Glycosylphosphatidylinositol-Anchored Anti-HIV scFv Efficiently Protects CD4 T Cells from HIV-1 Infection and Deletion in hu-PBL Mice

Targeted delivery methods for RNA interference are necessary to obtain a potential functional cure for HIV/AIDS

Ribonucleic acid (RNA) is of great interest in many different therapeutic areas including infectious diseases such as immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Thanks to current, advanced treatments for HIV, the diagnosis is no longer a death sentence. However, even with these treatments, latency is suggested to persist in T-lymphocyte-rich tissues including gut-associated lymphatic tissue (GALT), spleen, and bone marrow making HIV an incurable disease. Therefore, it is important to design systems that can effectively deliver therapeutics to these tissues to fight latent infection and find a functional cure. Numerous therapeutics ranging from small molecules to cell therapies have been explored as a cure for HIV but have failed to maintain therapeutic longevity. RNA interference (RNAi) provides a unique opportunity to achieve a functional cure for those who suffer from chronic HIV/AIDS by suppressing replication of the virus. However, RNA has certain imitations in delivery as it cannot be delivered without a carrier due to its negative charge and degradation from endogenous nucleases. Here, we provide a detailed analysis of explored systems for siRNA delivery for HIV/AIDS in the context of RNA therapeutic design and nanoparticle design. In addition, we suggest strategies that should be used to target specific tissues that are rich in lymphatic tissue.

Humanized Mice for Studies of HIV-1 Persistence and Elimination

A major roadblock to achieving a cure for human immunodeficiency virus type one (HIV-1) is the persistence of latent viral infections in the cells and tissue compartments of an infected human host. Latent HIV-1 proviral DNA persists in resting memory CD4+ T cells and mononuclear phagocytes (MPs; macrophages, microglia, and dendritic cells). Tissue viral reservoirs of both cell types reside in the gut, lymph nodes, bone marrow, spleen, liver, kidney, skin, adipose tissue, reproductive organs, and brain. However, despite the identification of virus-susceptible cells, several limitations persist in identifying broad latent reservoirs in infected persons. The major limitations include their relatively low abundance, the precise identification of latently infected cells, and the lack of biomarkers for identifying latent cells. While primary MP and CD4+ T cells and transformed cell lines are used to interrogate mechanisms of HIV-1 persistence, they often fail to accurately reflect the host cells and tissue environments that carry latent infections. Given the host specificity of HIV-1, there are few animal models that replicate the natural course of viral infection with any precision. These needs underlie the importance of humanized mouse models as both valuable and cost-effective tools for studying viral latency and subsequently identifying means of eliminating it. In this review, we discuss the advantages and limitations of humanized mice for studies of viral persistence and latency with an eye toward using these models to test antiretroviral and excision therapeutics. The goals of this research are to use the models to address how and under which circumstances HIV-1 latency can be detected and eliminated. Targeting latent reservoirs for an ultimate HIV-1 cure is the task at hand.

The Humanized Mouse Model: What Added Value Does It Offer for HIV Research?

In the early 2000s, novel humanized mouse models based on the transplantation of human hematopoietic stem and progenitor cells (HSPCs) into immunocompromised mice were introduced (hu mice). The human HSPCs gave rise to a lymphoid system of human origin. The HIV research community has greatly benefitted from these hu mice. Since human immunodeficiency virus (HIV) type 1 infection results in a high-titer disseminated HIV infection, hu mice have been of great value for all types of HIV research from pathogenesis to novel therapies. Since the first description of this new generation of hu mice, great efforts have been expended to improve humanization by creating other immunodeficient mouse models or supplementing mice with human transgenes to improve human engraftment. Many labs have their own customized hu mouse models, making comparisons quite difficult. Here, we discuss the different hu mouse models in the context of specific research questions in order to define which characteristics should be considered when determining which hu mouse model is appropriate for the question posed. We strongly believe that researchers must first define their research question and then determine whether a hu mouse model exists, allowing the research question to be studied.

