Comprehensive Analysis of Human Immunodeficiency Virus Type 1-Specific CD4 Responses Reveals Marked Immunodominance of gag and nef and the Presence of Broadly Recognized Peptides (original) (raw)
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Journal of Virology, 2001
Virus-specific cytotoxic T-lymphocyte (CTL) responses are critical in the control of human immunodeficiency virus type 1 (HIV-1) infection and will play an important part in therapeutic and prophylactic HIV-1 vaccines. The identification of virus-specific epitopes that are efficiently recognized by CTL is the first step in the development of future vaccines. Here we describe the immunological characterization of a number of novel HIV-1-specific, HLA-A2-restricted CTL epitopes that share a high degree of conservation within HIV-1 and a strong binding to different alleles of the HLA-A2 superfamily. These novel epitopes include the first reported CTL epitope in the Vpr protein. Two of the novel epitopes were immunodominant among the HLA-A2restricted CTL responses of individuals with acute and chronic HIV-1 infection. The novel CTL epitopes identified here should be included in future vaccines designed to induce HIV-1-specific CTL responses restricted by the HLA-A2 superfamily and will be important to assess in immunogenicity studies in infected persons and in uninfected recipients of candidate HIV-1 vaccines.
Virology, 2000
We investigated the immune response against a human immunodeficiency virus type 1 (HIV-1) nef DNA sequence administered epidermally in mice transgenic for the human major histocompatibility complex (MHC) class I molecule HLA-A201. Ten potential HLA-A2 binding 9-mer Nef peptides were identified by a computer-based search algorithm. By a cell surface MHC class I stabilization assay, four peptides were scored as good binders, whereas two peptides bound weakly to HLA-A2. After DNA immunization, cytotoxic T lymphocyte (CTL) responses were predominantly directed against the Nef 44-52, 81-89, and 85-93 peptides. Interestingly, the 44-52 epitope resides outside the regions of Nef where previously described CTL epitopes are clustered. Dominance among Nef-derived peptides did not strictly correlate with HLA-A2 binding, in that only one of the high-affinity binding peptides was targeted in the CTL response. The 44-52, 85-93, and 139-147 peptides also generated specific CTLs in response to peptide immunization. T helper cell proliferation was detected after stimulation with 20-mer peptides in vitro. Three Nef regions (16-35, 106-125, and 166-185) dominated the T helper cell proliferation. The implications of these results for the development of DNA-based vaccines against HIV is discussed.
Novel Nested Peptide Epitopes Recognized by CD4+ T Cells Induced by HIV-1 Conserved-Region Vaccines
Vaccines
CD4+ T-cell responses play an important role in the immune control of the human immunodeficiency virus type 1 (HIV-1) infection and as such should be efficiently induced by vaccination. It follows that definition of HIV-1-derived peptides recognized by CD4+ T cells in association with HLA class II molecules will guide vaccine development. Here, we have characterized the fine specificity of CD4+ T cells elicited in human recipients of a candidate vaccine delivering conserved regions of HIV-1 proteins designated HIVconsv. The majority of these 19 most immunogenic regions contained novel epitopes, that is, epitopes not listed in the Los Alamos National Laboratory HIV Sequence Database, which were able in vitro to stimulate vaccinees’ CD4+ T cells to proliferate and produce interferon-γ and tumor necrosis factor-α. Accumulation of HLA class II epitopes will eventually accelerate development of HIV-1 prophylactic and therapeutic vaccines.
Virology, 2007
We previously detected HIV-1 Gag-specific CD4 + T cells recognizing reference strain viral epitopes in subjects with progressive, chronic infection. To test whether these CD4 + T cells persist in vivo by failing to recognize autologous HIV-1 epitopes, we compared autologous plasma HIV-1 p24 nucleotide sequences with targeted HXB.2 strain Gag p24 CD4 + T cell epitopes in nine chronically infected, untreated subjects. In five responding subjects, 10 of 26 HXB.2 strain p24 peptides targeted by CD4 + T cells exactly matched autologous plasma viral sequences. Four subjects with plasma viral loads > 100,000 copies/mL had no measurable p24-specific CD4 + T cell responses despite carrying HIV-1 strains that matched HXB.2 sequences at predicted epitopes. These results show that HIV-1-specific CD4 + T cells can persist in chronic HIV-1 infection despite recognition of epitopes present in vivo. However, with high-level in vivo HIV-1 replication, CD4 + T cells targeting autologous HIV-1 may be non-responsive or absent.
Human immunodeficiency virus type 1 gp120 C5 region mimics the HLA class I α1 peptide-binding domain
European Journal of Immunology, 1993
Molecular mimicry of major histocompatibility (MHC) antigens by viral glycoproteins has been suggested as one of the possible mechanisms of induction of an autoimmune response by human immunodeficiency viruses. A monoclonal antibody (M38) was previously shown to bind to both human immunodeficiency virus type 1 (HIV-1) gp120 and β-2 microglobulin-free HLA class I heavy chains encoded by an HLA C allele. Using HLA C recombinant proteins and synthetic peptides, the M38 class I binding site was mapped to a stretch of 44 amino acids of the al domain. The amino acid residues recognized are clustered in two non-contiguous regions at positions 66-69 (KYKR) and 79-82 (RKLR) shared by almost all HLA C alleles. On HIV-1 gp120, M38 binds to two non-contiguous sequences (KYK and KAKR) at positions 490-492 and 505-508 located at the edges of a large hydrophobic region that is apparently involved in binding the transmembrane glycoprotein gp41. The C-terminal gp120 M38-reactive region (KAKR) lies within the immunodominant sequence APTKAKRRVVQREKR, against which the majority of HIV-infected individuals produce antibodies. The results indicate that a functionally important region of HIV-1 gp120 shares similar amino acid sequence motifs with the antigen recognition site of most HLA class I C alleles. The molecular mimicry may be the basis for autoimmune responses in HIV infection.
