Evidence for HIV-1 cure after CCR5Δ32/Δ32 allogeneic haemopoietic stem-cell transplantation 30 months post analytical treatment interruption: a case report

Adeno-Associated Virus (AAV)-Delivered Exosomal TAT and BiTE Molecule CD4-αCD3 Facilitate the Elimination of CD4 T Cells Harboring Latent HIV-1

Combinatorial antiretroviral therapy (cART) has transformed HIV infection from a death sentence to a controllable chronic disease, but cannot eliminate the virus. Latent HIV-1 reservoirs are the major obstacles to cure HIV-1 infection. Previously, we engineered exosomal Tat (Exo-Tat) to reactivate latent HIV-1 from the reservoir of resting CD4+ T cells. Here, we present an HIV-1 eradication platform, which uses our previously described Exo-Tat to activate latent virus from resting CD4+ T cells guided by the specific binding domain of CD4 in interleukin 16 (IL16), attached to the N-terminus of exosome surface protein lysosome-associated membrane protein 2 variant B (Lamp2B). Cells with HIV-1 surface protein gp120 expressed on the cell membranes are then targeted for immune cytolysis by a BiTE molecule CD4-αCD3, which colocalizes the gp120 surface protein of HIV-1 and the CD3 of cytotoxic T lymphocytes. Using primary blood cells obtained from antiretroviral treated individuals, we find that this combined approach led to a significant reduction in replication-competent HIV-1 in infected CD4+ T cells in a clonal in vitro cell system. Furthermore, adeno-associated virus serotype DJ (AAV-DJ) was used to deliver Exo-Tat, IL16lamp2b and CD4-αCD3 genes by constructing them in one AAV-DJ vector (the plasmid was named pEliminator). The coculture of T cells from HIV-1 patients with Huh-7 cells infected with AAV-Eliminator viruses led to the clearance of HIV-1 reservoir cells in the in vitro experiment, which could have implications for reducing the viral reservoir in vivo, indicating that Eliminator AAV viruses have the potential to be developed into therapeutic biologics to cure HIV-1 infection.

Modelling HIV-1 control and remission

Remarkable advances are being made in developing interventions for eliciting long-term remission of HIV-1 infection. The success of these interventions will obviate the need for lifelong antiretroviral therapy, the current standard-of-care, and benefit the millions living today with HIV-1. Mathematical modelling has made significant contributions to these efforts. It has helped elucidate the possible mechanistic origins of natural and post-treatment control, deduced potential pathways of the loss of such control, quantified the effects of interventions, and developed frameworks for their rational optimization. Yet, several important questions remain, posing challenges to the translation of these promising interventions. Here, we survey the recent advances in the mathematical modelling of HIV-1 control and remission, highlight their contributions, and discuss potential avenues for future developments.

Hematopoietic stem cell transplantation and cellular therapy in persons living with HIV

PURPOSE OF REVIEW

Summarize the latest research of both stem cell transplantation and cellular therapy and present the implications with respect to persons with HIV (PWH), hematologic malignancies, and HIV-1 cure.

RECENT FINDINGS

Allogeneic (alloSCT) and autologous (autoSCT) stem cell transplantation have been shown to be well tolerated and effective regardless of HIV-1 status. AlloSCT leads to a decrease in the HIV-1 latently infected reservoir orders of magnitude below that achieved with antiretroviral therapy (ART) alone. Utilization of CCR5Δ2/Δ32 donors in an alloSCT has resulted in HIV-1 cures. In the last 12 months, three cases of cure have been published, giving further insight into the conditions required for HIV-1 control. Other advances in the treatment of hematological cancers include chimeric antigen receptor T-cell (CART) therapy, which are active in PWH with lymphoma.

SUMMARY

Here we discuss the advances in SCT and cellular therapy in PWH and cancer. Additionally, we discuss how these technologies are being utilized to achieve HIV-1 cure.

Impact of alemtuzumab-mediated lymphocyte depletion on SIV reservoir establishment and persistence

Persistence of the rebound-competent viral reservoir (RCVR) within the CD4+ T cell compartment of people living with HIV remains a major barrier to HIV cure. Here, we determined the effects of the pan-lymphocyte-depleting monoclonal antibody (mAb) alemtuzumab on the RCVR in SIVmac239-infected rhesus macaques (RM) receiving antiretroviral therapy (ART). Alemtuzumab administered during chronic ART or at the time of ART initiation induced >95% depletion of circulating CD4+ T cells in peripheral blood and substantial CD4+ T cell depletion in lymph nodes. However, treatment was followed by proliferation and reconstitution of CD4+ T cells in blood, and despite ongoing ART, levels of cell-associated SIV DNA in blood and lymphoid tissues were not substantially different between alemtuzumab-treated and control RM after immune cell reconstitution, irrespective of the time of alemtuzumab treatment. Upon ART cessation, 19 of 22 alemtuzumab-treated RM and 13 of 13 controls rebounded with no difference in the time to rebound between treatment groups. Time to rebound and reactivation rate was associated with plasma viral loads (pVLs) at time of ART initiation, suggesting lymphocyte depletion had no durable impact on the RCVR. However, 3 alemtuzumab-treated RM that had lowest levels of pre-ART viremia, failed to rebound after ART withdrawal, in contrast to controls with similar levels of SIV replication. These observations suggest that alemtuzumab therapy has little to no ability to reduce well-established RCVRs but may facilitate RCVR destabilization when pre-ART virus levels are particularly low.

Plasma, intracellular and lymph node antiretroviral concentrations and HIV DNA change during primary HIV infection: Results from the INACTION P25 study

Despite its effectiveness, combination antiretroviral treatment (cART) has a limited effect on HIV DNA reservoir, which establishes early during primary HIV infection (PHI) and is maintained by latency, homeostatic T-cells proliferation, and residual replication. This limited effect can be associated with low drug exposure in lymphoid tissues and/or suboptimal adherence to antiretroviral drugs (ARVs). The aim of this study was to assess ARV concentrations in plasma, peripheral blood mononuclear cells (PBMCs) and lymph nodes (LNs), and their association to HIV RNA and HIV DNA decay during PHI. Participants were randomised to receive standard doses of darunavir/cobicistat (Arm I), dolutegravir (Arm II) or both (Arm III), with a backbone of tenofovir alafenamide and emtricitabine. Total HIV DNA was measured using digital-droplet PCR in PBMCs at baseline, 12 and 48 weeks. Drug concentrations in plasma and PBMCs were determined at 2, 12 and 48 weeks (LNs at 12 weeks) by UHPLC-MS/MS. Seventy-two participants were enrolled, mostly male (n=68), with a median age of 34 years and variable Fiebig stages (V-VI 57.7%, I-II 23.9%, and III-IV 18.3%). Twenty-six patients were assigned to Arm I, 27 to Arm II and 19 to Arm III. After 48 weeks, most patients had undetectable viremia, with minor differences in HIV RNA decay between arms. Patients with Fiebig I-II showed faster HIV RNA and HIV DNA decay. Intracellular tissue penetration was high for nucleoside analogues and low-moderate for darunavir and dolutegravir. Only tenofovir diphosphate concentrations in PBMCs showed correlation with HIV DNA decay. Overall, these results indicate that the timing of treatment initiation and intracellular tenofovir penetration are primary and secondary factors, respectively, affecting HIV reservoir.

