scholarly journals Consistent Cytotoxic-T-Lymphocyte Targeting of Immunodominant Regions in Human Immunodeficiency Virus across Multiple Ethnicities

2004 ◽  
Vol 78 (5) ◽  
pp. 2187-2200 ◽  
Author(s):  
Nicole Frahm ◽  
B. T. Korber ◽  
C. M. Adams ◽  
J. J. Szinger ◽  
R. Draenert ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
Peptide Sequence ◽  
Immune Recognition ◽  
Cell Responses ◽  
Clade B ◽  
Immunodeficiency Virus

ABSTRACT Although there is increasing evidence that virus-specific cytotoxic-T-lymphocyte (CTL) responses play an important role in the control of human immunodeficiency virus (HIV) replication in vivo, only scarce CTL data are available for the ethnic populations currently most affected by the epidemic. In this study, we examined the CD8+-T-cell responses in African-American, Caucasian, Hispanic, and Caribbean populations in which clade B virus dominates and analyzed the potential factors influencing immune recognition. Total HIV-specific CD8+-T-cell responses were determined by enzyme-linked immunospot assays in 150 HIV-infected individuals by using a clade B consensus sequence peptide set spanning all HIV proteins. A total of 88% of the 410 tested peptides were recognized, and Nef- and Gag-specific responses dominated the total response for each ethnicity in terms of both breadth and magnitude. Three dominantly targeted regions within these proteins that were recognized by >90% of individuals in each ethnicity were identified. Overall, the total breadth and magnitude of CD8+-T-cell responses correlated with individuals' CD4 counts but not with viral loads. The frequency of recognition for each peptide was highly correlated with the relative conservation of the peptide sequence, the presence of predicted immunoproteasomal cleavage sites within the C-terminal half of the peptide, and a reduced frequency of amino acids that impair binding of optimal epitopes to the restricting class I molecules. The present study thus identifies factors that contribute to the immunogenicity of these highly targeted and relatively conserved sequences in HIV that may represent promising vaccine candidates for ethnically heterogeneous populations.

scholarly journals Potentially Exposed but Uninfected Individuals Produce Cytotoxic and Polyfunctional Human Immunodeficiency Virus Type 1-Specific CD8+ T-Cell Responses Which Can Be Defined to the Epitope Level

2008 ◽  
Vol 15 (11) ◽  
pp. 1745-1748 ◽  
Author(s):  
A. L. Erickson ◽  
C. B. Willberg ◽  
V. McMahan ◽  
A. Liu ◽  
S. P. Buchbinder ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
Cell Responses ◽  
Immunodeficiency Virus ◽  
Sex With Men

ABSTRACT We measured CD8+ T-cell responses in 12 potentially exposed but uninfected men who have sex with men by using cytokine flow cytometry. Four of the individuals screened exhibited polyfunctional immune responses to human immunodeficiency virus type 1 Gag or Vif. The minimum cytotoxic T lymphocyte epitope was mapped in one Gag responder.

scholarly journals Human Immunodeficiency Virus-Specific CD8+ T-Cell Responses Do Not Predict Viral Growth and Clearance Rates during Structured Intermittent Antiretroviral Therapy

2002 ◽  
Vol 76 (20) ◽  
pp. 10169-10176 ◽  
Author(s):  
Annette Oxenius ◽  
Angela R. McLean ◽  
Marek Fischer ◽  
David A. Price ◽  
Sarah J. Dawson ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Cd8 T Cell ◽  
Viral Rebound ◽  
Clearance Rates ◽  
Cell Responses ◽  
Treatment Interruptions ◽  
Immunodeficiency Virus

ABSTRACT There is a continuing search for better ways to use existing drugs against human immunodeficiency virus (HIV). One idea is to use short therapy interruptions to “autovaccinate” HIV-infected patients. A group of 13 chronically HIV-infected patients enrolled in a trial of such so-called structured treatment interruptions (STIs) were intensively studied with respect to their viral load (VL) and HIV-specific CD8+ T-cell (cytotoxic T-lymphocyte [CTL]) responses. We found that 10 of the 13 patients had plateau VLs after STIs that were lower than their pretreatment VLs. While viral rebound rates became lower over STIs, there were no changes in clearance rates. Although numbers of CTLs did increase over the same time that viral rebounds decreased, there was no correlation between CTL count and either viral rebound rates or clearance rates. Finally, we asked whether absolute numbers of or changes in numbers of CTLs predict plateau VLs after STIs. No measure of CTLs was able to predict plateau VLs. Thus, there was no signature in these data of an important contribution to virological control from HIV-specific CD8+ T lymphocytes.

