CD8+ T Cell Cross-Reactivity Profiles and HIV-1 Immune Escape towards an HLA-B35-Restricted Immunodominant Nef Epitope

Antigen cross-reactivity is an inbuilt feature of the T cell compartment. However, little is known about the flexibility of T cell recognition in the context of genetically variable pathogens such as HIV-1. In this study, we used a combinatorial library containing 24 billion octamer peptides to characterize the cross-reactivity profiles of CD8⁺ T cells specific for the immunodominant HIV-1 subtype B Nef epitope VY8 (VPLRPMTY) presented by HLA-B^*35∶01. In conjunction, we examined naturally occurring antigenic variations within the VY8 epitope. Sequence analysis of plasma viral RNA isolated from 336 HIV-1-infected individuals revealed variability at position (P) 3 and P8 of VY8; Phe at P8, but not Val at P3, was identified as an HLA-B^*35∶01-associated polymorphism. VY8-specific T cells generated from several different HIV-1-infected patients showed unique and clonotype-dependent cross-reactivity footprints. Nonetheless, all T cells recognized both the index Leu and mutant Val at P3 equally well. In contrast, competitive titration assays revealed that the Tyr to Phe substitution at P8 reduced T cell recognition by 50–130 fold despite intact peptide binding to HLA-B^*35∶01. These findings explain the preferential selection of Phe at the C-terminus of VY8 in HLA-B^*35∶01⁺ individuals and demonstrate that HIV-1 can exploit the limitations of T cell recognition in vivo.     

In Vitro Priming Recapitulates In Vivo HIV-1 Specific T Cell Responses,Revealing Rapid Loss of Virus Reactive CD4+ T Cells in Acute HIV-1 Infection

Background

The requirements for priming of HIV-specific T cell responses initially seen in infected individuals remain to be defined. Activation of T cell responses in lymph nodes requires cell-cell contact between T cells and DCs, which can give concurrent activation of T cells and HIV transmission.

Methodology

The study aim was to establish whether DCs pulsed with HIV-1 could prime HIV-specific T cell responses and to characterize these responses. Both infectious and aldrithiol-2 inactivated noninfectious HIV-1 were compared to establish efficiencies in priming and the type of responses elicited.

Findings

Our findings show that both infectious and inactivated HIV-1 pulsed DCs can prime HIV-specific responses from naïve T cells. Responses included several CD4⁺ and CD8⁺ T cell epitopes shown to be recognized in vivo by acutely and chronically infected individuals and some CD4⁺ T cell epitopes not identified previously. Follow up studies of acute and recent HIV infected samples revealed that these latter epitopes are among the earliest recognized in vivo, but the responses are lost rapidly, presumably through activation-induced general CD4⁺ T cell depletion which renders the newly activated HIV-specific CD4⁺ T cells prime targets for elimination.

Conclusion

Our studies highlight the ability of DCs to efficiently prime naïve T cells and induce a broad repertoire of HIV-specific responses and also provide valuable insights to the pathogenesis of HIV-1 infection in vivo.     

A Phase I Randomized Therapeutic MVA-B Vaccination Improves the Magnitude and Quality of the T Cell Immune Responses in HIV-1-Infected Subjects on HAART

Trial Design

Previous studies suggested that poxvirus-based vaccines might be instrumental in the therapeutic HIV field. A phase I clinical trial was conducted in HIV-1-infected patients on highly active antiretroviral therapy (HAART), with CD4 T cell counts above 450 cells/mm³ and undetectable viremia. Thirty participants were randomized (2:1) to receive either 3 intramuscular injections of MVA-B vaccine (coding for clade B HIV-1 Env, Gag, Pol and Nef antigens) or placebo, followed by interruption of HAART.

Methods

The magnitude, breadth, quality and phenotype of the HIV-1-specific T cell response were assayed by intracellular cytokine staining (ICS) in 22 volunteers pre- and post-vaccination.

Results

MVA-B vaccine induced newly detected HIV-1-specific CD4 T cell responses and expanded pre-existing responses (mostly against Gag, Pol and Nef antigens) that were high in magnitude, broadly directed and showed an enhanced polyfunctionality with a T effector memory (TEM) phenotype, while maintaining the magnitude and quality of the pre-existing HIV-1-specific CD8 T cell responses. In addition, vaccination also triggered preferential CD8⁺ T cell polyfunctional responses to the MVA vector antigens that increase in magnitude after two and three booster doses.