CCR5Δ32 and HLA allele diversity in bone marrow donors from southern Brazil

Transplantation of stem cells derived from donors with CCR5Δ32 homozygous genotype is a potential strategy to achieve both the control of malignant hematological disease as well as sustained remission of the HIV infection, and researchers in different countries are looking for CCR5Δ32 homozygous donors to replicate such a 'double-target' strategy. We determined the frequency of the CCR5Δ32 variant in a sample of 1,398 bone marrow donors from Rio Grande do Sul State, Brazil. This study also evaluated whether HLA-A, HLA-B and HLA-DRB1 genotypes are homogeneously distributed between CCR5Δ32 carriers and non-carriers in a population characterized by a significant genetic admixture. The CCR5Δ32 allele frequency was 7.4% (CI0.95 6.4-8.4%), and the frequency of the Δ32/Δ32 homozygous genotype was 0.72% (CI0.95 0.34-1.31%). In general, HLA genotypes are homogeneously distributed between CCR5Δ32 carriers and non-carriers. Considering the large number of bone marrow donors in Brazil and the high CCR5Δ32 allele frequency observed in our study, our results clearly indicate the existence of a considerable amount of potential CCR5Δ32 homozygous bone marrow donors in southern Brazil, suggesting that an active search for these donors is not only feasible but an attractive and promising strategy towards effective HIV infection control and treatment.

HIV Persistence, Latency, and Cure Approaches: Where Are We Now?

The latent reservoir remains a major roadblock to curing human immunodeficiency virus (HIV) infection. Currently available antiretroviral therapy (ART) can suppress active HIV replication, reduce viral loads to undetectable levels, and halt disease progression. However, antiretroviral drugs are unable to target cells that are latently infected with HIV, which can seed viral rebound if ART is stopped. Consequently, a major focus of the field is to study the latent viral reservoir and develop safe and effective methods to eliminate it. Here, we provide an overview of the major mechanisms governing the establishment and maintenance of HIV latency, the key challenges posed by latent reservoirs, small animal models utilized to study HIV latency, and contemporary cure approaches. We also discuss ongoing efforts to apply these approaches in combination, with the goal of achieving a safe, effective, and scalable cure for HIV that can be extended to the tens of millions of people with HIV worldwide.

Advanced Therapies for Human Immunodeficiency Virus

Human Immunodeficiency Virus (HIV) remains a significant global health challenge with approximately 38 million people currently having the virus worldwide. Despite advances in treatment development, the virus persists in the human population and still leads to new infections. The virus has a powerful ability to mutate and hide from the human immune system in reservoirs of the body. Current standard treatment with antiretroviral therapy effectively controls viral replication but requires lifelong adherence and does not eradicate the virus. This review explores the potential of Advanced Therapy Medicinal Products as novel therapeutic approaches to HIV, including cell therapy, immunisation strategies and gene therapy. Cell therapy, particularly chimeric antigen receptor T cell therapy, shows promise in preclinical studies for targeting and eliminating HIV-infected cells. Immunisation therapies, such as broadly neutralising antibodies are being investigated to control viral replication and reduce reservoirs. Despite setbacks in recent trials, vaccines remain a promising avenue for HIV therapy development. Gene therapy using technologies like CRISPR/Cas9 aims to modify cells to resist HIV infection or eliminate infected cells. Challenges such as off-target effects, delivery efficiency and ethical considerations persist in gene therapy for HIV. Future directions require further research to assess the safety and efficacy of emerging therapies in clinical trials. Combined approaches may be necessary to achieve complete elimination of the HIV reservoir. Overall, advanced therapies offer new hope for advancing HIV treatment and moving closer to a cure.

Tat-dependent conditionally replicating adenoviruses expressing diphtheria toxin A for specifically killing HIV-1-infected cells

HIV-1 infection remains a public health problem with no cure. Although antiretroviral therapy (ART) is effective for suppressing HIV-1 replication, it requires lifelong drug administration due to a stable reservoir of latent proviruses and may cause serious side effects and drive the emergence of drug-resistant HIV-1 variants. Gene therapy represents an alternative approach to overcome the limitations of conventional treatments against HIV-1 infection. In this study, we constructed and investigated the antiviral effects of an HIV-1 Tat-dependent conditionally replicating adenovirus, which selectively replicates and expresses the diphtheria toxin A chain (Tat-CRAds-DTA) in HIV-1-infected cells both in vitro and in vivo. We found that Tat-CRAds-DTA could specifically induce cell death and inhibit virus replication in HIV-1-infected cells mediated by adenovirus proliferation and DTA expression. A low titer of progeny Tat-CRAds-DTA was also detected in HIV-1-infected cells. In addition, Tat-CRAds-DTA showed no apparent cytotoxicity to HIV-1-negative cells and demonstrated significant therapeutic efficacy against HIV-1 infection in a humanized mouse model. The findings in this study highlight the potential of Tat-CRAds-DTA as a new gene therapy for the treatment of HIV-1 infection.

The fulfilled promise and unmet potential of umbilical cord blood

PURPOSE OF REVIEW

Here, we review classic and emerging uses of umbilical cord blood and highlight strategies to improve its utility, focusing on selection of the appropriate units and cell types for the intended applications.

RECENT LITERATURE

Recent studies have shown advancements in cord blood cell utility in a variety of cellular therapies and have made strides in elucidating manners to select the best units for therapy and target new ways to improve the various cell subpopulations for their respective applications.

SUMMARY

Umbilical cord blood is a proven source of cells for hematopoietic cell transplantation and research and is an important potential source for additional cellular therapies. However, cord blood utility is limited by low "doses" of potent cells that can be obtained from individual units, a limitation that is specific to cord blood as a donor source. In addition to traditional CD34 + progenitor cells, cord blood lymphocytes are being pursued as therapeutic entities with their own unique properties and characteristics. Thus, selection of ideal units depends on the intended therapeutic entity and target, and identification of differential potency parameters is critical to drive effective banking strategies accommodating successful clinical use of cord blood in broader cell therapy settings.

Gaining momentum: stem cell therapies for HIV cure

PURPOSE OF REVIEW

Durable HIV-1 remission has been reported in a person who received allogeneic stem cell transplants (SCTs) involving CCR5 Δ32/Δ32 donor cells. Much of the reduction in HIV-1 burden following allogeneic SCT with or without donor cells inherently resistant to HIV-1 infection is likely due to cytotoxic graft-versus-host effects on residual recipient immune cells. Nonetheless, there has been growing momentum to develop and implement stem cell therapies that lead to durable long-term antiretroviral therapy (ART)-free remission without the need for SCT.

RECENT FINDINGS

Most current research leverages gene editing techniques to modify hematopoietic stem cells which differentiate into immune cells capable of harboring HIV-1. Approaches include targeting genes that encode HIV-1 co-receptors using Zinc Finger Nucleases (ZFN) or CRISPR-Cas-9 to render a pool of adult or progenitor cells resistant to de-novo infection. Other strategies involve harnessing multipotent mesenchymal stromal cells to foster immune environments that can more efficiently recognize and target HIV-1 while promoting tissue homeostasis.

SUMMARY

Many of these strategies are currently in a state of infancy or adolescence; nonetheless, promising preclinical and first-in-human studies have been performed, providing further rationale to focus resources on stem cell therapies.

Dynamics of virological and immunological markers of HIV persistence after allogeneic haematopoietic stem-cell transplantation in the IciStem cohort: a prospective observational cohort study

BACKGROUND

Allogeneic haematopoietic stem-cell transplantation (allo-HSCT) markedly reduces HIV reservoirs, but the mechanisms by which this occurs are only partly understood. In this study, we aimed to describe the dynamics of virological and immunological markers of HIV persistence after allo-HSCT.

