Aug 2026· Proceedings of the National Academy of Sciences of the United States of America· Vol 123 32, pp.
e2527880123
· 0 citations· 40 references
Medicine
Abstract
Bispecific antibodies that reroute cytotoxic effectors toward infected cells are promising HIV-1 cure agents, yet existing formats bind Env and are limited by antigenic variation and Env down-regulation. We engineered a TCR-mimic single-chain diabody, HI12, that recognizes a conserved Pol-derived peptide presented by HLA-A*02:01 and evaluated its effect in HLA-matched, HIV-infected humanized mice. When administered during early antiretroviral therapy (ART), HI12 was well tolerated, activated CD8+ T cells, and accelerated plasma virus decay. Treatment produced three- to eightfold reductions in intact and total proviral DNA within lymph-node and splenic CD4+ T cells, indicating substantive reservoir clearance. After ART interruption, HI12-treated animals showed a significant delay in viral rebound compared with controls, linking reservoir reduction to improved posttherapy control. These findings provide in vivo evidence that a peptide-HLA-directed bispecific antibody can both shrink the intact HIV reservoir and defer viral recrudescence, supporting further development of TCR-mimic bispecific antibodies for cure strategies.
Despite ART, HIV-1 persists in latency and rapidly rebounds after interruption. A functional cure will require potent CD8+ T cells that recognize and eliminate latent reservoirs. mRNA vaccines enable rapid, flexible, multi-epitope design. We tested an mRNA encoding tandem CD8+ epitopes with flanking sequences optimized for antigen processing/MHC-I presentation in mice and human PBMCs and assessed co-stimulation by a TLR8 ligand (TLR8L).
We generated mRNAs carrying model epitopes either directly concatenated or appended with flanking regions designed to favor proteasomal generation. HLA-A*02:01 transgenic mice were immunized, and antigen-specific CD8+ T-cell responses and multifunctionality were quantified by ELISpot and flow cytometry. We then established a 10-day in vitro boosting assay using PBMCs from people with HIV-1 cultured with FLT3L and exposed to mRNA encoding tandem HIV-1 epitopes. Epitope-specific CD8+ T-cell frequencies were measured by HLA-tetramers, and cytotoxic potential was assessed by granzyme B and perforin expression.
In HLA-A*02:01 mice, the flanking-optimized tandem design increased multifunctional CD8+ responses co-producing CD107a/IFN-γ/TNF. In PBMCs from people with HIV-1, the HIV epitope—tandem mRNA increased epitope-specific CD8+ T-cell frequency 3.4-fold versus no vaccine (p = 0.0137); addition of TLR8L further raised this to 4.7-fold (p = 0.0273). The proportion of cells co-expressing granzyme B and perforin rose from 40.8% to 80.5% with TLR8L (p = 0.0137).
An mRNA vaccine encoding tandem CD8+ T-cell epitopes with optimized flanking sequences elicited quantitatively and qualitatively superior epitope-specific CD8+ responses in HLA-A*02:01 mice and in PBMCs from people with HIV-1. TLR8L further enhanced these responses. This platform supports development of therapeutic mRNA vaccines aimed at strengthening CD8+ T-cell immunity toward a functional cure of HIV-1.
Japan Society for the Promotion of Science Grant-in-Aid for Early-Career Scientists
Vaccines and Immunotherapy (VAC)
T. Nogimori, H. Nguyen, M. Kumamoto et al.· Journal of Immunology· 0 citations
ABSTRACT The persistence of latent HIV-1 reservoirs remains the primary barrier to a cure. Shock and kill strategies aim to reactivate these reservoirs and eliminate them via effector cells, such as natural killer (NK) cells. However, chronic infection leaves NK cells exhausted. In this study, we investigated the interplay between cytokine-mediated NK cell activation and antibody-dependent cellular cytotoxicity (ADCC) across diverse HIV-1 subtypes. We demonstrated that while cytokine stimulation enhanced natural cytotoxicity, it simultaneously induces shedding of the Fc receptor CD16 via the metalloproteinase enzyme ADAM17. However, restoring CD16 expression through ADAM17 inhibition (TAPI-1) did not improve ADCC, suggesting that CD16 surface levels in NK cells are not the only limiting factor. On the other hand, Fc-engineered broadly neutralizing antibodies (bNAbs) with increased CD16 affinity, in particular LPLIL and GASDALIE, significantly enhance ADCC across different HIV-1 subtypes, regardless of NK cell activation or CD16 downregulation. These findings suggest that enhancing receptor affinity of bNAbs can bypass viral immune evasion and NK cell exhaustion, supporting their potential incorporation into HIV cure strategies. IMPORTANCE Eradicating latent HIV reservoirs remains a global health priority as it would liberate millions of people living with HIV (PLWH) from the economic and physiological burdens of lifelong antiretroviral therapy (ART). By utilizing a primary human cell model that resembles in vivo conditions across diverse viral strains, we identified that simply preventing CD16 receptor shedding from natural killer (NK) cells is insufficient to improve HIV-1 clearance. Instead, we demonstrated that enhancing the binding of antibodies to the CD16 receptor enables NK cells to overcome viral immune evasion and the loss of CD16 expression. This allows for potent elimination of infected cells through antibody-dependent cellular cytotoxicity (ADCC). These findings provide a clear strategy for designing more effective “kill” components in future therapeutic strategies. Eradicating latent HIV reservoirs remains a global health priority as it would liberate millions of people living with HIV (PLWH) from the economic and physiological burdens of lifelong antiretroviral therapy (ART). By utilizing a primary human cell model that resembles in vivo conditions across diverse viral strains, we identified that simply preventing CD16 receptor shedding from natural killer (NK) cells is insufficient to improve HIV-1 clearance. Instead, we demonstrated that enhancing the binding of antibodies to the CD16 receptor enables NK cells to overcome viral immune evasion and the loss of CD16 expression. This allows for potent elimination of infected cells through antibody-dependent cellular cytotoxicity (ADCC). These findings provide a clear strategy for designing more effective “kill” components in future therapeutic strategies.