Editing out HIV: application of gene editing technology to achieve functional cure

Highly active antiretroviral therapy (HAART) successfully suppresses human immunodeficiency virus (HIV) replication and improves the quality of life of patients living with HIV. However, current HAART does not eradicate HIV infection because an HIV reservoir is established in latently infected cells and is not recognized by the immune system. The successful curative treatment of the Berlin and London patients following bone marrow transplantation inspired researchers to identify an approach for the functional cure of HIV. As a promising technology, gene editing-based strategies have attracted considerable attention and sparked much debate. Herein, we discuss the development of different gene editing strategies in the functional cure of HIV and highlight the potential for clinical applications prospects.

Performance of Affinity-Improved DARPin Targeting HIV Capsid Domain in Interference of Viral Progeny Production

Previously, a designed ankyrin repeat protein, Ank^GAG1D4, was generated for intracellular targeting of the HIV-1 capsid domain. The efficiency was satisfactory in interfering with the HIV assembly process. Consequently, improved Ank^GAG1D4 binding affinity was introduced by substituting tyrosine (Y) for serine (S) at position 45. However, the intracellular anti-HIV-1 activity of Ank^GAG1D4-S45Y has not yet been validated. In this study, the performance of Ank^GAG1D4 and Ank^GAG1D4-S45Y in inhibiting wild-type HIV-1 and HIV-1 maturation inhibitor-resistant replication in SupT1 cells was evaluated. HIV-1 p24 and viral load assays were used to verify the biological activity of Ank^GAG1D4 and Ank^GAG1D4-S45Y as assembly inhibitors. In addition, retardation of syncytium formation in infected SupT1 cells was observed. Of note, the defense mechanism of both ankyrins did not induce the mutation of target amino acids in the capsid domain. The present data show that the potency of Ank^GAG1D4-S45Y was superior to Ank^GAG1D4 in interrupting either HIV-1 wild-type or the HIV maturation inhibitor-resistant strain.

CAIX-specific CAR-T Cells and Sunitinib Show Synergistic Effects Against Metastatic Renal Cancer Models

Treatment with chimeric antigen receptor-modified T cell (CAR-T) has demonstrated promising therapeutic efficacy in hematologic malignancies. However, the therapeutic efficacy is still very limited for solid tumors. An immunosuppressive microenvironment is one of the main reasons for the limited efficacy. Some chemotherapeutic agents exhibit immune microenvironment modulation. Therefore, combination with chemotherapeutic agents may be one of the promising strategies to enhance the therapeutic efficacy of CAR-T against solid tumors. Sunitinib modulates the antitumor immune response by improving T-cell infiltration and function while reducing immunosuppressive factors. The authors constructed a second-generation CAR targeting human renal cell carcinoma (RCC)-specific antigen carbonic anhydrase IX (CAIX) with the costimulatory domain of 4-1BB. The results of cytokine releasing and cell killing assays showed that the CAIX-CAR-T cells have specific effector functions against CAIX renal cancer cells in vitro. Combination therapy with CAIX-CAR-T and sunitinib showed synergistic efficacy against a mouse lung metastasis model of human RCC. CAIX-CAR-T cells in the mice of the combination therapy group showed stronger proliferation and tumor infiltration than that in the mice of the CAIX-CAR-T monotherapy group. The possible mechanisms of the synergistic efficacy are: (1) sunitinib caused upregulation of CAIX in tumor cells; (2) sunitinib decreased frequency of myeloid-derived suppressor cells in the tumor microenvironment. Our study supplied an innovative immunotherapeutic approach whereby combining CAIX-CAR-T with sunitinib induces a potent antitumor response in an experimental model of metastatic RCC. The combination strategy should be considered as a potential approach to augment adoptive CAR-T cell immunotherapy.