METHODS

In this prospective observational cohort study, we analysed the viral reservoir and serological dynamics in IciStem cohort participants with HIV who had undergone allo-HSCT and were receiving antiretroviral therapy, ten of whom had received cells from donors with the CCR5Δ32 mutation. Participants from Belgium, Canada, Germany, Italy, the Netherlands, Spain, Switzerland, and the UK were included in the cohort both prospectively and retrospectively between June 1, 2014 and April 30, 2019. In the first 6 months after allo-HSCT, participants had monthly assessments, with annual assessments thereafter, with the protocol tailored to accommodate for the individual health status of each participant. HIV reservoirs were measured in blood and tissues and HIV-specific antibodies were measured in plasma. We used the Wilcoxon signed-rank test to compare data collected before and after allo-HSCT in participants for whom longitudinal data were available. When the paired test was not possible, we used the Mann-Whitney U test. We developed a mathematical model to study the factors influencing HIV reservoir reduction in people with HIV after allo-HSCT.

FINDINGS

We included 30 people with HIV with haematological malignancies who received a transplant between Sept 1, 2009 and April 30, 2019 and were enrolled within the IciStem cohort and included in this analysis. HIV reservoirs in peripheral blood were reduced immediately after full donor chimerism was achieved, generally accompanied by undetectable HIV-DNA in bone marrow, ileum, lymph nodes, and cerebrospinal fluid, regardless of donor CCR5 genotype. HIV-specific antibody levels and functionality values declined more slowly than direct HIV reservoir values, decaying significantly only months after full donor chimerism. Mathematical modelling suggests that allogeneic immunity mediated by donor cells is the main viral reservoir depletion mechanism after massive reservoir reduction during conditioning chemotherapy before allo-HSCT (half-life of latently infected replication-competent cells decreased from 44 months to 1·5 months).

INTERPRETATION

Our work provides, for the first time, data on the effects of allo-HSCT in the context of HIV infection. Additionally, we raise the question of which marker can serve as the last reporter of the residual viraemia, postulating that the absence of T-cell immune responses might be a more reliable marker than antibody decline after allo-HSCT.

FUNDING

amfAR (American Foundation for AIDS Research; ARCHE Program), National Institutes of Health, National Institute of Allergy and Infectious Diseases, and Dutch Aidsfonds.

A simultaneous knockout knockin genome editing strategy in HSPCs potently inhibits CCR5- and CXCR4-tropic HIV-1 infection

Allogeneic hematopoietic stem and progenitor cell transplant (HSCT) of CCR5 null (CCR5Δ32) cells can be curative for HIV-1-infected patients. However, because allogeneic HSCT poses significant risk, CCR5Δ32 matched bone marrow donors are rare, and CCR5Δ32 transplant does not confer resistance to the CXCR4-tropic virus, it is not a viable option for most patients. We describe a targeted Cas9/AAV6-based genome editing strategy for autologous HSCT resulting in both CCR5- and CXCR4-tropic HIV-1 resistance. Edited human hematopoietic stem and progenitor cells (HSPCs) maintain multi-lineage repopulation capacity in vivo, and edited primary human T cells potently inhibit infection by both CCR5-tropic and CXCR4-tropic HIV-1. Modification rates facilitated complete loss of CCR5-tropic replication and up to a 2,000-fold decrease in CXCR4-tropic replication without CXCR4 locus disruption. This multi-factor editing strategy in HSPCs could provide a broad approach for autologous HSCT as a functional cure for both CCR5-tropic and CXCR4-tropic HIV-1 infections.

Stem cell-derived CAR T cells show greater persistence, trafficking, and viral control compared to ex vivo transduced CAR T cells

Adoptive cell therapy (ACT) using T cells expressing chimeric antigen receptors (CARs) is an area of intense investigation in the treatment of malignancies and chronic viral infections. One of the limitations of ACT-based CAR therapy is the lack of in vivo persistence and maintenance of optimal cell function. Therefore, alternative strategies that increase the function and maintenance of CAR-expressing T cells are needed. In our studies using the humanized bone marrow/liver/thymus (BLT) mouse model and nonhuman primate (NHP) model of HIV infection, we evaluated two CAR-based gene therapy approaches. In the ACT approach, we used cytokine enhancement and preconditioning to generate greater persistence of anti-HIV CAR+ T cells. We observed limited persistence and expansion of anti-HIV CAR T cells, which led to minimal control of the virus. In our stem cell-based approach, we modified hematopoietic stem/progenitor cells (HSPCs) with anti-HIV CAR to generate anti-HIV CAR T cells in vivo. We observed CAR-expressing T cell expansion, which led to better plasma viral load suppression. HSPC-derived CAR cells in infected NHPs showed superior trafficking and persistence in multiple tissues. Our results suggest that a stem cell-based CAR T cell approach may be superior in generating long-term persistence and functional antiviral responses against HIV infection.

Dysbiosis of gut microbiota and metabolites during AIDS: implications for CD4 + T cell reduction and immune activation

OBJECTIVE

Identifying the gut microbiota associated with host immunity in the AIDS stage.

DESIGN

We performed a cross-sectional study.

METHODS

We recruited people with HIV (PWH) in the AIDS or non-AIDS stage and evaluated their gut microbiota and metabolites by using 16S ribosomal RNA (rRNA) sequencing and liquid chromatography-mass spectrometry (LC-MS). Machine learning models were used to analyze the correlations between key bacteria and CD4 + T cell count, CD4 + T cell activation, bacterial translocation, gut metabolites, and KEGG functional pathways.

RESULTS

We recruited 114 PWH in the AIDS stage and 203 PWH in the non-AIDS stage. The α-diversity of gut microbiota was downregulated in the AIDS stage ( P  < 0.05). Several machine learning models could be used to identify key gut microbiota associated with AIDS, including the logistic regression model with area under the curve (AUC), sensitivity, specificity, and Brier scores of 0.854, 0.813, 0.813, and 0.160, respectively. The decreased key bacteria ASV1 ( Bacteroides sp.), ASV8 ( Fusobacterium sp.), ASV30 ( Roseburia sp.), ASV37 ( Bacteroides sp.), and ASV41 ( Lactobacillus sp.) in the AIDS stage were positively correlated with the CD4 + T cell count, the EndoCAb IgM level, 4-hydroxyphenylpyruvic acid abundance, and the predicted cell growth pathway, and negatively correlated with the CD3 + CD4 + CD38 + HLA-DR + T cell count and the sCD14 level.

CONCLUSION

Machine learning has the potential to recognize key gut microbiota related to AIDS. The key five bacteria in the AIDS stage and their metabolites might be related to CD4 + T cell reduction and immune activation.

CAR-T Cell Therapy: Advances in Kidney-Related Diseases

Background

Chimeric antigen receptor (CAR)-T cell therapy represents a significant advancement in the field of immunotherapy, providing targeted eradication of abnormal cells through the recognition between CAR and target antigens. This approach has garnered considerable attention due to its promising results in the clinical treatment of hematological malignancies and autoimmune diseases. As the focus shifts toward exploring novel targets and expanding the application of CAR-T cell therapy to solid tumors, including renal malignancies, researchers are pushing the boundaries of this innovative treatment. However, it is crucial to address the observed comorbidities associated with CAR-T cell therapy, particularly nephrotoxicity, due to the superseding release of cytokines and impairment of normal tissue.

Summary

Our review discusses the research strategies and nephrotoxicity related to CAR-T cell therapy in various kidney-related diseases and provides insights into enhancing investigation and optimization.

Key Messages

CAR-T cell therapy has captured the attention of researchers and clinicians in the treatment of renal malignancies, multiple myeloma, systemic lupus erythematosus, and acquired immunodeficiency syndrome, which may lead to potential nephrotoxicity as they involve primary or secondary kidney complications. Understanding and summarizing the current research progress of CAR-T cell therapies can provide valuable insights into novel targets and combinations to optimize research models and enhance their clinical value.

