, R.W. Chesnut, R. Ahmed, and A. Sette. 1997. Uncovering subdominant cytotoxic T-lymphocyte responses in lym- phocytic choriomeningitis virus-infected BALB/c mice. J. Virol. 71: 5110–5114. 28. Stewart-Jones, G.B., A.J. McMichael, J.I. Bell, D.I. Stuart, and E.Y. Jones. 2003. A structural basis for immunodominant human T cell re- ceptor recognition. Nat. Immunol. 4:657–663. 29. Kjer-Nielsen, L., C.S. Clements, A.W. Purcell, A.G. Brooks, J.C. Whisstock, S.R. Burrows, J. McCluskey, and J. Rossjohn. 2003. A structural basis for the selection of dominant alphabeta T cell receptors in antiviral immunity. Immunity. 18:53–64. 30. Turner, S.J., K. Kedzierska, H. Komodromou, N.L. La Gruta, M.A. Dunstone, A.I. Webb, R. Webby, H. Walden, W. Xie, J. McCluskey, et al. 2005. Lack of prominent peptide-major histocompatibility com- plex features limits repertoire diversity in virus-specific CD8 T cell populations. Nat. Immunol. 6:382–389. 31. Salter, R.D., and P. Cresswell. 1986. Impaired assembly and transport of HLA-A and -B antigens in a mutant TxB cell hybrid. EMBO J. 5:943–949. 32. Khanna, R., S.L. Silins, Z. Weng, D. Gatchell, S.R. Burrows, and L. Cooper. 1999. Cytotoxic T cell recognition of allelic variants of HLA B35 bound to an Epstein-Barr virus epitope: influence of peptide confor- mation and TCR-peptide interaction. Eur. J. Immunol. 29:1587–1597. 33. Macdonald, W., D.S. Williams, C.S. Clements, J.J. Gorman, L. Kjer- Nielsen, A.G. Brooks, J. McCluskey, J. Rossjohn, and A.W. Purcell. 2002. Identification of a dominant self-ligand bound to three HLA B44 alleles and the preliminary crystallographic analysis of recombinant forms of each complex. FEBS Lett. 527:27–32. 34. Rossmann, M.G., and C.G. van Beek. 1999. Data processing. Acta Crystallogr. D Biol. Crystallogr. 55:1631–1640. 35. Jones, T.A., J.Y. Zou, S.W. Cowan, and M. Kjeldgaard. 1991. Improved methods for building protein models in electron density maps and the lo- cation of errors in these models. Acta. Crystallogr. A. 47:110–119. 36. Brunger, A.T., P.D. Adams, G.M. Clore, W.L. DeLano, P. Gros, R.W. Grosse-Kunstleve, J.S. Jiang, J. Kuszewski, M. Nilges, N.S. Pannu, et al. 1998. Crystallography & NMR system: a new software suite for macromolecular structure determination. Acta Crystallogr. D Biol. Crystallogr. 54:905–921. 37. Purcell, A.W. 2004. Isolation and characterization of naturally pro- cessed MHC-bound peptides from the surface of antigen-presenting cells. Methods Mol. Biol. 251:291–306. 38. Purcell, A.W., J.J. Gorman, M. Garcia-Peydro, A. Paradela, S.R. Bur- rows, G.H. Talbo, N. Laham, C.A. Peh, E.C. Reynolds, J.A. Lopez de Castro, and J. McCluskey. 2001. Quantitative and qualitative influences of tapasin on the class I peptide repertoire. J. Immunol. 166:1016–1027. 39. Macdonald, W.A., A.W. Purcell, N. Mifsud, L.K. Ely, D.S. Williams, L. Chang, J.J. Gorman, C.S. Clements, L. Kjer-Nielsen, D.M. Koelle, et al. 2003. A naturally selected dimorphism within the HLA-B44 su- pertype alters class I structure, peptide repertoire, and T cell recogni- tion. J. Exp. Med. 198:679–691. 1260 THE INFLUENCE OF PEPTIDE CONFORMATION ON A CYTOTOXIC T CELL RESPONSE | Tynan et al.