Multi-omics analyses reveal that HIV-1 alters CD4+ T cell immunometabolism to fuel virus replication

Individuals infected with human immunodeficiency virus type-1 (HIV-1) show metabolic alterations of CD4⁺ T cells through unclear mechanisms with undefined consequences. We analyzed the transcriptome of CD4⁺ T cells from patients with HIV-1 and revealed that the elevated oxidative phosphorylation (OXPHOS) pathway is associated with poor outcomes. Inhibition of OXPHOS by the US Food and Drug Administration-approved drug metformin, which targets mitochondrial respiratory chain complex-I, suppresses HIV-1 replication in human CD4⁺ T cells and humanized mice. In patients, HIV-1 peak viremia positively correlates with the expression of NLRX1, a mitochondrial innate immune receptor. Quantitative proteomics and metabolic analyses reveal that NLRX1 enhances OXPHOS and glycolysis during HIV-1-infection of CD4⁺ T cells to promote viral replication. At the mechanistic level, HIV infection induces the association of NLRX1 with the mitochondrial protein FASTKD5 to promote expression of mitochondrial respiratory complex components. This study uncovers the OXPHOS pathway in CD4⁺ T cells as a target for HIV-1 therapy.

Generation of HIV-resistant cells with a single-domain antibody: implications for HIV-1 gene therapy

The cure or functional cure of the "Berlin patient" and "London patient" indicates that infusion of HIV-resistant cells could be a viable treatment strategy. Very recently, we genetically linked a short-peptide fusion inhibitor with a glycosylphosphatidylinositol (GPI) attachment signal, rendering modified cells fully resistant to HIV infection. In this study, GPI-anchored m36.4, a single-domain antibody (nanobody) targeting the coreceptor-binding site of gp120, was constructed with a lentiviral vector. We verified that m36.4 was efficiently expressed on the plasma membrane of transduced TZM-bl cells and targeted lipid raft sites without affecting the expression of HIV receptors (CD4, CCR5, and CXCR4). Significantly, TZM-bl cells expressing GPI-m36.4 were highly resistant to infection with divergent HIV-1 subtypes and potently blocked HIV-1 envelope-mediated cell-cell fusion and cell-cell viral transmission. Furthermore, we showed that GPI-m36.4-modified human CEMss-CCR5 cells were nonpermissive to both CCR5- and CXCR4-tropic HIV-1 isolates and displayed a strong survival advantage over unmodified cells. It was found that GPI-m36.4 could also impair HIV-1 Env processing and viral infectivity in transduced cells, underlying a multifaceted mechanism of antiviral action. In conclusion, our studies characterize m36.4 as a powerful nanobody that can generate HIV-resistant cells, offering a novel gene therapy approach that can be used alone or in combination.

CAR T cells: Living HIV drugs

Human immunodeficiency virus type 1 (HIV-1), the virus that causes AIDS (acquired immunodeficiency syndrome), is a major global public health issue. Although the advent of combined antiretroviral therapy (ART) has made significant progress in inhibiting HIV replication in patients, HIV-infected cells remain the principal cellular reservoir of HIV, this allows HIV to rebound immediately upon stopping ART, which is considered the major obstacle to curing HIV infection. Chimeric antigen receptor (CAR) cell therapy has provided new opportunities for HIV treatment. Engineering T cells or hematopoietic stem cells (HSCs) to generate CAR T cells is a rapidly growing approach to develop an efficient immune cell to fight HIV. Herein, we review preclinical and clinical data available for the development of CAR T cells. Further, the advantages and disadvantages of clinical application of anti-HIV CAR T cells will be discussed.