Legacy of a magic gene-CCR5-∆32: From discovery to clinical benefit in a generation

The discovery of the 32-bp deletion allele of the chemokine receptor gene CCR5 showed that homozygous carriers display near-complete resistance to HIV infection, irrespective of exposure. Algorithms of molecular evolutionary theory suggested that the CCR5-∆32 mutation occurred but once in the last millennium and rose by strong selective pressure relatively recently to a ~10% allele frequency in Europeans. Several lines of evidence support the hypothesis that CCR5-∆32 was selected due to its protective influence to resist Yersinia pestis, the agent of the Black Death/bubonic plague of the 14th century. Powerful anti-AIDS entry inhibitors targeting CCR5 were developed as a treatment for HIV patients, particularly those whose systems had developed resistance to powerful anti-retroviral therapies. Homozygous CCR5-∆32/∆32 stem cell transplant donors were used to produce HIV-cleared AIDS patients in at least five "cures" of HIV infection. CCR5 has also been implicated in regulating infection with Staphylococcus aureus, in recovery from stroke, and in ablation of the fatal graft versus host disease (GVHD) in cancer transplant patients. While homozygous CCR5-∆32/32 carriers block HIV infection, alternatively they display an increased risk for encephalomyelitis and death when infected with the West Nile virus.

Erratum to: Progress Note 2024: Curing HIV; Not in My Lifetime or Just Around the Corner?

[This corrects the article DOI: 10.20411/pai.v8i2.665.].

Progress Note 2024: Curing HIV; Not in My Lifetime or Just Around the Corner?

Once a death sentence, HIV is now considered a manageable chronic disease due to the development of antiretroviral therapy (ART) regimens with minimal toxicity and a high barrier for genetic resistance. While highly effective in arresting AIDS progression and rendering the virus untransmissible in people living with HIV (PLWH) with undetectable viremia (U=U) [1, 2]), ART alone is incapable of eradicating the "reservoir" of resting, latently infected CD4+ T cells from which virus recrudesces upon treatment cessation. As of 2022 estimates, there are 39 million PLWH, of whom 86% are aware of their status and 76% are receiving ART [3]. As of 2017, ART-treated PLWH exhibit near normalized life expectancies without adjustment for socioeconomic differences [4]. Furthermore, there is a global deceleration in the rate of new infections [3] driven by expanded access to pre-exposure prophylaxis (PrEP), HIV testing in vulnerable populations, and by ART treatment [5]. Therefore, despite outstanding issues pertaining to cost and access in developing countries, there is strong enthusiasm that aggressive testing, treatment, and effective viral suppression may be able to halt the ongoing HIV epidemic (ie, UNAIDS' 95-95-95 targets) [6-8]; especially as evidenced by recent encouraging observations in Sydney [9]. Despite these promising efforts to limit further viral transmission, for PLWH, a "cure" remains elusive; whether it be to completely eradicate the viral reservoir (ie, cure) or to induce long-term viral remission in the absence of ART (ie, control; Figure 1). In a previous salon hosted by Pathogens and Immunity in 2016 [10], some researchers were optimistic that a cure was a feasible, scalable goal, albeit with no clear consensus on the best route. So, how are these cure strategies panning out? In this commentary, 8 years later, we will provide a brief overview on recent advances and failures towards identifying determinants of viral persistence and developing a scalable cure for HIV. Based on these observations, and as in the earlier salon, we have asked several prominent HIV cure researchers for their perspectives.

Safety and Efficacy of Bone Marrow and Adipose Tissue-Derived Mesenchymal Stem Cells for the Treatment of Ischemic Stroke: A Systematic Review

Neurological diseases, including ischemic stroke, are considered a big challenge for public health due to their high prevalence and lack of definitive and effective treatments. Addressing these issues requires innovative therapeutic approaches and among the limited methods available, stem cells have shown promise in improving central nervous system repair by enhancing myelin regeneration and neuronal recovery. To advance this field of research, this systematic review aims to assess the safety and effectiveness of mesenchymal stem cells (MSCs) derived from both bone marrow and adipose tissue for the treatment of ischemic stroke. This study conducted a systematic review in the electronic databases PubMed, Scopus, Web of Science, Embase, ScienceDirect, and Google Scholar to assess the efficacy and safety of MSCs generated from bone marrow and adipose tissue for the treatment of ischemic stroke. It was extracted without a time limit until April 2023. The studies were then transferred to the information management program (EndNote) and duplicates were eliminated. The remaining studies were then examined using the entry and exit criteria and the 3 stages of primary, secondary, and qualitative evaluation, and finally, the results of the final studies were extracted. According to the initial search in the desired databases, 1028 possible related articles were identified and transferred to the information management software (EndNote). After removing 390 duplicate studies, 608 studies were excluded based on inclusion and exclusion criteria. Finally, 37 final studies were included in the systematic review process. Based on the investigations, it was evident that the administration of MSCs derived from both bone marrow and adipose tissue holds significant promise as an effective and safe treatment approach for ischemic stroke. The results consistently showed acceptable outcomes in the studies and this evidence can be recommended for the clinical application of this treatment. Also, the findings of this study report that the use of adipose tissue and bone marrow MSCs in the treatment of ischemic stroke can be used as a practical method.

HIV epidemiology, prevention, treatment, and implementation strategies for public health

The global HIV response has made tremendous progress but is entering a new phase with additional challenges. Scientific innovations have led to multiple safe, effective, and durable options for treatment and prevention, and long-acting formulations for 2-monthly and 6-monthly dosing are becoming available with even longer dosing intervals possible on the horizon. The scientific agenda for HIV cure and remission strategies is moving forward but faces uncertain thresholds for success and acceptability. Nonetheless, innovations in prevention and treatment have often failed to reach large segments of the global population (eg, key and marginalised populations), and these major disparities in access and uptake at multiple levels have caused progress to fall short of their potential to affect public health. Moving forward, sharper epidemiologic tools based on longitudinal, person-centred data are needed to more accurately characterise remaining gaps and guide continued progress against the HIV epidemic. We should also increase prioritisation of strategies that address socio-behavioural challenges and can lead to effective and equitable implementation of existing interventions with high levels of quality that better match individual needs. We review HIV epidemiologic trends; advances in HIV prevention, treatment, and care delivery; and discuss emerging challenges for ending the HIV epidemic over the next decade that are relevant for general practitioners and others involved in HIV care.

HIV-1 infection of genetically engineered iPSC-derived central nervous system-engrafted microglia in a humanized mouse model

IMPORTANCE

Our mouse model is a powerful tool for investigating the genetic mechanisms governing central nervous system (CNS) human immunodeficiency virus type-1 (HIV-1) infection and latency in the CNS at a single-cell level. A major advantage of our model is that it uses induced pluripotent stem cell-derived microglia, which enables human genetics, including gene function and therapeutic gene manipulation, to be explored in vivo, which is more challenging to study with current hematopoietic stem cell-based models for neuroHIV. Our transgenic tracing of xenografted human cells will provide a quantitative medium to develop new molecular and epigenetic strategies for reducing the HIV-1 latent reservoir and to test the impact of therapeutic inflammation-targeting drug interventions on CNS HIV-1 latency.

UK media responses to HIV through the lens of COVID-19: a study of multidirectional memory

This article proposes correlations and parallels in UK newsprint media coverage of the COVID-19 and HIV/AIDS pandemics through engagement with Michael Rothberg's model of multidirectional memory. It achieves this via qualitative and quantitative analysis of newsprint media during selected timelines of the respective outbreaks. Although the COVID-19 outbreak, which originated in Wuhan, China in 2019 and spread globally, has prompted reference to a number of previous traumatic events, including 9/11 and the Holocaust, one might contend that it correlates most closely with HIV/AIDS given the latter's ongoing nature and worldwide reach. COVID-19, having infected 629 million people since December 2019 with 6.5 million deaths by November 2022, still presents a global threat through which we might read the trauma of HIV, a disease that has thus far seen 32.7 million deaths and has infected 75.7 million people worldwide. This relationship exists despite the fact that the two viruses and their effects differ markedly: HIV is a retrovirus, has a long incubation time, is transmitted via bodily fluids, has a low risk of infectivity via everyday contact and, to date, no fully effective vaccine has been developed. Contrastingly, COVID-19 is a coronavirus, has a short incubation time, is transmitted via contact and airborne respiratory aerosols, has a high risk of infectivity via everyday contact, and investment in vaccine development has been significant, with several vaccines now successfully developed. Nonetheless, while the two viruses and their prognoses are quite different and government strategies have followed highly divergent trajectories, certain parallels are apparent to the extent that one might read HIV/AIDS through the lens of COVID-19. It is therefore argued here that the connections between these two traumatic events constitute what Rothberg terms 'multidirectional memory' whereby we understand one traumatic event through another.