scholarly journals Macaques infected long-term with attenuated simian immunodeficiency virus (SIVmac) remain resistant to wild-type challenge, despite declining cytotoxic T lymphocyte responses to an immunodominant epitope

2004 ◽  
Vol 85 (9) ◽  
pp. 2591-2602 ◽  
Author(s):  
Sally A. Sharpe ◽  
Alethea Cope ◽  
Stuart Dowall ◽  
Neil Berry ◽  
Claire Ham ◽  
...  
Keyword(s):  
T Cell ◽  
Simian Immunodeficiency Virus ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
Wild Type ◽  
Immunodominant Epitope ◽  
Cell Responses ◽  
Tetramer Staining ◽  
Immunodeficiency Virus

To further investigate mechanisms of protective immunity that are induced by live, attenuated simian immunodeficiency virus (SIV), three macaques were infected with SIVmacGX2, a nef-disrupted molecular clone. In two of these animals, which expressed the MamuA*01 major histocompatibility complex class I allele, loss of functional activity against an SIV-Gag-encoded immunodominant cytotoxic T lymphocyte (CTL) epitope was observed following prolonged infection. Nonetheless, all three animals were resistant to challenge with an uncloned pool of wild-type SIVmac, whereas four naïve controls became infected. Tetramer staining revealed the rapid generation of CD8+ T-cell responses against gag- and tat-encoded immunodominant epitopes in MamuA*01+ challenge controls. The dynamics of these T-cell responses to the wild-type virus were similar to those observed following primary infection of the vaccine group with attenuated virus. In contrast, neither tetramer staining nor gamma interferon ELISpot assay revealed an immediate, systemic, anamnestic response in the wild-type-challenged, attenuated SIV-infected animals. Functional CTL capacity had not been lost in this group, as lytic activity was still evident 17 weeks after challenge. Both attenuated and wild-type viruses induced a disseminated CD8+ T-cell response, which was of a higher magnitude in lymphoid tissues than in the periphery. These results suggest that, at least as measured in the periphery, protection against wild-type infection that is induced by live, attenuated SIV is not dependent on a rechallenge-driven expansion of immunodominant epitope-specific CD8+ T cells and, therefore, pre-existing activity may be sufficient to prevent superinfection.

scholarly journals Magnitude, Breadth, and Functional Profile of T-Cell Responses during Human Immunodeficiency Virus Primary Infection with B and BF Viral Variants

2008 ◽  
Vol 82 (6) ◽  
pp. 2853-2866 ◽  
Author(s):  
Gabriela Turk ◽  
María Magdalena Gherardi ◽  
Natalia Laufer ◽  
Mónica Saracco ◽  
Renata Luzzi ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
T Cell ◽  
Elispot Assay ◽  
T Cell Responses ◽  
Cell Responses ◽  
Clade B ◽  
Immunodeficiency Virus ◽  
Peptide Level ◽  
Single Peptide

ABSTRACT The molecular pattern of the human immunodeficiency virus (HIV) epidemic in Argentina provides an appropriate scenario to study cellular immune responses in patients with non-clade B infection. We aimed to map T-cell responses in patients infected with BF recombinant variants and compare them with those of clade B patients. Sixteen recently infected patients were enrolled and grouped by viral subtype. Nef-specific responses were evaluated with a peptide matrix-based gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay using B and BF overlapping peptides. Cross-clade and clade-specific responses were found. A correlation between B versus BF Nef-specific responses was identified. Detailed analysis at the single-peptide level revealed that BF patients show a narrower response but greater magnitude. Nef immunodominant responses agreed with previous publications, although the B loop was targeted at an unexpectedly high frequency. The putative HLA allele(s) restricting each positive response was determined. Single-peptide level screening with two different peptide sets uncovered discordant responses (mostly caused by peptide offsetting) and allowed detection of increased breadth. Positive responses identified by ELISPOT assay were further studied by intracellular cytokine staining. These were almost exclusively mediated by CD8 T cells. Characterization of concordant responses revealed that cells show distinct functional profiles, depending on the peptide presented. Last, quality (in terms of polyfunctionality) of T cells was associated with better viral replication containment. Overall, interclade differences in the frequency of epitopes recognized, structural domains targeted, and magnitude of responses were identified. Screening T-cell responses with multiple sets increased sensitivity. Further support for the notion of polyfunctional CD8+ T-cell requirement to better control viral replication is also provided.