Use of Humanized Mouse Models for Studying HIV-1 Infection, Pathogenesis and Persistence

Despite decades of intensive basic and clinical research efforts, there is still no successful vaccine candidate against human immunodeficiency virus (HIV-1). Standard combined antiretroviral therapy (cART) has been successfully developed and has given remarkable results suppressing HIV-1 infection and transmission. However, cART cannot fully clear the virus from the infected patients. A cure for HIV-1 is highly desirable to stop both the spread of the virus in humans and disease progression in HIV-1 patients. A safe and effective cure strategy for HIV-1 infection will require appropriate animal models that properly mimic HIV-1 infection and advance HIV-1 cure research. Animal models have been a crucial tool in the drug discovery process for investigation of HIV-1 disease mainly in preclinical evaluations of antiretroviral drugs and vaccines. An ideal animal model should recapitulate the main aspects of human-specific HIV-1 infection and pathogenesis with their associated immune responses, while permitting invasive antiretroviral studies. The best humanized mouse models would allow a thorough evaluation of antiretroviral strategies that are aimed towards reducing the establishment and size of the HIV-1 reservoirs. In this review, we evaluate multiple humanized mouse models while presenting their strengths and limitations for HIV-1 research. These humanized mouse models have been tailored in recent decades and heavily employed to address specific quintessential and remaining questions of HIV-1 persistence, pathogenesis and ultimately, eradication.

The Establishment of an In Vivo HIV-1 Infection Model in Humanized B-NSG Mice

Suitable animal models for human immunodeficiency virus type 1 (HIV-1) infection are important for elucidating viral pathogenesis and evaluating antiviral strategies in vivo. The B-NSG (NOD-PrkdcscidIl2rgtm1/Bcge) mice that have severe immune defect phenotype are examined for the suitability of such a model in this study. Human peripheral blood mononuclear cells (PBMCs) were engrafted into B-NSG mice via mouse tail vein injection, and the repopulated human T-lymphocytes were observed at as early as 3-weeks post-transplantation in mouse peripheral blood and several tissues. The humanized mice could be infected by HIV-1, and the infection recapitulated features of T-lymphocyte dynamic observed in HIV-1 infected humans, meanwhile the administration of combination antiretroviral therapy (cART) suppressed viral replication and restored T lymphocyte abnormalities. The establishment of HIV-1 infected humanized B-NSG mice not only provides a model to study virus and T cell interplays, but also can be a useful tool to evaluate antiviral strategies.

Humanized mice are precious tools for evaluation of hematopoietic gene therapies and preclinical modeling to move towards a clinical trial

Over the last decade, incrementally improved xenograft mouse models, which support the engraftment and development of a human hemato-lymphoid system, have been developed and represent an important fundamental and preclinical research tool. Immunodeficient mice can be transplanted with human hematopoietic stem cells (HSCs) and this process is accompanied by HSC homing to the murine bone marrow. This is followed by stem cell expansion, multilineage hematopoiesis, long-term engraftment, and functional human antibody and cellular immune responses. The most significant contributions made by these humanized mice are the identification of normal and leukemic hematopoietic stem cells, the characterization of the human hematopoietic hierarchy, screening of anti-cancer therapies and their use as preclinical models for gene therapy applications. This review article focuses on several gene therapy applications that have benefited from evaluation in humanized mice such as chimeric antigen receptor (CAR) T cell therapies for cancer, anti-viral therapies and gene therapies for multiple monogenetic diseases. Humanized mouse models have been and still are of great value for the gene therapy field since they provide a more reliable understanding of sometimes complicated therapeutic approaches such as recently developed therapeutic gene editing strategies, which seek to correct a gene at its endogenous genomic locus. Additionally, humanized mouse models, which are of great importance with regard to testing new vector technologies in vivo for assessing safety and efficacy prior toclinical trials, help to expedite the critical translation from basic findings to clinical applications. In this review, innovative gene therapies and preclinical studies to evaluate T- and B-cell and HSC-based therapies in humanized mice are discussed and illustrated by multiple examples.