Transcriptomic study reveals changes of lncRNAs in PBMCs from HIV-1 patients before and after ART

Long noncoding RNAs (lncRNAs) play important roles in regulating HIV-1 infection and virus-host interactions. However, it is unclear whether and how ART alters lncRNAs in HIV-infected patients. In the present study, we investigated changes of lncRNAs in PBMCs from HIV-1 patients pre- and post-ART. We identified a total of 974 lncRNAs whose expression was restored to normal levels after ART. Cis-acting analysis showed that six lncRNAs have cis-regulated target genes, among which RP11-290F5.1 and interferon regulatory factor 2 (IRF2) were reported to promote HIV replication. Furthermore, we found that lncRNA CTB-119C2.1, which regulates most mRNAs with differential expression in PBMCs from HIV-1 infected patients after ART, was significantly upregulated by RNA-seq and qRT-PCR assays. KEGG analysis of CTB-119C2.1-associated genes revealed that most of the genes are involved in the p53 signaling pathway and pathways related to cell cycle and DNA replication. Our findings thus reveal the dynamic change of lncRNAs in people living with HIV-1 pre- and post-ART and warrant further investigation of the role of lncRNAs in HIV-1 pathogenesis and treatment.

Immune checkpoint inhibitors as potential therapy for reverting T-cell exhaustion and reverting HIV latency in people living with HIV

The immune system of people living with HIV (PLWH) is persistently exposed to antigens leading to systemic inflammation despite combination antiretroviral treatment (cART). This inflammatory milieu promotes T-cell activation and exhaustion. Furthermore, it produces diminished effector functions including loss of cytokine production, cytotoxicity, and proliferation, leading to disease progression. Exhausted T cells show overexpression of immune checkpoint molecules (ICs) on the cell surface, including programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), and lymphocyte activation gene-3 (LAG-3). The ICs also play a crucial role in T-cell exhaustion by reducing the immune response to cancer antigens. Immunotherapy based on immune checkpoint inhibitors (ICIs) has changed the management of a diversity of cancers. Additionally, the interest in exploring this approach in the setting of HIV infection has increased, including AIDS-defining cancers and non-AIDS-defining cancers in PLWH. To date, research on this topic suggests that ICI-based therapies in PLWH could be a safe and effective approach. In this review, we provide an overview of the current literature on the potential role of ICI-based immunotherapy not only in cancer remission in PLWH but also as a therapeutic intervention to restore immune response against HIV, revert HIV latency, and attain a functional cure for HIV infection.

Killing two birds with one stone: CRISPR/Cas9 CCR5 knockout hematopoietic stem cells transplantation to treat patients with HIV infection and hematological malignancies concurrently

Human immunodeficiency virus (HIV) is known to cause hematological malignancy. Hematopoietic stem cell transplantation (HPSCT) is an advanced treatment for that. Currently, there are three successful HIV-eliminated cases, and two received HPSCT from CCR5-absent donors. It is well established that the CCR5 protein on the cell surface assists human immunodeficiency virus entry. Preliminary studies have revealed that knocking out CCR5 and/or CXCR4 may inhibit the viral entry of HIV, which may prove promising in the further development of HIV treatment options. Herein, we suggest performing autologous or allogeneic HSCT with CCR5 KO hematopoietic stem cells in patients who suffer from complicated HIV conditions, particularly drug-resistant HIV or a concurrent diagnosis of HIV with lymphoma/leukemia, to achieve complete HIV remission. Nevertheless, at the clinical forefront of CRISPR-HIV technology, more efforts should be directed to advance nonhuman primate (NHP) models for studies of HIV pathogenesis and off-target assessments within this system. CRISPR-Cas9 knock out of host HSCT-expressing CCR5 or CXCR4 may confer HIV-resistance, which when applied to bedside therapeutics in an allogeneic or autologous manner can warrant a permanent and effective treatment outcome.

Understanding participant perspectives around HIV-1 cure-related studies involving antiretroviral analytical treatment interruptions in the United Kingdom

Background

To test efficacy, HIV cure-related trials often require a period of intensively monitored interruption of antiretroviral therapy (ART) (analytical treatment interruption or ATI). As individuals who started ART during primary HIV-1 infection (PHI) are often recruited, we have asked people already enrolled into an observational PHI study about their willingness and concerns around participating in cure-related studies involving ATIs.

Methods

People who were diagnosed with PHI and started ART, attending two London HIV clinics, provided informed consent to complete a digital survey in clinic between 21/07/21 to October 31, 2023. Questions comprised sociodemographics, motivations, concerns and practical considerations influencing willingness to participate in studies involving ATIs. Hierarchical clustering of responses was performed using the 'pheatmap' R statistical package and ranked from most to least concerned. Responses were cross-referenced with enrolment into an ATI study which recruited from this cohort.

Results

Of 352 eligible participants, 75 completed the survey. The majority were white, cisgender men who have sex with men, 34/75 (45 %) were born outside the UK. 29 (39 %) expressed interest in joining ATI studies. Participants who were interested or unsure in joining ATI studies were primarily motivated (53/65, 82 % very or moderately interested) by an altruistic desire to help scientific research. Across all participants, onward HIV transmission was the predominant concern (67/75, 89 % very or moderately concerned), and similar levels of concerns reported if the HIV-1 viral load threshold to restarting ART was increased from 500 to 50 000 copies/mL. Most participants preferred weekly (23/65, 35 %) or fortnightly (11/65, 17 %) viral load monitoring during an ATI. Before taking part in a study involving an ATI, participants stated they would prefer to discuss this with their HIV doctor (55/65, 85 %).

Conclusion

In this small survey, 39 % of respondents expressed interest in joining studies involving ATIs, primarily for altruistic reasons. Participants were more interested in joining a potential ATI study if a novel intervention was included than simply an ATI alone. The main concern expressed was risk of viral transmission. To inform practical and study design considerations for future ATI studies, unrestricted access for mitigation of transmission risk should be included, and regular, frequent viral load monitoring is preferred.

Genomic Exploration of the Brain in People Infected with HIV-Recent Progress and the Road Ahead

PURPOSE OF REVIEW

The adult human brain harbors billions of microglia and other myeloid and lymphoid cells highly susceptible to HIV infection and retroviral insertion into the nuclear DNA. HIV infection of the brain is important because the brain is a potentially large reservoir site that may be a barrier to HIV cure strategies and because infection can lead to the development of HIV-associated neurocognitive disorder. To better understand both the central nervous system (CNS) reservoir and how it can cause neurologic dysfunction, novel genomic, epigenomic, transcriptomic, and proteomic approaches need to be employed. Several characteristics of the reservoir are important to learn, including where the virus integrates, whether integrated proviruses are intact or defective, whether integrated proviruses can be reactivated from a latent state to seed ongoing infection, and how this all impacts brain function.

