The role of MHC class I allele Mamu-A*07 during SIV(mac)239 infection

Immunogenetics. 2011 Dec;63(12):789-807. doi: 10.1007/s00251-011-0541-9. Epub 2011 Jul 6.

Abstract

Virus-specific CD8(+) T cells play an important role in controlling HIV/SIV replication. These T cells recognize intracellular pathogen-derived peptides displayed on the cell surface by individual MHC class I molecules. In the SIV-infected rhesus macaque model, five Mamu class I alleles have been thoroughly characterized with regard to peptide binding, and a sixth was shown to be uninvolved. In this study, we describe the peptide binding of Mamu-A1*007:01 (formerly Mamu-A*07), an allele present in roughly 5.08% of Indian-origin rhesus macaques (n = 63 of 1,240). We determined a preliminary binding motif by eluting and sequencing endogenously bound ligands. Subsequently, we used a positional scanning combinatorial library and panels of single amino acid substitution analogs to further characterize peptide binding of this allele and derive a quantitative motif. Using this motif, we selected and tested 200 peptides derived from SIV(mac)239 for their capacity to bind Mamu-A1*007:01; 33 were found to bind with an affinity of 500 nM or better. We then used PBMC from SIV-infected or vaccinated but uninfected, A1*007:01-positive rhesus macaques in IFN-γ Elispot assays to screen the peptides for T-cell reactivity. In all, 11 of the peptides elicited IFN-γ(+) T-cell responses. Six represent novel A1*007:01-restricted epitopes. Furthermore, both Sanger and ultradeep pyrosequencing demonstrated the accumulation of amino acid substitutions within four of these six regions, suggestive of selective pressure on the virus by antigen-specific CD8(+) T cells. Thus, it appears that Mamu-A1*007:01 presents SIV-derived peptides to antigen-specific CD8(+) T cells and is part of the immune response to SIV(mac)239.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Animals
  • CD8-Positive T-Lymphocytes / immunology*
  • Epitopes, T-Lymphocyte* / analysis
  • Epitopes, T-Lymphocyte* / chemistry
  • Epitopes, T-Lymphocyte* / immunology
  • Genes, MHC Class I / genetics*
  • Histocompatibility Antigens Class I / analysis
  • Histocompatibility Antigens Class I / genetics*
  • Histocompatibility Antigens Class I / immunology
  • Interferon-gamma
  • Macaca mulatta
  • Protein Binding
  • RNA, Viral / blood
  • RNA, Viral / genetics
  • Sequence Analysis, Protein
  • Simian Acquired Immunodeficiency Syndrome / immunology*
  • Simian Immunodeficiency Virus / classification
  • Simian Immunodeficiency Virus / immunology*
  • Simian Immunodeficiency Virus / pathogenicity
  • T-Lymphocytes, Cytotoxic / immunology
  • Viral Load
  • Viral Vaccines

Substances

  • Epitopes, T-Lymphocyte
  • Histocompatibility Antigens Class I
  • RNA, Viral
  • Viral Vaccines
  • Interferon-gamma