A Membrane-Anchored Short-Peptide Fusion Inhibitor Fully Protects Target Cells from Infections of Human Immunodeficiency Virus Type 1 (HIV-1), HIV-2, and Simian Immunodeficiency Virus

Emerging studies demonstrate that the antiviral activity of viral fusion inhibitor peptides can be dramatically improved when being chemically or genetically anchored to the cell membrane, where viral entry occurs. We previously reported that the short-peptide fusion inhibitor 2P23 and its lipid derivative possess highly potent antiviral activities against human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). To develop a sterilizing or functional-cure strategy, here we genetically linked 2P23 and two control peptides (HIV-1 fusion inhibitor C34 and hepatitis B virus [HBV] entry inhibitor 4B10) with a glycosylphosphatidylinositol (GPI) attachment signal. As expected, GPI-anchored inhibitors were efficiently expressed on the plasma membrane of transduced TZM-bl cells and primarily directed to the lipid raft site without interfering with the expression of CD4, CCR5, and CXCR4. GPI-anchored 2P23 (GPI-2P23) completely protected TZM-bl cells from infections of divergent HIV-1, HIV-2, and SIV isolates as well as a panel of enfuvirtide (T20)-resistant mutants. GPI-2P23 also rendered the cells resistant to viral envelope-mediated cell-cell fusion and cell-associated virion-mediated cell-cell transmission. Moreover, GPI-2P23-modified human CD4⁺ T cells (CEMss-CCR5) fully blocked both R5- and X4-tropic HIV-1 isolates and displayed a robust survival advantage over unmodified cells during HIV-1 infection. In contrast, it was found that GPI-anchored C34 was much less effective in inhibiting HIV-2, SIV, and T20-resistant HIV-1 mutants. Therefore, our studies have demonstrated that genetically anchoring a short-peptide fusion inhibitor to the target cell membrane is a viable strategy for gene therapy of both HIV-1 and HIV-2 infections.IMPORTANCE Antiretroviral therapy with multiple drugs in combination can efficiently suppress HIV replication and dramatically reduce the morbidity and mortality associated with AIDS-related illness; however, antiretroviral therapy cannot eradiate the HIV reservoirs, and lifelong treatment is required, which often results in cumulative toxicities, drug resistance, and a multitude of complications, thus necessitating the development of sterilizing-cure or functional-cure strategies. Here, we report that genetically anchoring the short-peptide fusion inhibitor 2P23 to the cell membrane can fully prevent infections from divergent HIV-1, HIV-2, and SIV isolates as well as a panel of enfuvirtide-resistant mutants. Membrane-bound 2P23 also effectively blocks HIV-1 Env-mediated cell-cell fusion and cell-associated virion-mediated cell-cell transmission, renders CD4⁺ T cells nonpermissive to infection, and confers a robust survival advantage over unmodified cells. Thus, our studies verify a powerful strategy to generate resistant cells for gene therapy of both the HIV-1 and HIV-2 infections.

Vpr Enhances HIV-1 Env Processing and Virion Infectivity in Macrophages by Modulating TET2-Dependent IFITM3 Expression

HIV-1 Vpr enhances viral replication in human macrophages via multiple mechanisms that are not clearly defined. It does not affect HIV-1 virion production during the first round of infection. We have recently discovered that Vpr targets the DNA demethylase TET2 for degradation, which leads to sustained interleukin-6 (IL-6) expression and elevated HIV-1 replication. We report here that Vpr enhanced Env processing in infected macrophages, associated with increased Env incorporation into virions with higher infectivity. Interestingly, IFITM3 was constitutively expressed in macrophages in a TET2-dependent fashion. We showed that Vpr-enhanced Env processing depended genetically on TET2 and IFITM3. We further showed that Vpr reduced IFITM3 expression by reducing demethylation of the IFITM3 promoter in macrophages, associated with degradation of TET2 and reduced TET2 binding to the IFITIM3 promoter. Our findings indicate that the Vpr-TET2 axis enhances HIV-1 replication in macrophages via two independent mechanisms: reduced IFTIM3 expression to enhance Env processing and virion infectivity and sustained IL-6 expression to increase HIV-1 replication. The Vpr-TET2 axis may provide a novel target to develop therapeutics to inhibit HIV-1 infection and pathogenesis.IMPORTANCE How Vpr enhances HIV-1 replication in macrophages is still unclear. We report here that Vpr enhanced HIV-1 Env processing during the first round of HIV-1 replication, resulting in virions with higher Env incorporation and viral infectivity. These higher-quality viral particles contributed to elevated infection during the second round and spreading infection in macrophages and other HIV-1 target cells. We have recently discovered that TET2 is a novel host factor degraded by Vpr, which leads to sustained IL-6 expression in macrophages. Interestingly, Vpr-enhanced HIV-1 Env processing depended on both the IFITIM3 and TET2 genes. The constitutive expression of IFITIM3 expression in macrophages was maintained by TET2, which demethylated the IFITIM3 promoter. We conclude that the Vpr degrades TET2 to enhance HIV-1 replication in macrophages by reducing IFITIM3 expression to increase viral Env processing, virion incorporation, and infectivity and by sustaining IL-6 expression to increase HIV-1 gene expression. The Vpr-TET2 axis may serve as a novel target to develop anti-HIV drugs to inhibit HIV-1 infection and pathogenesis.