Claudia Melo, Teresa Murphy, C. Holmberg et al.· mBio· 0 citations
The development of an effective anti-HIV vaccine remains a critical tool to halt the HIV epidemic, particularly due to the limits of the PrEP strategies. CD4+ T lymphocytes play a crucial role in vaccine efficacy; however, they are also the primary target cells for HIV infection. Given these opposing roles, we hypothesized that an in-depth characterization of CD4+ T cell responses to vaccination will elucidate mechanisms of protection.
To test this hypothesis, we immunized rhesus macaques using a prime-boost strategy that included a DV1-DNA prime and boosts with ALVAC alone or in combination with DV1-gp120 protein, followed by intravaginal exposures to SIVmac251. We then integrated data obtained by flow cytometry and plasma proteome analyses, as well as transcriptome and chromatin accessibility analyses of CD3+ cells, to investigate how the vaccine shapes the CD4+ T cell immunity and how these responses cooperate in reducing the acquisition.
We found that DV1 DNA/ALVAC/gp120 vaccine elicited envelope-specific immunomodulatory Tr1 CD4+ T cells, and that total Tr1 responses were associated with a reduced risk of viral acquisition. Transcriptome analyses of CD3+ cells identified vaccine-induced Tr1, as well as IL-27, gene signatures that were associated with a reduced risk, confirming the protective role of these cells. Furthermore, the study of the epigenetic landscape of CD3+ cells revealed that the epigenetic reprogramming of enhancer region upstream of the transcription factors BATF and IRF-1, which are involved in the development of Tr1 cells, correlated with lower viral acquisition.
These data suggest that immunoinhibitory Tr1 cells contribute to vaccine efficacy by decreasing inflammation and potentially counteracting the development and recruitment of HIV target cells.
n/a
Vaccines and Immunotherapy (VAC)
Massimiliano Bissa, S. Fourati, Sohyoung Kim et al.· Journal of Immunology· 0 citations
Antibodies against the V1V2 domain of the HIV envelope glycoprotein have been identified as a potential correlate of reduced infection risk in three large HIV vaccine efficacy trials. Although vaccine-elicited anti-V1V2 antibodies do not mediate potent virus-neutralizing activities, they mediate Fc-dependent effector functions. Strategies that enhance the magnitude and quality of these responses may improve HIV vaccine efficacy.
We examined a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) vaccine encoding the V1V2 domain of CRF_01.AE244 on the 2J9C scaffold. Immunogenicity was assessed in three animal models: mice, rabbits, and rhesus macaques, following two or more immunizations. Antibody binding, cross-reactivity, and Fc-mediated functions were quantified using Luminex antigen-binding assays, virion- and cell-surface Env recognition assays, antibody-dependent cellular phagocytosis (ADCP), and Fc receptor binding.
In mice two doses of the V1V2 mRNA-LNP vaccine elicited robust, cross-reactive serum IgG responses that recognized soluble Env and native Env on cells and virions. Importantly, murine IgG2a antibodies were generated that displayed Fc-mediated activities. However, in rabbits the elicited responses were directed mainly against the scaffold, with minimal V1V2-specific antibodies even after four vaccinations. In contrast, rhesus macaques developed high-level V1V2-specific antibodies responses after two vaccinations, comparable to those observed in mice.
