The High Frequency Indian Rhesus Macaque MHC Class I Molecule, Mamu-B*01, Does Not Appear to Be Involved in CD8+ T Lymphocyte Responses to SIVmac239

Abstract

Although the SIV-infected Indian rhesus macaque (Macaca mulatta) is the animal model most widely used for studying HIV infection, our current understanding of the functional macaque MHC class I molecules is limited. To date, SIV-derived CD8+ T lymphocyte epitopes from only three high frequency macaque MHC class I molecules have been extensively characterized. In this study, we defined the peptide-binding properties of the high frequency Indian rhesus macaque class I molecule, Mamu-B*01 (∼26%). We first identified a preliminary binding motif by eluting and sequencing endogenously bound Mamu-B*01 ligands. We further characterized the peptide-binding characteristics using panels of single amino acid substitution analogs. Using this detailed motif, 507 peptides derived from SIVmac239 were identified and tested for their Mamu-B*01 binding capacity. Surprisingly, only 11 (2.2%) of these motif-containing peptides bound with IC50 values ≤500 nM. We assessed the immunogenicity of these peptides using freshly isolated PBMC from ten Mamu-B*01+ SIV-infected rhesus macaques in IFN-γ ELISPOT and IFN-γ/TNF-α intracellular cytokine staining assays. Lymphocytes from these SIV-infected macaques responded to none of these peptides. Furthermore, there was no sequence variation indicative of escape in the regions of the virus that encoded these peptides. Additionally, we could not confirm previous reports of SIV-derived Mamu-B*01-restricted epitopes in the Env and Gag proteins. Our results suggest that the high frequency MHC class I molecule, Mamu-B*01, is not involved in SIV-specific CD8+ T lymphocyte responses.

Mhc class I haplotypes associated with survival time in simian immunodeficiency virus (SIV)-infected rhesus macaques

“…In the case of Mamu-B*01, this concurs with previous reports. 25,40 Other sequences have been reported to be expressed only at low levels, such as Mamu-B*57 and -A*1303. 24 Taken together, we have identified for the first time Mhc class I haplotypes associated with rapid disease progression.…”

Vaccine-Elicited Mucosal and Systemic Antibody Responses Are Associated with Reduced Simian Immunodeficiency Viremia in Infant Rhesus Macaques

“…Snap-frozen splenic cell pellets were typed for the common MHC class I variants Mamu-A*01, -A*02, -A*08, -A*11, -B*01, -B*03, -B*04, -B*08, and -B*17, chosen for their possible roles in restricting SIV infection and/or control of viremia. Genotyping was completed by the MHC Genotyping Service at the University of Miami Miller School of Medicine, and the established methods have been reported previously (24)(25)(26)(27)(28)(29). Genotypes of the animals are reported in Table 1.…”

Dominant CD8+T-Lymphocyte Responses Suppress Expansion of Vaccine-Elicited Subdominant T Lymphocytes in Rhesus Monkeys Challenged with Pathogenic Simian-Human Immunodeficiency Virus

“…Although the affinity of an epitope peptide for a MHC class I molecule does not always predict the relative dominance of CD8 ϩ T-lymphocyte responses following infection, sufficient binding to MHC class I molecules is required for the stability of peptide-MHC class I complexes and proper peptide presentation on the surface of the antigen-presenting cell. To determine if low-affinity binding of the Env p41A peptide might be associated with the relatively poor expansion of Env p41A-specific CD8 ϩ T-lymphocyte responses to that peptide following SHIV challenge, we assessed the affinity of the Env p41A (YAPPITGQI) and Gag p11C (CTPYDINQM) epitope peptides for Mamu-A*01 by using a cell-free peptide binding assay (22) Mamu-A*01 molecules were incubated with a fixed amount of iodinated indicator peptide and various amounts of the cold competitor peptides Env p41A and Gag p11C or an irrelevant peptide control. These mixtures were assessed for residual I 125 indicator-MHC class I complexes, and any decreases in counts were expressed as percent inhibition at the tested concentration of cold peptide (Fig.…”