RECENT FINDINGS

Here, we discuss similarities and differences of viral integration sites between brain and blood and discuss evidence for and against the hypothesis that in the absence of susceptible T-lymphocytes in the periphery, the virus housing in the infected brain is not able to sustain a systemic infection. Moreover, microglia from HIV + brains across a wide range of disease severity appear to share one type of common alteration, which is defined by downregulated expression, and repressive chromosomal compartmentalization, for microglial genes regulating synaptic connectivity. Therefore, viral infection of the brain, including in immunocompetent cases with near-normal levels of CD4 blood lymphocytes, could be associated with an early disruption in microglia-dependent neuronal support functions, contributing to cognitive and neurological deficits in people living with HIV.

Long-term persistence of transcriptionally active 'defective' HIV-1 proviruses: implications for persistent immune activation during antiretroviral therapy

OBJECTIVES

People with HIV-1 (PWH) on effective antiretroviral therapy (ART) continue to exhibit chronic systemic inflammation, immune activation, and persistent elevations in markers of HIV-1 infection [including HIV-DNA, cell-associated HIV-RNA (CA HIV-RNA), and antibodies to HIV-1 proteins] despite prolonged suppression of plasma HIV-RNA levels less than 50 copies/ml. Here, we investigated the hypothesis that nonreplicating but transcriptionally and translationally competent 'defective' HIV-1 proviruses may be one of drivers of these phenomena.

DESIGN

A combined cohort of 23 viremic and virologically suppressed individuals on ART were studied.

METHODS

HIV-DNA, CA HIV-RNA, western blot score (measure of anti-HIV-1 antibodies as a surrogate for viral protein expression in vivo ), and key biomarkers of inflammation and coagulation (IL-6, hsCRP, TNF-alpha, tissue factor, and D-dimer) were measured in peripheral blood and analyzed using a combined cross-sectional and longitudinal approaches. Sequences of HIV-DNA and CA HIV-RNA obtained via 5'-LTR-to-3'-LTR PCR and single-genome sequencing were also analyzed.

RESULTS

We observed similar long-term persistence of multiple, unique, transcriptionally active 'defective' HIV-1 provirus clones (average: 11 years., range: 4-20 years) and antibody responses against HIV-1 viral proteins among all ART-treated participants evaluated. A direct correlation was observed between the magnitude of HIV-1 western blot score and the levels of transcription of 'defective' HIV-1 proviruses ( r  = 0.73, P  < 0.01). Additional correlations were noted between total CD8 + T-cell counts and HIV-DNA ( r  = 0.52, P  = 0.01) or CA HIV-RNA ( r  = 0.65, P  < 0.01).

CONCLUSION

These findings suggest a novel interplay between transcription and translation of 'defective' HIV-1 proviruses and the persistent immune activation seen in the setting of treated chronic HIV-1 infection.

The latent HIV reservoir: current advances in genetic sequencing approaches

Multiple cellular HIV reservoirs in diverse anatomical sites can undergo clonal expansion and persist for years despite suppressive antiretroviral therapy, posing a major barrier toward an HIV cure. Commonly adopted assays to assess HIV reservoir size mainly consist of PCR-based measures of cell-associated total proviral DNA, intact proviruses and transcriptionally competent provirus (viral RNA), flow cytometry and microscopy-based methods to measure translationally competent provirus (viral protein), and quantitative viral outgrowth assay, the gold standard to measure replication-competent provirus; yet no assay alone can provide a comprehensive view of the total HIV reservoir or its dynamics. Furthermore, the detection of extant provirus by these measures does not preclude defects affecting replication competence. An accurate measure of the latent reservoir is essential for evaluating the efficacy of HIV cure strategies. Recent approaches have been developed, which generate proviral sequence data to create a more detailed profile of the latent reservoir. These sequencing approaches are valuable tools to understand the complex multicellular processes in a diverse range of tissues and cell types and have provided insights into the mechanisms of HIV establishment and persistence. These advancements over previous sequencing methods have allowed multiplexing and new assays have emerged, which can document transcriptional activity, chromosome accessibility, and in-depth cellular phenotypes harboring latent HIV, enabling the characterization of rare infected cells across restrictive sites such as the brain. In this manuscript, we provide a review of HIV sequencing-based assays adopted to address challenges in quantifying and characterizing the latent HIV reservoir.

Exploiting a rodent cell block for intrinsic resistance to HIV-1 gene expression in human T cells

IMPORTANCE

Unlike humans, mice are unable to support HIV-1 infection. This is due, in part, to a constellation of defined minor, species-specific differences in conserved host proteins needed for viral gene expression. Here, we used precision CRISPR/Cas9 gene editing to engineer a "mousified" version of one such host protein, cyclin T1 (CCNT1), in human T cells. CCNT1 is essential for efficient HIV-1 transcription, making it an intriguing target for gene-based inactivation of virus replication. We show that isogenic cell lines engineered to encode CCNT1 bearing a single mouse-informed amino acid change (tyrosine in place of cysteine at position 261) exhibit potent, durable, and broad-spectrum resistance to HIV-1 and other pathogenic lentiviruses, and with no discernible impact on host cell biology. These results provide proof of concept for targeting CCNT1 in the context of one or more functional HIV-1 cure strategies.

Identifying physiological tissue niches that support the HIV reservoir in T cells

Successful antiretroviral therapy (ART) can efficiently suppress Human Immunodeficiency Virus-1 (HIV-1) replication to undetectable levels, but rare populations of infected memory CD4+ T cells continue to persist, complicating viral eradication efforts. Memory T cells utilize distinct homing and adhesion molecules to enter, exit, or establish residence at diverse tissue sites, integrating cellular and environmental cues that maintain homeostasis and life-long protection against pathogens. Critical roles for T cell receptor and cytokine signals driving clonal expansion and memory generation during immunity generation are well established, but whether HIV-infected T cells can utilize similar mechanisms for their own long-term survival is unclear. How infected, but transcriptionally silent T cells maintain their recirculation potential through blood and peripheral tissues, or whether they acquire new capabilities to establish unique peripheral tissue niches, is also not well understood. In this review, we will discuss the cellular and molecular cues that are important for memory T cell homeostasis and highlight opportunities for HIV to hijack normal immunological processes to establish long-term viral persistence.

Characterisation of HIV-1 reservoirs in paediatric populations: protocol for a systematic review and meta-analysis

INTRODUCTION

The success of antiretroviral therapy (ART) has changed HIV from a deadly to a chronic infection, thus increasing the transitioning from infancy toward adulthood. However, the virostatic nature of antiretrovirals maintains viruses in sanctuaries, with reactivation potentials. Because current ARTs are very limited for children, the emergence of new HIV epidemics driven by HIV drug-resistance mutations is favoured. Our systematic review aims to estimate the global burden of archived drug-resistance mutations (ADRMs) and the size of reservoir (HIV-1 DNA load), and their associated factors in children and adolescents.

METHODS AND ANALYSIS

Papers from the PubMed/MEDLINE, Google Scholar, ScienceDirect, African Journals Online and Academic Medical Education Databases will be systematically identified using the keywords: "HIV-1 reservoirs", "viral reservoirs", "HIV-1 DNA", infants, adolescents, child and children, linked by the following Boolean operators: 'OR' and 'AND'. Randomised and non-randomised trials, cohort studies and cross-sectional studies published in French or English from January 2002 will be included, while case reports, letters, comments, reviews, systematic reviews and meta-analyses, and editorials will be excluded. All studies describing data on ADRMs, HIV-1 DNA load and/or immunological markers among children/adolescents will be eligible. A random-effects model will be used to calculate the pooled prevalence of ADRMs. Data will be reported according to type of viral reservoir (peripheral blood mononuclear cells, CD4 cells), geographical location (country/continent), ethnicity/race, age (infants vs adolescents), gender, HIV-1 clades, ART exposure (naïve vs treated, drug class, type of regimen, age at ART initiation and treatment duration), WHO clinical staging (I, II, III, IV), immune status (immune compromised vs immune competent) and virological response (viraemic vs non-viraemic). Multivariate logistic regression will be performed to determine predictors of HIV reservoir profile in paediatric populations. The primary outcome will be to assess the genotypical and quantitative profile of HIV reservoirs, while the secondary outcomes will be to identify factors associated with ADRMs and reservoir size in paediatric populations.