The V1V2 mRNA-LNP vaccine is highly immunogenic in mice and rhesus macaques, eliciting cross-clade functional antibodies capable of recognizing native Env. The marked species-dependent differences, most notably the weak V1V2 targeting in rabbits, underscore the importance of selecting appropriate animal models for preclinical HIV vaccine evaluation and may provide insights relevant to vaccine testing against other pathogens.
VA Merit Review I01BX005616, NIH R01 AI148327
Vaccines and Immunotherapy (VAC)
Catarina E. Hioe, Xiaomei Liu, C. Yengo et al.· Journal of Immunology· 0 citations
Personalized neoantigen (neoAg) vaccines have shown clinical promise in solid tumors1–8, yet their efficacy and mechanism of action in hematopoietic malignancies remain poorly defined9–11. Herein, we establish an immunocompetent syngeneic A20 B-cell lymphoma platform to test the efficacy of neoAg vaccines used either as mono- or combinatorial therapies with other immunotherapies12–17. Whereas subcutaneous A20 tumors were refractory to single-agent αPD-1 or αCTLA4 therapy, they were eradicated in a T cell-dependent manner in 90% of syngeneic hosts treated with dual immune checkpoint therapy (dual ICT, i.e., αPD-1 + αCTLA4). By mapping antigen specificity of dual-ICT-elicited T cells, we identified and validated dominant endogenous A20 MHC-I and MHC-II neoantigens and designed therapeutic synthetic long peptide (SLP) vaccines containing these neoepitopes. This vaccine (A20 neoVAX) promoted robust neoAg-specific CD4□ and CD8□ T cell responses in naïve syngeneic BALB/c mice and induced tumor rejection in ∼70% of subcutaneous tumor-bearing mice. In addition, nearly all mice rejected their subcutaneous A20 tumors when A20 neoVAX was combined with αPD-1. To render the results of this study more physiologic, we developed a systemic A20 lymphoma model and found that dual ICT failed to control tumor progression and A20 neoVAX delayed tumor progression and prolonged animal survival but did not induce tumor rejection. In contrast, A20 neoVAX plus dual ICT achieved durable systemic tumor elimination. Mechanistically, the combination of A20 neoVAX plus dual ICT amplified priming of A20 neoAg-specific T cells, prevented T cell dysfunction, sustained the cytotoxic capacity of tumor-specific CD8+ T cells, and induced Th1-skewing of CD4+ T cells in tumor and peripheral compartments. To increase the clinical relevance of these findings and to minimize potential adverse events in tumor-bearing, therapeutically treated individuals, we substituted CD8-targeted cytokine muteins (CD8-IL2 or CD8-IL21) for αCTLA4. These agents represent genetically modified forms of IL-2 or IL-21 that selectively stimulate CD8+ T cells but have significantly reduced capacity to activate chronic inflammation and immunosuppressive functions of other immune cells. Whereas mice bearing systemic A20 lymphoma treated with either nothing, A20 neoVAX, or A20 neoVAX + CD8-IL2 failed to control tumor outgrowth, 66.7% of tumor-bearing mice treated with A20 neoVAX + CD8-IL2 + αPD-1 rejected their tumors. In similar experiments in which CD8-IL21 was substituted for CD8-IL2, tumor clearance was also observed in two-thirds of A20-bearing mice but now rejection occurred in the absence of αPD1. Together, these data define a framework for optimal personalized neoAg vaccination in B-lymphoma and demonstrate that neoAg vaccines can safely synergize with CD8+ T cell-selective immunotherapies to prevent T-cell dysfunction and generate durable systemic anti-tumor immunity.
Yuang Song, E. Aladyeva, Ruan F. Vieira Medrano et al.· bioRxiv· 0 citations
Targeted immunotherapies aimed at enhancing antiviral T cell responses are of particular interest for treating neurotropic viral infections such as West Nile Virus (WNV), which lacks a licensed human vaccine. Previous studies have shown that DEC-205+ dendritic cells (DCs) in the central nervous system (CNS) play a role in reactivating antiviral immunity during WNV infection.
Methods to investigate this: a hybrid scFv antibody targeting DEC-205 and conjugated to a peptide from the WNV NS4b protein was administered to mice infected with WNV-TX. Poly I:C was co-delivered as an adjuvant to promote DC maturation. Immunological outcomes were assessed by quantifying co-stimulatory molecule expression (CD40, CD80, CD86) on DCs and evaluating T cell activation markers and cytokine profiles.
Mice receiving the DEC-205—NS4b scFv showed increased expression of activation markers and higher levels of pro-inflammatory cytokines, suggesting enhanced antiviral immunity.
These findings support targeted DC-based strategies as a promising approach for future WNV vaccine development.
Cal Poly Pomona Project Hatchery
Immune Response Regulation: Cellular Mechanisms (IRC)
Manuel Ramírez, Joshua Herzler, Michaela Montinola et al.· Journal of Immunology· 0 citations