Conclusion

MVA-B vaccination represents a feasible strategy to improve T cell responses in individuals with pre-existing HIV-1-specific immunity.

Trial Registration

ClinicalTrials.gov NCT01571466     

The HIV-1 Tat Protein Induces the Activation of CD8+ T Cells and Affects In Vivo the Magnitude and Kinetics of Antiviral Responses

T cells are functionally compromised during HIV infection despite their increased activation and proliferation. Although T cell hyperactivation is one of the best predictive markers for disease progression, its causes are poorly understood. Anti-tat natural immunity as well as anti-tat antibodies induced by Tat immunization protect from progression to AIDS and reverse signs of immune activation in HIV-infected patients suggesting a role of Tat in T cell dysfunctionality. The Tat protein of HIV-1 is known to induce, in vitro, the activation of CD4⁺ T lymphocytes, but its role on CD8⁺ T cells and how these effects modulate, in vivo, the immune response to pathogens are not known. To characterize the role of Tat in T cell hyperactivation and dysfunction, we examined the effect of Tat on CD8⁺ T cell responses and antiviral immunity in different ex vivo and in vivo models of antigenic stimulation, including HSV infection. We demonstrate for the first time that the presence of Tat during priming of CD8⁺ T cells favors the activation of antigen-specific CTLs. Effector CD8⁺ T cells generated in the presence of Tat undergo an enhanced and prolonged expansion that turns to a partial dysfunctionality at the peak of the response, and worsens HSV acute infection. Moreover, Tat favors the development of effector memory CD8⁺ T cells and a transient loss of B cells, two hallmarks of the chronic immune activation observed in HIV-infected patients. Our data provide evidence that Tat affects CD8⁺ T cell responses to co-pathogens and suggest that Tat may contribute to the CD8⁺ T cell hyperactivation observed in HIV-infected individuals.     

Full-Length HIV-1 Immunogens Induce Greater Magnitude and Comparable Breadth of T Lymphocyte Responses to Conserved HIV-1 Regions Compared with Conserved-Region-Only HIV-1 Immunogens in Rhesus Monkeys

A global HIV-1 vaccine will likely need to induce immune responses against conserved HIV-1 regions to contend with the profound genetic diversity of HIV-1. Here we evaluated the capacity of immunogens consisting of only highly conserved HIV-1 sequences that are aimed at focusing cellular immune responses on these potentially critical regions. We assessed in rhesus monkeys the breadth and magnitude of T lymphocyte responses elicited by adenovirus vectors expressing either full-length HIV-1 Gag/Pol/Env immunogens or concatenated immunogens consisting of only highly conserved HIV-1 sequences. Surprisingly, we found that the full-length immunogens induced comparable breadth (P = 1.0) and greater magnitude (P = 0.01) of CD8⁺ T lymphocyte responses against conserved HIV-1 regions compared with the conserved-region-only immunogens. Moreover, the full-length immunogens induced a 5-fold increased total breadth of HIV-1-specific T lymphocyte responses compared with the conserved-region-only immunogens (P = 0.007). These results suggest that full-length HIV-1 immunogens elicit a substantially increased magnitude and breadth of cellular immune responses compared with conserved-region-only HIV-1 immunogens, including greater magnitude and comparable breadth of responses against conserved sequences.     

Dendritic Cell Mediated Delivery of Plasmid DNA Encoding LAMP/HIV-1 Gag Fusion Immunogen Enhances T Cell Epitope Responses in HLA DR4 Transgenic Mice

