Factors Associated with the Development of Cross-Reactive Neutralizing Antibodies during Human Immunodeficiency Virus Type 1 Infection

Although the use of chimeric antigen receptors (CARs) based on single-chain antibodies for gene immunotherapy of cancers is increasing due to promising recent results, the earliest CAR therapeutic trials were done for HIV-1 infection in the late 1990s. This approach utilized a CAR based on human CD4 as a binding domain and was abandoned for a lack of efficacy. The growing number of HIV-1 broadly neutralizing antibodies (BNAbs) offers the opportunity to generate novel CARs that may be more active and revisit this modality for HIV-1 immunotherapy. We used sequences from seven well-defined BNAbs varying in binding sites and generated single-chain-antibody-based CARs. These CARs included 10E8, 3BNC117, PG9, PGT126, PGT128, VRC01, and X5. Each novel CAR exhibited conformationally relevant expression on the surface of transduced cells, mediated specific proliferation and killing in response to HIV-1-infected cells, and conferred potent antiviral activity (reduction of viral replication in log 10 units) to transduced CD8 ؉ T lymphocytes. The antiviral activity of these CARs was reproducible but varied according to the strain of virus. These findings indicated that BNAbs are excellent candidates for developing novel CARs to consider for the immunotherapeutic treatment of HIV-1. R ecent years have seen a surge in immunotherapeutic approaches for treating malignancy, including numerous promising human trials of chimeric antigen receptor (CAR) gene therapy to generate tumor-specific T cells, based on the importance of CD8 ϩ T lymphocytes (CTLs) in tumor surveillance and malignant cell clearance through cytotoxicity. The general approach has been to identify monoclonal antibodies that bind a tumor cell surface antigen and use a single-chain version of the antibody as an artificial T cell receptor by genetic fusion to the CD3 chain signaling domain. As opposed to native T cell receptors (TCRs), CARs have the advantage of being major histocompatibility complex (MHC) unrestricted and therefore broadly applicable across human individuals and are also unaffected by tumor cell immune evasion through MHC downregulation. IMPORTANCE While chimeric antigen receptors (CARsNotably, one of the earliest tested clinical applications of CARs was for the treatment of HIV-1 infection. In 1994, Roberts et al. designed two virus-specific CARs using CD4 or a single-chain antibody as the binding domain for recombinant gp120 on the surface of cells (1), and these CARs were shown subsequently to have the direct capacity to kill HIV-1-infected cells and suppress viral replication at levels similar to those of HIV-1-specific CTL clones isolated from infected persons (2). Based on these data, the CD4-based CAR, consisting of the CD4 extracellular and transmembrane domains fused to the CD3 intracellular signaling domain (CD4 Ϫ ), was advanced to clinical trials starting in the late 1990s, using retroviral transduction of autologous peripheral blood T lymphocytes and reinfusion. Unfortunately, this effort was abandoned after these trials showed...

Section: Discussionmentioning

confidence: 99%

HIV-1-Specific Chimeric Antigen Receptors Based on Broadly Neutralizing Antibodies

Ali

Kitchen

Chen

et al. 2016

“…In the current study, we built upon these recent findings and used longitudinally cloned quasispecies gp160 env genes isolated from plasma from two subjects (VC10014 and VC20013). These two subtype B-infected subjects gradually developed moderate bNAbs (33) within a few years of infection by targeting two distinct regions of Env, an epitope overlapping the CD4 binding site in VC10014 and the membrane-proximal external region (MPER) in VC20013 as noted in the accompanying article by Sather et al (51). We assessed the phylogenetic and neutralization profiles and epitope exposure of the Envs based on binding to neutralizing monoclonal antibodies (NMAbs) and used these data to select a subset of variants to design vaccine strategies in rabbits.…”

mentioning

confidence: 99%

“…Prolonged antigenic exposure is a key clinical parameter associated with the natural development of bNAbs in elite neutralizers (24,(31)(32)(33), suggesting that the dynamic interactions occurring between viral quasispecies and host B cells result in continuously changing antibody specificities in vivo (24,25) and likely contribute to the generation of bNAbs (34). In fact, multiple pathways to neutralization breadth have been shown in different subjects (9,33,(35)(36)(37)(38), whereas in some subjects, antibodies with a single specificity or a few specificities can account for much of the neutralization activity (10,29,33,(39)(40)(41)(42). Thus, further understanding of the humoral response in infected individuals who naturally develop bNAbs could guide the selection of candidate Env immunogens and the design of vaccine strategies that elicit breadth (43).…”

mentioning

confidence: 99%

Envelope Variants Circulating as Initial Neutralization Breadth Developed in Two HIV-Infected Subjects Stimulate Multiclade Neutralizing Antibodies in Rabbits