Suppression of Active HIV-1 Infection in CD34+ Hematopoietic Humanized NSG Mice by a Combination of Combined Antiretroviral Therapy and CCR5 Targeting Drugs

Significant progress has been made in the diagnostics and treatment of AIDS since the discovery of the human immunodeficiency virus type 1 (HIV-1) in 1983. The remarkable effectiveness of combined antiretroviral therapy (cART) is evidenced by mortality reduction, control of peripheral blood viral load, and in a nearly normal quality of HIV patients' lives. Remaining obstacles in treatment and cure are drug toxicities and side effects, viral resistance, persistence of HIV-1 reservoirs on termination of cART treatment, the cost of lifelong antiretroviral therapy, and the stigma associated with taking antiretroviral drugs. As determined by plasma viral RNA and peripheral blood mononuclear cells (PBMC) proviral DNA, we show improved suppression of productive HIV infection in human CD34⁺ hematopoietic stem cell-engrafted NOD (nonobese diabetic)-SCID (severe combined immunodeficiency)-il2rg^-/- (NSG) mice by combined treatment with cART and CCR5 targeting drugs, compared with cART alone, as well as an increased preservation of human CD4⁺ T cells (defined as CD45⁺ CD3⁺ CD4⁺ cells) and CD4⁺/CD8⁺ cell ratios in infected mice. The data also suggest a possible reduction in viral reservoirs. Our data confirm that this animal model is suitable for detection of productive HIV infection, replication, and establishment of viral reservoirs. The data also provide proof of principle for the utility of combining CCR5 targeting drugs, maraviroc and rapamycin, with traditional cART to improve control of viremia and reduce viral reservoirs. This study thus serves as a model for future HIV-1 studies that could lead to the clinical development of new generations of antiretroviral drugs.

Glycosyl-Phosphatidylinositol-Anchored Anti-HIV Env Single-Chain Variable Fragments Interfere with HIV-1 Env Processing and Viral Infectivity

