Mutually exclusive T-cell receptor induction and differential susceptibility to human immunodeficiency virus type 1 mutational escape associated with a two-amino-acid difference between HLA class I subtypes

Abstract

The relative contributions of HLA alleles and T-cell receptors (TCRs) to the prevention of mutational viral escape are unclear. Here, we examined human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) T-cell responses restricted by two closely related HLA class I alleles, B*5701 and B*5703, that differ by two amino acids but are both associated with a dominant response to the same HIV-1 Gag epitope KF11 (KAFSPEVIPMF). When this epitope is presented by HLA-B*5701, it induces a TCR repertoire that is highly conserved among individuals, cross-recognizes viral epitope variants, and is rarely associated with mutational escape. In contrast, KF11 presented by HLA-B*5703 induces an entirely different, more heterogeneous TCR beta-chain repertoire that fails to recognize specific KF11 escape variants which frequently arise in clade C-infected HLA-B*5703(+) individuals. These data show the influence of HLA allele subtypes on TCR selection and indicate that extensive TCR diversity is not a prerequisite to prevention of allowable viral mutations.

FIG. 1.

Frequency of KF11 mutations in HIV-1 clade B- and clade C-infected individuals. Data are from clade C-infected individuals recruited from South Africa and India (A) and from clade B-infected persons from the United States and Europe (B). (C) HIV-1 RNA of clade C-infected HLA-B*5703-expressing individuals with KF11 wt, A2G-S4(N/K), or A2(G/S/N) sequences.

FIG. 2.

Cross-recognition of KF11 peptide variants in HLA-B*5701- or -B*5703-expressing individuals. (A and B) KF11 variants with amino acid substitutions at position 2, positions 2 and 4, or positions 3, 5, 7, or 10 were tested for recognition in a representative person expressing HLA-B*5701 (A) or HLA-B*5703 (B). (C) Cross-recognition of KF11 variants with single position 2 or combined position 2 and 4 mutations in individuals expressing HLA-B*5701 (seven of the patients described in Table 2 for whom sufficient PBMC samples were available) or HLA-B*5703 (eight of the patients described in Table 2 for whom sufficient samples were available). *, no IFN-γ secretion was observed at the highest peptide concentration tested.

FIG. 3.

Presentation of KF11 peptide variants on HLA-B*5701- and -B*5703-expressing antigen-presenting cells. (A) Target cell lysis of HLA-B*5701- or -B*5703-expressing B-LCL pulsed with KF11 wild type or variant peptides following exposure to a KF11-specific CD8⁺ T-cell clone restricted to HLA-B*5701 (Vβ19-CASTGTYGYT-J1.2; Vα5-CAASGGYQKVTFGTGTKLQVIP). (B) Drop-off rate of KF11 peptide variants from HLA-B*5701- or -B*5703-expressing B-LCL. Target cell lysis of HLA-B*5701- or -B*5703-expressing B-LCL by an HLA-B*5701-restricted CD8⁺ T-cell clone was measured either immediately after peptide pulsing (0 h) or after 12 or 36 h of resting. One representative experiment out of three is shown. (C) Proliferative responses of B*5701- or B*5703-restricted KF11-specific CD8⁺ T cells to stimulation with KF11 wt or KF11 A2G-S4(N/K) peptides, as measured by CFSE dilution assays. The right column indicates proliferative responses of HLA-B*5701-restricted KF11-specific CD8⁺ T cells stimulated with KF11 wt peptide or KF11 A2G-S4(N/K) peptide presented by B*5703-restricted B-LCL.

FIG. 3.

Presentation of KF11 peptide variants on HLA-B*5701- and -B*5703-expressing antigen-presenting cells. (A) Target cell lysis of HLA-B*5701- or -B*5703-expressing B-LCL pulsed with KF11 wild type or variant peptides following exposure to a KF11-specific CD8⁺ T-cell clone restricted to HLA-B*5701 (Vβ19-CASTGTYGYT-J1.2; Vα5-CAASGGYQKVTFGTGTKLQVIP). (B) Drop-off rate of KF11 peptide variants from HLA-B*5701- or -B*5703-expressing B-LCL. Target cell lysis of HLA-B*5701- or -B*5703-expressing B-LCL by an HLA-B*5701-restricted CD8⁺ T-cell clone was measured either immediately after peptide pulsing (0 h) or after 12 or 36 h of resting. One representative experiment out of three is shown. (C) Proliferative responses of B*5701- or B*5703-restricted KF11-specific CD8⁺ T cells to stimulation with KF11 wt or KF11 A2G-S4(N/K) peptides, as measured by CFSE dilution assays. The right column indicates proliferative responses of HLA-B*5701-restricted KF11-specific CD8⁺ T cells stimulated with KF11 wt peptide or KF11 A2G-S4(N/K) peptide presented by B*5703-restricted B-LCL.

FIG. 4.

Presentation of naturally processed KF11 peptide variants on HLA-B*5701- and -B*5703-expressing B-LCL. IFN-γ secretion by the same HLA-B*5701-restricted KF11-specific CD8⁺ T-cell clone was analyzed after stimulation with HLA-B*5701- or -B*5703-expressing B-LCL infected with vaccinia virus constructs encoding different KF11 variant sequences. In each case, one representative example with an effector:target ratio of 10:1 is shown.