This report describes the identification and bioinformatics analysis of HLA-DR4-restricted HIV-1 Gag epitope peptides, and the application of dendritic cell mediated immunization of DNA plasmid constructs. BALB/c (H-2d) and HLA-DR4 (DRA1*0101, DRB1*0401) transgenic mice were immunized with immature dendritic cells transfected by a recombinant DNA plasmid encoding the lysosome-associated membrane protein-1/HIV-1 Gag (pLAMP/gag) chimera antigen. Three immunization protocols were compared: 1) primary subcutaneous immunization with 1×10⁵ immature dendritic cells transfected by electroporation with the pLAMP/gag DNA plasmid, and a second subcutaneous immunization with the naked pLAMP/gag DNA plasmid; 2) primary immunization as above, and a second subcutaneous immunization with a pool of overlapping peptides spanning the HIV-1 Gag sequence; and 3) immunization twice by subcutaneous injection of the pLAMP/gag DNA plasmid. Primary immunization with pLAMP/gag-transfected dendritic cells elicited the greatest number of peptide specific T-cell responses, as measured by ex vivo IFN-γ ELISpot assay, both in BALB/c and HLA-DR4 transgenic mice. The pLAMP/gag-transfected dendritic cells prime and naked DNA boost immunization protocol also resulted in an increased apparent avidity of peptide in the ELISpot assay. Strikingly, 20 of 25 peptide-specific T-cell responses in the HLA-DR4 transgenic mice contained sequences that corresponded, entirely or partially to 18 of the 19 human HLA-DR4 epitopes listed in the HIV molecular immunology database. Selection of the most conserved epitope peptides as vaccine targets was facilitated by analysis of their representation and variability in all reported sequences. These data provide a model system that demonstrates a) the superiority of immunization with dendritic cells transfected with LAMP/gag plasmid DNA, as compared to naked DNA, b) the value of HLA transgenic mice as a model system for the identification and evaluation of epitope-based vaccine strategies, and c) the application of variability analysis across reported sequences in public databases for selection of historically conserved HIV epitopes as vaccine targets.     

Therapeutic Vaccination against the Rhesus Lymphocryptovirus EBNA-1 Homologue,rhEBNA-1, Elicits T Cell Responses to Novel Epitopes in Rhesus Macaques

Epstein-Barr virus (EBV) is a vaccine/immunotherapy target due to its association with several human malignancies. EBNA-1 is an EBV protein consistently expressed in all EBV-associated cancers. Herein, EBNA-1-specific T cell epitopes were evaluated after AdC–rhEBNA-1 immunizations in chronically lymphocryptovirus-infected rhesus macaques, an EBV infection model. Preexisting rhEBNA-1-specific responses were augmented in 4/12 animals, and new epitopes were recognized in 5/12 animals after vaccinations. This study demonstrated that EBNA-1-specific T cells can be expanded by vaccination.     

Elimination of HIV-1-Infected Primary T Cell Reservoirs in an In Vitro Model of Latency

Establishment of long-lived cellular reservoirs of HIV-1 represents a major therapeutic challenge to virus eradication. In this study, we utilized a human primary cell model of HIV-1 latency to evaluate the requirements for efficient virus reactivation from, and the selective elimination of, latently infected human T cells. Ectopic expression of BCL2 supported the replication and spread of R5-tropic HIV-1 in activated CD4⁺ T cells. After IL-2 withdrawal, the HIV-1-infected T cells survived as resting cells for several months. Unexpectedly, these resting T cells continue to produce detectable levels of infectious virus, albeit at a lower frequency than cells maintained in IL-2. In the presence of HIV-1 inhibitors, reactivation of the resting T cells with γc-cytokines and allogeneic dendritic cells completely extinguished HIV-1 infectivity. We also evaluated the ability of the bacterial LukED cytotoxin to target and kill CCR5-expressing cells. After γc-cytokine stimulation, LukED treatment eliminated both HIV-1-infected resting cells and the non-infected CCR5⁺ cells. Importantly, complete clearance of in vitro HIV-1 reservoirs by LukED required a lower threshold of cytokine signals relative to HIV-1 inhibitors. Thus, the primary T cell-based HIV-1 latency model could facilitate the development of novel agents and therapeutic strategies that could effectively eradicate HIV-1.     

Recombinant GM2-Activator Protein Stimulates In Vivo Degradation of GA2 in GM2 Gangliosidosis AB Variant Fibroblasts But Exhibits No Detectable Binding of GA2 in an In Vitro Assay

The interaction between glycosphingolipids and recombinant human GM2-activator was studied in a microwell binding assay. A-series gangliosides like GM3, GM2 and GM1 were strongly bound by the recombinant human GM2 activator. A weak binding was observed to GD1b and sulfatide, while neutral glycolipids were not bound. Optimal binding occurred at pH 4.2 and was inhibited by increasing concentrations of citrate buffer and NaCl. In contrast with these in vitro results the recombinant human GM2-activator is able to restore the degradation of GA2 in fibroblasts from patients with the AB variant of GM2 gangliosidosis in vivo.     