scholarly journals Enhanced Detection of Human Immunodeficiency Virus Type 1-Specific T-Cell Responses to Highly Variable Regions by Using Peptides Based on Autologous Virus Sequences

2003 ◽  
Vol 77 (13) ◽  
pp. 7330-7340 ◽  
Author(s):  
Marcus Altfeld ◽  
Marylyn M. Addo ◽  
Raj Shankarappa ◽  
Paul K. Lee ◽  
Todd M. Allen ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Human Immunodeficiency Virus Type ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses ◽  
Clade B ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The antigenic diversity of human immunodeficiency virus type 1 (HIV-1) represents a significant challenge for vaccine design as well as the comprehensive assessment of HIV-1-specific immune responses in infected persons. In this study we assessed the impact of antigen variability on the characterization of HIV-1-specific T-cell responses by using an HIV-1 database to determine the sequence variability at each position in all expressed HIV-1 proteins and a comprehensive data set of CD8 T-cell responses to a reference strain of HIV-1 in infected persons. Gamma interferon Elispot analysis of HIV-1 clade B-specific T-cell responses to 504 overlapping peptides spanning the entire expressed HIV-1 genome derived from 57 infected subjects demonstrated that the average amino acid variability within a peptide (entropy) was inversely correlated to the measured frequency at which the peptide was recognized (P = 6 × 10−7). Subsequent studies in six persons to assess T-cell responses against p24 Gag, Tat, and Vpr peptides based on autologous virus sequences demonstrated that 29% (12 of 42) of targeted peptides were only detected with peptides representing the autologous virus strain compared to the HIV-1 clade B consensus sequence. The use of autologous peptides also allowed the detection of significantly stronger HIV-1-specific T-cell responses in the more variable regulatory and accessory HIV-1 proteins Tat and Vpr (P = 0.007). Taken together, these data indicate that accurate assessment of T-cell responses directed against the more variable regulatory and accessory HIV-1 proteins requires reagents based on autologous virus sequences. They also demonstrate that CD8 T-cell responses to the variable HIV-1 proteins are more common than previously reported.

scholarly journals Maintenance of Viral Suppression in Human Immunodeficiency Virus Controllers Despite Waning T-Cell Responses During Antiretroviral Therapy

2020 ◽  
Vol 222 (11) ◽  
pp. 1837-1842 ◽  
Author(s):  
Nikolaus Jilg ◽  
Pilar Garcia-Broncano ◽  
Michael Peluso ◽  
Florencia P Segal ◽  
Ronald J Bosch ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Antiretroviral Therapy ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Cell Responses ◽  
Immunodeficiency Virus ◽  
Undetectable Viremia ◽  
Hiv Controllers

Abstract AIDS Clinical Trials Group study A5308 found reduced T-cell activation and exhaustion in human immunodeficiency virus (HIV) controllers start antiretroviral therapy (ART). We further assessed HIV-specific T-cell responses and post-ART viral loads. Before ART, the 31% of participants with persistently undetectable viremia had more robust HIV-specific T-cell responses. During ART, significant decreases were observed in a broad range of T-cell responses. Eight controllers in A5308 and the Study of the Consequences of the Protease Inhibitor Era (SCOPE) cohort showed no viremia above the level of quantification in the first 12 weeks after ART discontinuation. ART significantly reduced HIV-specific T-cell responses in HIV controllers but did not adversely affect controller status after ART discontinuation.

scholarly journals Cytotoxic T-Lymphocyte-Associated Antigen 4 (CTLA-4)- and Programmed Death 1 (PD-1)-Mediated Regulation of Monofunctional and Dual Functional CD4+ and CD8+ T-Cell Responses in a Chronic Helminth Infection