Malherbe

Pissani

Sather

et al. 2014

Self Cite

Identifying characteristics of the human immunodeficiency virus type 1 (HIV-1) envelope that are effective in generating broad, protective antibodies remains a hurdle to HIV vaccine design. Emerging evidence of the development of broad and potent neutralizing antibodies in HIV-infected subjects suggests that founder and subsequent progeny viruses may express unique antigenic motifs that contribute to this developmental pathway. We hypothesize that over the course of natural infection, B cells are programmed to develop broad antibodies by exposure to select populations of emerging envelope quasispecies variants. To test this hypothesis, we identified two unrelated subjects whose antibodies demonstrated increasing neutralization breadth against a panel of HIV-1 isolates over time. Full-length functional env genes were cloned longitudinally from these subjects from months after infection through 2.6 to 5.8 years of infection. Motifs associated with the development of breadth in published, cross-sectional studies were found in both subjects. We compared the immunogenicity of envelope vaccines derived from time points obtained during and after broadening of neutralization activity within these subjects. Rabbits were coimmunized four times with selected multiple gp160 DNAs and gp140-trimeric envelope proteins. The affinity of the polyclonal response increased as a function of boosting. The most rapid and persistent neutralization of multiclade tier 1 viruses was elicited by envelopes that were circulating in plasma at time points prior to the development of 50% neutralization breadth in both human subjects. The breadth elicited in rabbits was not improved by exposure to later envelope variants. These data have implications for vaccine development in describing a target time point to identify optimal envelope immunogens. IMPORTANCEVaccine protection against viral infections correlates with the presence of neutralizing antibodies; thus, vaccine components capable of generating potent neutralization are likely to be critical constituents in an effective HIV vaccine. However, vaccines tested thus far have elicited only weak antibody responses and very modest, waning protection. We hypothesized that B cells develop broad antibodies by exposure to the evolving viral envelope population and tested this concept using multiple envelopes from two subjects who developed neutralization breadth within a few years of infection. We compared different combinations of envelopes from each subject to identify the most effective immunogens and regimens. In each subject, use of HIV envelopes circulating during the early development and maturation of breadth generated more-potent antibodies that were modestly cross neutralizing. These data suggest a new approach to identifying envelope immunogens that may be more effective in generating protective antibodies in humans.A human immunodeficiency virus type 1 (HIV-1) envelope (Env) component that effectively stimulates the humoral arm of the adaptive immune response will be a critical ...

“…Attempts to induce such bNAbs through vaccination have mostly been ineffective. Interestingly, in natural infection, serologic breadth develops only under conditions that seem counterintuitive to efficient B cell maturation processes, such as years of chronic immune activation, loss of CD4 T cells, high levels of exhaustion marker expression, and other phenotypic lymphocyte abnormalities (2)(3)(4)(5). In addition, high viral loads and coevolution of viral quasispecies have been implicated in the development of serologic breadth, suggesting that constant immune activation and antigen recognition may play a key role in HIV antibody maturation processes.…”

mentioning

confidence: 99%

Preservation of Peripheral T Follicular Helper Cell Function in HIV Controllers

Buranapraditkun

Pissani

Teigler

et al. 2017

The maturation process of high-affinity antibodies is a result of intricate interactions between B cells and follicular helper T (Tfh) cells occurring in lymphoid germinal centers. HIV infection induces significant chronic immune activation, phenotypic skewing, and inflammation driven by years of continuous viral replication. High levels of viremia as well as immune activation and dysfunction have been demonstrated to have a perturbing impact on the B cell memory compartment and contribute to B cell exhaustion. Counterintuitively, the factors associated with perturbation of the B cell compartment seem to be favorable for the generation of highly affinity-matured Env-specific antibodies in a minority of HIV-infected individuals. Thus, the impact of HIV antigenemia on B cells and Tfh cell interactions warrants further exploration. We therefore studied immunophenotypes of HIV-specific B cells in individuals with differing levels of viral control using HIV Env gp120 probes and characterized the functionality of matched T cells in peripheral blood. While CXCR5 ϩ CD4 ϩ T cells were significantly diminished in HIV progressors, we found that a small subset of gp120-specific interleukin-21 (IL-21)-secreting CXCR5 ϩ CD4 ϩ T cells were significantly associated with gp120-specific B cell frequencies. In contrast, neither bulk CXCR5 ϩ CD4 ϩ T cells nor other HIV antigen specificities were associated with gp120-specific B cell levels. HIV-specific B cells derived from elite controllers displayed greater amounts of gp120-specific B cells in the resting memory subset, whereas HIV-specific B cells in progressors accumulated in tissue-like and activated memory subsets. Furthermore, CXCR5 ϩ CD4 ϩ T cells from elite controllers showed a stronger ex vivo capacity to induce B cell maturation and immunoglobulin class switching than cells from HIV progressors.IMPORTANCE Dissecting the factors that are involved in B cell maturation and antibody development is important for HIV vaccine design. In this study, we found that HIV Env-specific CXCR5 ϩ CD4 ϩ T cells that secrete interleukin-21 are strongly associated with B cell memory phenotypes and function. Moreover, we found that the immune responses of HIV controllers showed intrinsically better helper activity than those of HIV progressors.