Exposure of a Distinct PDCA-1+ (CD317) B Cell Population to Agonistic Anti-4-1BB (CD137) Inhibits T and B Cell Responses Both In Vitro and In Vivo

4-1BB (CD137) is an important T cell activating molecule. Here we report that it also promotes development of a distinct B cell subpopulation co-expressing PDCA-1. 4-1BB is expressed constitutively, and its expression is increased when PDCA-1⁺ B cells are activated. We found that despite a high level of surface expression of 4-1BB on PDCA-1⁺ B cells, treatment of these cells with agonistic anti-4-1BB mAb stimulated the expression of only a few activation markers (B7-2, MHC II, PD-L2), cytokines (IL-12p40/p70), and chemokines (MCP-1, RANTES), as well as sTNFR1, and the immunosuppressive enzyme, IDO. Although the PDCA-1⁺ B cells stimulated by anti-4-1BB expressed MHC II at high levels and took up antigens efficiently, Ig class switching was inhibited when they were pulsed with T-independent (TI) or T-dependent (TD) Ags and adoptively transferred into syngeneic recipients. Furthermore, when anti-4-1BB-treated PDCA-1⁺ B cells were pulsed with OVA peptide and combined with Vα2⁺CD4⁺ T cells, Ag-specific cell division was inhibited both in vitro and in vivo. Our findings suggest that the 4-1BB signal transforms PDCA-1⁺ B cells into propagators of negative immune regulation, and establish an important role for 4-1BB in PDCA-1⁺ B cell development and function.     

Adaptation of CD8 T Cell Responses to Changing HIV-1 Sequences in a Cohort of HIV-1 Infected Individuals Not Selected for a Certain HLA Allele

HIV evades CD8 T cell mediated pressure by viral escape mutations in targeted CD8 T cell epitopes. A viral escape mutation can lead to a decline of the respective CD8 T cell response. Our question was what happened after the decline of a CD8 T cell response and - in the case of viral escape – if a new CD8 T cell response towards the mutated antigen could be generated in a population not selected for certain HLA alleles. We studied 19 antiretroviral-naïve HIV-1 infected individuals with different disease courses longitudinally. A median number of 12 (range 2-24) CD8 T cell responses towards Gag and Nef were detected per study subject. A total of 30 declining CD8 T cell responses were studied in detail and viral sequence analyses showed amino acid changes in 25 (83%) of these. Peptide titration assays and definition of optimal CD8 T cell epitopes revealed 12 viral escape mutations with one de-novo response (8%). The de-novo response, however, showed less effector functions than the original CD8 T cell response. In addition we identified 4 shifts in immunodominance. For one further shift in immunodominance, the mutations occurred outside the optimal epitope and might represent processing changes. Interestingly, four adaptations to the virus (the de-novo response and 3 shifts in immunodominance) occurred in the group of chronically infected progressors. None of the subjects with adaptation to the changing virus carried the HLA alleles B57, B*58:01 or B27. Our results show that CD8 T cell responses adapt to the mutations of HIV. However it was limited to only 20% (5 out of 25) of the epitopes with viral sequence changes in a cohort not expressing protective HLA alleles.     

Evaluation of In Vitro Cross-Reactivity to Avian H5N1 and Pandemic H1N1 2009 Influenza Following Prime Boost Regimens of Seasonal Influenza Vaccination in Healthy Human Subjects: A Randomised Trial

Introduction

Recent studies have demonstrated that inactivated seasonal influenza vaccines (IIV) may elicit production of heterosubtypic antibodies, which can neutralize avian H5N1 virus in a small proportion of subjects. We hypothesized that prime boost regimens of live and inactivated trivalent seasonal influenza vaccines (LAIV and IIV) would enhance production of heterosubtypic immunity and provide evidence of cross-protection against other influenza viruses.

Methods

In an open-label study, 26 adult volunteers were randomized to receive one of four vaccine regimens containing two doses of 2009-10 seasonal influenza vaccines administered 8 (±1) weeks apart: 2 doses of LAIV; 2 doses of IIV; LAIV then IIV; IIV then LAIV. Humoral immunity assays for avian H5N1, 2009 pandemic H1N1 (pH1N1), and seasonal vaccine strains were performed on blood collected pre-vaccine and 2 and 4 weeks later. The percentage of cytokine-producing T-cells was compared with baseline 14 days after each dose.