2019 ◽  
Vol 87 (12) ◽  
Author(s):  
Anuradha Rajamanickam ◽  
Saravanan Munisankar ◽  
Chandrakumar Dolla ◽  
Thomas B. Nutman ◽  
Subash Babu
Keyword(s):  
T Cell ◽  
T Lymphocyte ◽  
Helminth Infection ◽  
Cytotoxic T Lymphocyte ◽  
T Cell Responses ◽  
Content Type ◽  
Cell Responses ◽  
Dual Functional ◽  
Programmed Death ◽  
Programmed Death 1

ABSTRACT Chronic helminth infections are known to be associated with the modulation of antigen-specific T-cell responses. Strongyloides stercoralis infection is characterized by the downmodulation of antigen-specific Th1 and Th17 responses and the upregulation of Th2 and Th9 responses. Immune homeostasis is partially maintained by negative regulators of T-cell activation, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1), which dampen effector responses during chronic infections. However, their roles in S. stercoralis infection are yet to be defined. Therefore, we sought to determine the role of CTLA-4 and PD-1 in regulating CD4+ and CD8+ T-cell responses and examined the frequencies of monofunctional and dual functional Th1/T cytotoxic type 1 (Tc1), Th17/Tc17, Th2/Tc2, and Th9/Tc9 cells in S. stercoralis infection in 15 infected individuals stimulated with parasite antigen following CTLA-4 or PD-1 blockade. Our data reveal that CTLA-4 or PD-1 blockade results in significantly enhanced frequencies of monofunctional and dual functional Th1/Tc1 and Th17/Tc17 cells and, in contrast, diminishes the frequencies of monofunctional and dual functional Th2/Tc2 and Th9/Tc9 cells with parasite antigen stimulation in whole-blood cultures. Thus, we demonstrate that CTLA-4 and PD-1 limit the induction of particular T-cell subsets in S. stercoralis infection, which suggests the importance of CTLA-4 and PD-1 in immune modulation in a chronic helminth infection.

scholarly journals Differential Pathogen-Specific Immune Reconstitution in Antiretroviral Therapy-Treated Human Immunodeficiency Virus-Infected Children

2019 ◽  
Vol 219 (9) ◽  
pp. 1407-1417 ◽  
Author(s):  
Maximilian Muenchhoff ◽  
Emily Adland ◽  
Julia Roider ◽  
Henrik Kløverpris ◽  
Alasdair Leslie ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cell ◽  
Antiretroviral Therapy ◽  
Immune Reconstitution ◽  
T Cell Responses ◽  
Cell Phenotype ◽  
Memory Phenotype ◽  
Cell Responses ◽  
Immune Exhaustion ◽  
Immunodeficiency Virus

Abstract Background Susceptibility to coinfections in human immunodeficiency virus (HIV)-infected patients remains increased despite antiretroviral therapy (ART). To elucidate mechanisms involved in immune reconstitution, we studied immune activation, immune exhaustion, and HIV- and copathogen-specific T-cell responses in children before and after ART. Methods We prospectively enrolled 25 HIV-infected children to study HIV-, cytomegalovirus (CMV)-, and tuberculosis (TB)-specific T-cell responses before and 1 year after initiation of ART using intracellular cytokine (interleukin-2, interferon-γ, tumor necrosis factor-α) staining assays after in vitro stimulation. We further measured expression of activation, immune exhaustion, and memory phenotype markers and studied proliferative responses after antigen stimulation. Results We observed differential, pathogen-specific changes after 1 year of ART in cytokine profiles of CD4 T-cell responses that were associated with shifts in memory phenotype and decreased programmed cell death 1 (PD-1) expression. The proliferative capacity of HIV- and PPD-specific responses increased after 1 year of ART. Of note, the recovery of CMV- and TB-specific responses was correlated with a decrease in PD-1 expression (r = 0.83, P = .008 and r = 0.81, P = .0007, respectively). Conclusions Reconstitution of immune responses on ART is associated with alterations in T-cell phenotype, function, and PD-1 expression that are distinct for HIV, TB, and CMV. The PD-1 pathway represents a potential target for immunotherapy in HIV-infected patients on ART with insufficient immune reconstitution.

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