Direct interrogation of viral peptides presented by the class I HLA of HIV-infected T cells
Journal of virology, 2014
Identification of CD8(+) cytotoxic T lymphocyte (CTL) epitopes has traditionally relied upon testing of overlapping peptide libraries for their reactivity with T cells in vitro. Here, we pursued deep ligand sequencing (DLS) as an alternative method of directly identifying those ligands that are epitopes presented to CTLs by the class I human leukocyte antigens (HLA) of infected cells. Soluble class I HLA-A*11:01 (sHLA) was gathered from HIV-1 NL4-3-infected human CD4(+) SUP-T1 cells. HLA-A*11:01 harvested from infected cells was immunoaffinity purified and acid boiled to release heavy and light chains from peptide ligands that were then recovered by size-exclusion filtration. The ligands were first fractionated by high-pH high-pressure liquid chromatography and then subjected to separation by nano-liquid chromatography (nano-LC)-mass spectrometry (MS) at low pH. Approximately 10 million ions were selected for sequencing by tandem mass spectrometry (MS/MS). HLA-A*11:01 ligand sequenc...
AIDS Research and Human Retroviruses, 2017
Antibodies to the carboxyterminal constant (C5) region 5 of the HIV-1 envelope glycoprotein gp120 have previously been associated with slow disease progression. This is one of the regions on gp120 that interact with the transmembrane glycoprotein, gp41, anchoring it to the viral and infected cell membrane. This study analyzed humoral responses to a novel heterodimeric peptide construct comprising the C5 501-512 region and a compatible region on gp41 732-744. Antibody levels to C5 501-512 /gp41 732-744 were associated with slow disease progression in a treatment naive historical longitudinal cohort from Norway (n=32; p=0.00001). Elevated anti-C5 501-512 /gp41 732-744 antibody levels correlated with moderate viral load (VL) (50-10,000 copies/mL) in a cohort including natural viral suppressors (NVS) in the Unites States (n=58; p=0.002). Analysis of HIV positive sera from treatment naïve patients in Estonia (n=300) showed an inverse correlation between anti-C5 501-512 /gp41 732-744 antibodies and VL when comparing VL 2000-10,000 copies/mL with VL>10,000 (p=0.050). Further mapping using peptide inhibition of antibody binding revealed that responses to the C5 501-506 subdomain correlated with preserved CD4 counts (n=55; p=0.0012) irrespective of VL in this cohort. The C5 region encompassing C5 501-506 shows sequence similarity to the shared epitope (SE) of certain HLA-DR associated with immune dysfunction. Partial antigenic cross reactivity between SE and C5 is indicated by partial inhibition of NVS antibody binding using SE 15-mer peptide (median 65 % inhibition), the C5 501-506 6-mer peptide (79% inhibition), and binding of rheumatoid arthritis patient sera to both SE and C5 peptide sequences. The potential influence of these observations on HIV-1 pathogenesis remains to be determined.
Immunobiology, 1999
This study was designed to distinguish between antibodies in HIV-l-infected patients directed against epitopes accessible on the native HIV-l envelope (Env) complex and non-native Env epitopes. Peptide p#13 (Env. aa642-673) containing the neutralising 2F5 epitope and recombinant soluble glycoprotein 160 (rsgpI60) were used in ELISA to determine the antibody (Ab) reactivity in sera of 116 HIV-l-infected individuals and 18 HIV negative controls. The reactivity of sera classified CDC stage C against p#13 was significantly decreased in comparison to stage A sera, while staying constant against rsgpl60. Accordingly, in 6 out of 8 individual patients tested over time the response against p#13 was declining at later time points of infection. The reactivity of patients' sera against p#13 corresponded directly to the recognition of infected T cells and largely also to the CD4 cell count. The causal relationships of these phenomena are not clear. It is conceivable that antibodies against epitopes on HIV are lost or escape mutants arise and consequently control of HIV is lost and virus load increases as it is known for CDC stage C. Alternatively, increasing virus load may affect B cells recognising native Env epitopes and turn antibody production down by some mechanism. In this latter scenario helper T cells might have a critical role.
Journal of Immunological Methods, 2010
Identification of CTL epitopes correlated to immune protection is important for the development of vaccines that enhance T cell-mediated immune responses. The correlation of positively selected amino acids (PS) of HIV-1 with host HLA alleles can identify regions containing potential T cell epitopes. However, the specific epitopes have to be identified and characterized using overlapping peptides through T cell functional assays. In this study we used a new approach to identify and characterize potential epitopes in the gag region containing PS mutations that significantly correlated with HLA-A*0301. The iTopia Epitope Discovery System was used to rapidly screen a panel of peptides overlapping the regions containing PS mutations and the peptides identified were assessed for relative affinity and complex stability. The potential epitopes were then validated by interferon gamma (IFN-γ) ELISpot assays with patient PBMCs. Using this approach we identified/confirmed the predicted HLA-A*0301 epitopes in two regions of gag containing PS mutations V7I and K403R, one previously reported and the other novel. Five of the seven peptides that bound to A*0301 contained the K403R mutation and corresponded to the documented LARNCRAPRK-A3 supertype epitope. Two epitope variants, RASVLSGGK and RASILSGGK containing the V7I mutation, were identified using the iTopia Epitope Discovery System, however only the consensus variant (RAK9C) was confirmed using the ELISpot assay and it represents a novel A*0301 epitope.