Results

Subjects receiving IIV had prompt serological responses to vaccine strains. Two subjects receiving heterologous prime boost regimens had enhanced haemagglutination inhibition (HI) and neutralization (NT) titres against pH1N1, and one subject against avian H5N1; all three had pre-existing cross-reactive antibodies detected at baseline. Significantly elevated titres to H5N1 and pH1N1 by neuraminidase inhibition (NI) assay were observed following LAIV-IIV administration. Both vaccines elicited cross-reactive CD4+ T-cell responses to nucleoprotein of avian H5N1 and pH1N1. All regimens were safe and well tolerated.

Conclusion

Neither homologous nor heterologous prime boost immunization enhanced serum HI and NT titres to 2009 pH1N1 or avian H5N1 compared to single dose vaccine. However heterologous prime-boost vaccination did lead to in vitro evidence of cross-reactivity by NI; the significance of this finding is unclear. These data support the strategy of administering single dose trivalent seasonal influenza vaccine at the outset of an influenza pandemic while a specific vaccine is being developed.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01044095","term_id":"NCT01044095"}}NCT01044095     

A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent

Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a process that results in the exocytosis of allergic mediators. Modulation of mast cell degranulation by drugs and toxicants may have positive or adverse effects on human health. Mast cell function has been dissected in detail with the use of rat basophilic leukemia mast cells (RBL-2H3), a widely accepted model of human mucosal mast cells^3-5. Mast cell granule component and the allergic mediator β-hexosaminidase, which is released linearly in tandem with histamine from mast cells⁶, can easily and reliably be measured through reaction with a fluorogenic substrate, yielding measurable fluorescence intensity in a microplate assay that is amenable to high-throughput studies¹. Originally published by Naal et al.¹, we have adapted this degranulation assay for the screening of drugs and toxicants and demonstrate its use here.Triclosan is a broad-spectrum antibacterial agent that is present in many consumer products and has been found to be a therapeutic aid in human allergic skin disease^7-11, although the mechanism for this effect is unknown. Here we demonstrate an assay for the effect of triclosan on mast cell degranulation. We recently showed that triclosan strongly affects mast cell function². In an effort to avoid use of an organic solvent, triclosan is dissolved directly into aqueous buffer with heat and stirring, and resultant concentration is confirmed using UV-Vis spectrophotometry (using ε₂₈₀ = 4,200 L/M/cm)¹². This protocol has the potential to be used with a variety of chemicals to determine their effects on mast cell degranulation, and more broadly, their allergic potential.     

Association of Neisseria gonorrhoeae OpaCEA with Dendritic Cells Suppresses Their Ability to Elicit an HIV-1-Specific T Cell Memory Response

Infection with Neisseria gonorrhoeae (N. gonorrhoeae) can trigger an intense local inflammatory response at the site of infection, yet there is little specific immune response or development of immune memory. Gonococcal surface epitopes are known to undergo antigenic variation; however, this is unlikely to explain the weak immune response to infection since individuals can be re-infected by the same serotype. Previous studies have demonstrated that the colony opacity-associated (Opa) proteins on the N. gonorrhoeae surface can bind human carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) on CD4⁺ T cells to suppress T cell activation and proliferation. Interesting in this regard, N. gonorrhoeae infection is associated with impaired HIV-1 (human immunodeficiency virus type 1)-specific cytotoxic T-lymphocyte (CTL) responses and with transient increases in plasma viremia in HIV-1-infected patients, suggesting that N. gonorrhoeae may also subvert immune responses to co-pathogens. Since dendritic cells (DCs) are professional antigen presenting cells (APCs) that play a key role in the induction of an adaptive immune response, we investigated the effects of N. gonorrhoeae Opa proteins on human DC activation and function. While morphological changes reminiscent of DC maturation were evident upon N. gonorrhoeae infection, we observed a marked downregulation of DC maturation marker CD83 when the gonococci expressing CEACAM1-specific Opa_CEA, but not other Opa variants. Consistent with a gonococcal-induced defect in maturation, Opa_CEA binding to CEACAM1 reduced the DCs’ capacity to stimulate an allogeneic T cell proliferative response. Moreover, Opa_CEA-expressing N. gonorrhoeae showed the potential to impair DC-dependent development of specific adaptive immunity, since infection with Opa_CEA-positive gonococci suppressed the ability of DCs to stimulate HIV-1-specific memory CTL responses. These results reveal a novel mechanism to explain why infection of N. gonorrhoeae fails to trigger an effective specific immune response or develop immune memory, and may affect the potent synergy between gonorrhea and HIV-1 infection.     