In previous studies, we demonstrated that single-chain variable fragments (scFvs) from anti-human immunodeficiency virus (HIV) Env monoclonal antibodies act as entry inhibitors when tethered to the surface of target cells by a glycosyl-phosphatidylinositol (GPI) anchor. Interestingly, even if a virus escapes inhibition at entry, its replication is ultimately controlled. We hypothesized that in addition to functioning as entry inhibitors, anti-HIV GPI-scFvs may also interact with Env in an infected cell, thereby interfering with the infectivity of newly produced virions. Here, we show that expression of the anti-HIV Env GPI-scFvs in virus-producing cells reduced the release of HIV from cells 5- to 22-fold, and infectivity of the virions that were released was inhibited by 74% to 99%. Additionally, anti-HIV Env GPI-scFv X5 inhibited virion production and infectivity after latency reactivation and blocked transmitter/founder virus production and infectivity in primary CD4⁺ T cells. In contrast, simian immunodeficiency virus (SIV) production and infectivity were not affected by the anti-HIV Env GPI-scFvs. Loss of infectivity of HIV was associated with a reduction in the amount of virion-associated Env gp120. Interestingly, an analysis of Env expression in cell lysates demonstrated that the anti-Env GPI-scFvs interfered with processing of Env gp160 precursors in cells. These data indicate that GPI-scFvs can inhibit Env processing and function, thereby restricting production and infectivity of newly synthesized HIV. Anti-Env GPI-scFvs therefore appear to be unique anti-HIV molecules as they derive their potent inhibitory activity by interfering with both early (receptor binding/entry) and late (Env processing and incorporation into virions) stages of the HIV life cycle.IMPORTANCE The restoration of immune function and persistence of CD4⁺ T cells in HIV-1-infected individuals without antiretroviral therapy requires a way to increase resistance of CD4⁺ T cells to infection by both R5- and X4-tropic HIV-1. Previously, we reported that anchoring anti-HIV-1 single-chain variable fragments (scFvs) via glycosyl-phosphatidylinositol (GPI) to the surface of permissive cells conferred a high level of resistance to HIV-1 variants at the level of entry. Here, we report that anti-HIV GPI-scFvs also derive their potent antiviral activity in part by blocking HIV production and Env processing, which consequently inhibits viral infectivity even in primary infection models. Thus, we conclude that GPI-anchored anti-HIV scFvs derive their potent blocking activity of HIV replication by interfering with successive stages of the viral life cycle. They may be effectively used in genetic intervention of HIV-1 infection.

Current Peptide and Protein Candidates Challenging HIV Therapy beyond the Vaccine Era

Human immunodeficiency virus (HIV) is a causative agent of acquired immune deficiency syndrome (AIDS). Highly active antiretroviral therapy (HAART) can slow down the replication of HIV-1, leading to an improvement in the survival of HIV-1-infected patients. However, drug toxicities and poor drug administration has led to the emergence of a drug-resistant strain. HIV-1 immunotherapy has been continuously developed, but antibody therapy and HIV vaccines take time to improve its efficiency and have limitations. HIV-1-specific chimeric antigen receptor (CAR)-based immunotherapy founded on neutralizing antibodies is now being developed. In HIV-1 therapy, anti-HIV chimeric antigen receptors showed promising data in the suppression of HIV-1 replication; however, autologous transfusion is still a problem. This has led to the development of effective peptides and proteins for an alternative HIV-1 treatment. In this paper, we provide a comprehensive review of potent anti-HIV-1 peptides and proteins that reveal promising therapeutic activities. The inhibitory mechanisms of each therapeutic molecule in the different stages of the HIV-1 life cycle will be discussed herein.

New approaches for the enhancement of chimeric antigen receptors for the treatment of HIV

HIV infection continues to be a life-long chronic disease in spite of the success of antiretroviral therapy (ART) in controlling viral replication and preventing disease progression. However, because of the high cost of treatment, severe side effects, and inefficiency in curing the disease with ART, there is a call for alternative therapies that will provide a functional cure for HIV. Cytotoxic T lymphocytes (CTLs) are vital in the control and clearance of viral infections and therefore immune-based therapies have attempted to engineer HIV-specific CTLs that would be able to clear the infection from the body. The development of chimeric antigen receptors (CARs) provides an opportunity to engineer superior HIV-specific CTLs that will be independent of the major histocompatibility complex for target recognition. A CD4-based CAR has been previously tested in clinical trials to test the antiviral efficacy of peripheral T cells armed with this CD4-based CAR. The results from these clinical trials showed the safety and feasibility of CAR T cell therapy for HIV infection; however, minimal antiviral efficacy was seen. In this review, we will discuss the various strategies being developed to enhance the therapeutic potency of anti-HIV CARs with the goal of generating superior antiviral responses that will lead to life-long HIV immunity and clearance of the virus from the body.