ETHICS AND DISSEMINATION

Ethical approval is not applicable for this study as it will be based on published data. Results will be disseminated via a peer-reviewed scientific journal and relevant conferences.

PROSPERO REGISTRATION NUMBER

CRD42022327625.

A partner protection package for HIV cure-related trials involving analytical treatment interruptions

Analytical treatment interruptions (ATIs) have become a key methodological approach to evaluate the effects of experimental HIV cure-related research interventions. During ATIs, sex partners of trial participants might be at risk of acquiring HIV. This risk raises both ethical and feasibility concerns about ATI trials. We propose a partner protection package (P3) approach to address these concerns. A P3 approach would provide guidance to investigators, sponsors, and those who are designing and implementing context-specific partner protections in HIV cure-related trials involving ATIs. The approach would also help assure institutional review boards, trial participants, and communities that ATI trials with a P3 would provide appropriate partner protections. We offer a prototype P3 framework that delineates three basic considerations for protecting participants' sex partners during ATI trials: (1) ensuring the scientific and social value of the ATI and the trial, (2) reducing the likelihood of unintended HIV transmission, and (3) ensuring prompt management of any acquired HIV infection. We outline possible ways of implementing these basic considerations.

Modulation of HIV-1 capsid multimerization by sennoside A and sennoside B via interaction with the NTD/CTD interface in capsid hexamer

Small molecules that bind to the pocket targeted by a peptide, termed capsid assembly inhibitor (CAI), have shown antiviral effects with unique mechanisms of action. We report the discovery of two natural compounds, sennoside A (SA) and sennoside B (SB), derived from medicinal plants that bind to this pocket in the C-terminal domain of capsid (CA CTD). Both SA and SB were identified via a drug-screening campaign that utilized a time-resolved fluorescence resonance energy transfer assay. They inhibited the HIV-1 CA CTD/CAI interaction at sub-micromolar concentrations of 0.18 μM and 0.08 μM, respectively. Mutation of key residues (including Tyr 169, Leu 211, Asn 183, and Glu 187) in the CA CTD decreased their binding affinity to the CA monomer, from 1.35-fold to 4.17-fold. Furthermore, both compounds induced CA assembly in vitro and bound directly to the CA hexamer, suggesting that they interact with CA beyond the CA CTD. Molecular docking showed that both compounds were bound to the N-terminal domain (NTD)/CTD interface between adjacent protomers within the CA hexamer. SA established a hydrogen-bonding network with residues N57, V59, Q63, K70, and N74 of CA1-NTD and Q179 of CA2-CTD. SB formed hydrogen bonds with the N53, N70, and N74 residues of CA1-NTD, and the A177and Q179 residues of CA2-CTD. Both compounds, acting as glue, can bring αH4 in the NTD and αH9 in the CTD of the NTD/CTD interface close to each other. Collectively, our research indicates that SA and SB, which enhance CA assembly, could serve as novel chemical tools to identify agents that modulate HIV-1 CA assembly. These natural compounds may potentially lead to the development of new antiviral therapies with unique mechanisms of action.

Advances in long-acting slow effective release antiretroviral therapies for treatment and prevention of HIV infection

Adherence to daily oral antiretroviral therapy (ART) is a barrier to both treatment and prevention of human immunodeficiency virus (HIV) infection. To overcome limitations of life-long daily regimen adherence, long-acting (LA) injectable antiretroviral (ARV) drugs, nanoformulations, implants, vaginal rings, microarray patches, and ultra-long-acting (ULA) prodrugs are now available or in development. These medicines enable persons who are or at risk for HIV infection to be treated with simplified ART regimens. First-generation LA cabotegravir, rilpivirine, and lenacapavir injectables and a dapivirine vaginal ring are now in use. However, each remains limited by existing dosing intervals, ease of administration, or difficulties in finding drug partners. ULA ART regimens provide an answer, but to date, such next-generation formulations remain in development. Establishing the niche will require affirmation of extended dosing, improved access, reduced injection volumes, improved pharmacokinetic profiles, selections of combination treatments, and synchronization of healthcare support. Based on such needs, this review highlights recent pharmacological advances and a future treatment perspective. While first-generation LA ARTs are available for HIV care, they remain far from ideal in meeting patient needs. ULA medicines, now in advanced preclinical development, may close gaps toward broader usage and treatment options.

Strategies for enhancing CAR T cell expansion and persistence in HIV infection

Chimeric Antigen Receptor (CAR) T cell therapies are tremendously successful in hematological malignancies and show great promise as treatment and curative strategy for HIV. A major determinant for effective CAR T cell therapy is the persistence of CAR T cells. Particularly, antigen density and target cell abundance are crucial for the engagement, engraftment, and persistence of CAR T cells. The success of HIV-specific CAR T cells is challenged by limited antigen due to low cell surface expression of viral proteins and the scarcity of chronically infected cells during antiretroviral therapy. Several strategies have been explored to increase the efficacy of CAR T cells by enhancing expansion and persistence of the engineered cells. This review highlights the challenges of designing CAR T cells against HIV and other chronic viral infections. We also discuss potential strategies to enhance CAR T cell expansion and persistence in the setting of low antigen exposure.

Molecular mechanisms by which the HIV-1 latent reservoir is established and therapeutic strategies for its elimination

The human immunodeficiency virus type 1 (HIV-1) reservoir, composed of cells harboring the latent, integrated virus, is not eliminated by antiretroviral therapy. It therefore represents a significant barrier to curing the infection. The biology of HIV-1 reservoirs, the mechanisms of their persistence, and effective strategies for their eradication are not entirely understood. Here, we review the molecular mechanisms by which HIV-1 reservoirs develop, the cells and compartments where the latent virus resides, and advancements in curative therapeutic strategies. We first introduce statistics and relevant data on HIV-1 infection, aspects of pathogenesis, the role of antiretroviral therapy, and the general features of the latent HIV reservoir. Then, the article is built on three main pillars: The molecular mechanisms related to latency, the different strategies for targeting the reservoir to obtain a cure, and the current progress in immunotherapy to counteract said reservoirs.

Allogeneic immunity clears latent virus following allogeneic stem cell transplantation in SIV-infected ART-suppressed macaques

Allogeneic hematopoietic stem cell transplantation (alloHSCT) from donors lacking C-C chemokine receptor 5 (CCR5Δ32/Δ32) can cure HIV, yet mechanisms remain speculative. To define how alloHSCT mediates HIV cure, we performed MHC-matched alloHSCT in SIV+, anti-retroviral therapy (ART)-suppressed Mauritian cynomolgus macaques (MCMs) and demonstrated that allogeneic immunity was the major driver of reservoir clearance, occurring first in peripheral blood, then peripheral lymph nodes, and finally in mesenteric lymph nodes draining the gastrointestinal tract. While allogeneic immunity could extirpate the latent viral reservoir and did so in two alloHSCT-recipient MCMs that remained aviremic >2.5 years after stopping ART, in other cases, it was insufficient without protection of engrafting cells afforded by CCR5-deficiency, as CCR5-tropic virus spread to donor CD4+ T cells despite full ART suppression. These data demonstrate the individual contributions of allogeneic immunity and CCR5 deficiency to HIV cure and support defining targets of alloimmunity for curative strategies independent of HSCT.