A Combinatorial Peptide Library Around Variation of the Human Immunode ficiency Virus (HIV-1) V3 Domain Leads to Distinct T Helper Cell Responses

The hypervariable domain of the HIV gp120, the V3 loop domain, represents a target for neutralizing antibodies and for HIV vaccine strategies. In this study, we have investigated in murine species the potential cross-reactivity of immune responses elicited by immunization either with individual V3 peptides, derived from distinct HIV sequences (BRU, RF, SF2, MN and ELI sequences), or with a V3 combinatorial peptide library. We observed that individual V3 peptides are immunogenic but elicit a specific B- and T-cell immune response that is mainly restricted to the sequence of the immunizing peptide. In particular, T-cell responses that depend on T-cell receptor recognition of peptides bound to the molecules encoded by the major histocompatibility complex were significantly influenced by small differences in the peptide amino acid sequence. The combinatorial V3 peptide library, previously described as B- and T-cell immunogens, induced a more broadly reactive immune response, specially when T-cell cytokine secretion was used as a readout for restimulation of T-cells with individual V3 peptides. These data suggest that amino acid variations in the sequence of an antigenic peptide could lead to the induction of different transducing signals in the primed T-cell population and to the activation of T-cells with distinct cytokine secretion properties. These observations may have implications in the understanding of antigenic variability and in the design of vaccine strategies.     

Safety,Humoral and Cell Mediated Immune Responses to Two Formulations of an Inactivated,Split-Virion Influenza A/H5N1 Vaccine in Children

Background

Highly pathogenic influenza A/H5N1 has caused outbreaks in wild birds and poultry in Asia, Africa and Europe. It has also infected people, especially children, causing severe illness and death. Although the virus shows limited ability to transmit between humans, A/H5N1 represents a potential source of the next influenza pandemic. This study assesses the safety and immunogenicity of aluminium hydroxide adjuvanted (Al) and non adjuvanted influenza A/Vietnam/1194/2004 NIBRG-14 (H5N1) vaccine in children.

Methods and Findings

In a Phase II, open, randomised, multicentre trial 180 children aged 6 months to 17 years received two injections, 21 days apart, of vaccine containing either: 30 µg haemagglutinin (HA) with adjuvant (30 µg+Al) or 7.5 µg HA without adjuvant. An additional 60 children aged 6–35 months received two “half dose” injections (ie 15 µg+Al or 3.8 µg). Safety was followed for 21 days after vaccination. Antibody responses were assessed 21 days after each injection and cellular immune responses were explored. Vaccination appeared well tolerated in all age groups. The 30 µg+Al formulation was more immunogenic than 7.5 µg in all age groups: in these two groups 79% and 46% had haemagglutinination inhibition antibody titres ≥32 (1/dil). Among 6–35 month-olds, the full doses were more immunogenic than their half dose equivalents. Vaccination induced a predominantly Th2 response against H5 HA.

Conclusions

This influenza A(H5N1) vaccine was well tolerated and immunogenic in children and infants, with Al adjuvant providing a clear immunogenic advantage. These results demonstrate that an H5N1 Al-adjuvanted vaccine, previously shown to be immunogenic and safe in adults, can also be used in children, the group most at risk for pandemic influenza.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00491985","term_id":"NCT00491985"}}NCT00491985     

Polyfunctional Type-1, -2, and -17 CD8+ T Cell Responses to Apoptotic Self-Antigens Correlate with the Chronic Evolution of Hepatitis C Virus Infection

Caspase-dependent cleavage of antigens associated with apoptotic cells plays a prominent role in the generation of CD8⁺ T cell responses in various infectious diseases. We found that the emergence of a large population of autoreactive CD8⁺ T effector cells specific for apoptotic T cell-associated self-epitopes exceeds the antiviral responses in patients with acute hepatitis C virus infection. Importantly, they endow mixed polyfunctional type-1, type-2 and type-17 responses and correlate with the chronic progression of infection. This evolution is related to the selection of autoreactive CD8⁺ T cells with higher T cell receptor avidity, whereas those with lower avidity undergo prompt contraction in patients who clear infection. These findings demonstrate a previously undescribed strict link between the emergence of high frequencies of mixed autoreactive CD8⁺ T cells producing a broad array of cytokines (IFN-γ, IL-17, IL-4, IL-2…) and the progression toward chronic disease in a human model of acute infection.