Targeting and eradicating latent CNS reservoirs of HIV-1: original strategies and new models

Nowadays, combination antiretroviral therapy (cART) is the standard treatment for all people with human immunodeficiency virus (HIV-1). Although cART is effective in treating productive infection, it does not eliminate latent reservoirs of the virus. This leads to lifelong treatment associated with the occurrence of side effects and the development of drug-resistant HIV-1. Suppression of viral latency is therefore the major hurdle to HIV-1 eradication. Multiple mechanisms exist to regulate viral gene expression and drive the transcriptional and post-transcriptional establishment of latency. Epigenetic processes are amongst the most studied mechanisms influencing both productive and latent infection states. The central nervous system (CNS) represents a key anatomical sanctuary for HIV and is the focal point of considerable research efforts. However, limited and difficult access to CNS compartments makes understanding the HIV-1 infection state in latent brain cells such as microglial cells, astrocytes, and perivascular macrophages challenging. This review examines the latest advances on epigenetic transformations involved in CNS viral latency and targeting of brain reservoirs. Evidence from clinical studies as well as in vivo and in vitro models of HIV-1 persistence in the CNS will be discussed, with a special focus on recent 3D in vitro models such as human brain organoids. Finally, the review will address therapeutic considerations for targeting latent CNS reservoirs.

HIV Tissue Reservoirs: Current Advances in Research

Acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV), has become a heavy burden of disease and an important public health problem in the world. Although current antiretroviral therapy (ART) is effective at suppressing the virus in the blood, HIV still remains in two different types of reservoirs-the latently infected cells (represented by CD4⁺ T cells) and the tissues containing those cells, which may block access to ART, HIV-neutralizing antibodies and latency-reversing agents. The latter is the focus of our review, as blood viral load drops below detectable levels after ART, a deeper and more systematic understanding of the HIV tissue reservoirs is imperative. In this review, we take the lymphoid system (including lymph nodes, gut-associated lymphoid tissue, spleen and bone marrow), nervous system, respiratory system, reproductive system (divided into male and female), urinary system as the order, focusing on the particularity and importance of each tissue in HIV infection, the infection target cell types of each tissue, the specific infection situation of each tissue quantified by HIV DNA or HIV RNA and the evidence of compartmentalization and pharmacokinetics. In summary, we found that the present state of HIV in different tissues has both similarities and differences. In the future, the therapeutic principle we need to follow is to respect the discrepancy on the basis of grasping the commonality. The measures taken to completely eliminate the virus in the whole body cannot be generalized. It is necessary to formulate personalized treatment strategies according to the different characteristics of the HIV in the various tissues, so as to realize the prospect of curing AIDS as soon as possible.

Genetic Variants within SARS-CoV-2 Human Receptor Genes May Contribute to Variable Disease Outcomes in Different Ethnicities

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into a global pandemic, with an alarming infectivity and mortality rate. Studies have examined genetic effects on SARS-CoV-2 disease susceptibility and severity within Eurasian populations. These studies identified contrasting effects on the severity of disease between African populations. Genetic factors can explain some of the diversity observed within SARS-CoV-2 disease susceptibility and severity. Single nucleotide polymorphisms (SNPs) within the SARS-CoV-2 receptor genes have demonstrated detrimental and protective effects across ethnic groups. For example, the TT genotype of rs2285666 (Angiotensin-converting enzyme 2 (ACE2)) is associated with the severity of SARS-CoV-2 disease, which is found at higher frequency within Asian individuals compared to African and European individuals. In this study, we examined four SARS-CoV-2 receptors, ACE2, Transmembrane serine protease 2 (TMPRSS2), Neuropilin-1 (NRP1), and Basigin (CD147). A total of 42 SNPs located within the four receptors were reviewed: ACE2 (12), TMPRSS2 (10), BSG (CD147) (5), and NRP1 (15). These SNPs may be determining factors for the decreased disease severity observed within African individuals. Furthermore, we highlight the absence of genetic studies within the African population and emphasize the importance of further research. This review provides a comprehensive summary of specific variants within the SARS-CoV-2 receptor genes, which can offer a better understanding of the pathology of the SARS-CoV-2 pandemic and identify novel potential therapeutic targets.

Challenges in HIV-1 Latent Reservoir and Target Cell Quantification in CAR-T Cell and Other Lentiviral Gene Modifying HIV Cure Strategies

Gene-modification therapies are at the forefront of HIV-1 cure strategies. Chimeric antigen receptor (CAR)-T cells pose a potential approach to target infected cells during antiretroviral therapy or following analytical treatment interruption (ATI). However, there are technical challenges in the quantification of HIV-1-infected and CAR-T cells in the setting of lentiviral CAR gene delivery and also in the identification of cells expressing target antigens. First, there is a lack of validated techniques to identify and characterize cells expressing the hypervariable HIV gp120 in both ART-suppressed and viremic individuals. Second, close sequence homology between lentiviral-based CAR-T gene modification vectors and conserved regions of HIV-1 creates quantification challenges of HIV-1 and lentiviral vector levels. Consideration needs to be taken into standardizing HIV-1 DNA/RNA assays in the setting of CAR-T cell and other lentiviral vector-based therapies to avoid these confounding interactions. Lastly, with the introduction of HIV-1 resistance genes in CAR-T cells, there is a need for assays with single-cell resolution to determine the competence of the gene inserts to prevent CAR-T cells from becoming infected in vivo. As novel therapies continue to arise in the HIV-1 cure field, resolving these challenges in CAR-T-cell therapy will be crucial.

HIV-1 infection of genetically engineered iPSC-derived central nervous system-engrafted microglia in a humanized mouse model

The central nervous system (CNS) is a major human immunodeficiency virus type 1 reservoir. Microglia are the primary target cell of HIV-1 infection in the CNS. Current models have not allowed the precise molecular pathways of acute and chronic CNS microglial infection to be tested with in vivo genetic methods. Here, we describe a novel humanized mouse model utilizing human-induced pluripotent stem cell-derived microglia to xenograft into murine hosts. These mice are additionally engrafted with human peripheral blood mononuclear cells that served as a medium to establish a peripheral infection that then spread to the CNS microglia xenograft, modeling a trans-blood-brain barrier route of acute CNS HIV-1 infection with human target cells. The approach is compatible with iPSC genetic engineering, including inserting targeted transgenic reporter cassettes to track the xenografted human cells, enabling the testing of novel treatment and viral tracking strategies in a comparatively simple and cost-effective way vivo model for neuroHIV.

HIV-1 remission and possible cure in a woman after haplo-cord blood transplant

Previously, two men were cured of HIV-1 through CCR5Δ32 homozygous (CCR5Δ32/Δ32) allogeneic adult stem cell transplant. We report the first remission and possible HIV-1 cure in a mixed-race woman who received a CCR5Δ32/Δ32 haplo-cord transplant (cord blood cells combined with haploidentical stem cells from an adult) to treat acute myeloid leukemia (AML). Peripheral blood chimerism was 100% CCR5Δ32/Δ32 cord blood by week 14 post-transplant and persisted through 4.8 years of follow-up. Immune reconstitution was associated with (1) loss of detectable replication-competent HIV-1 reservoirs, (2) loss of HIV-1-specific immune responses, (3) in vitro resistance to X4 and R5 laboratory variants, including pre-transplant autologous latent reservoir isolates, and (4) 18 months of HIV-1 control with aviremia, off antiretroviral therapy, starting at 37 months post-transplant. CCR5Δ32/Δ32 haplo-cord transplant achieved remission and a possible HIV-1 cure for a person of diverse ancestry, living with HIV-1, who required a stem cell transplant for acute leukemia.

Walk on the wild side: SIV infection in African non-human primate hosts-from the field to the laboratory

HIV emerged following cross-species transmissions of simian immunodeficiency viruses (SIVs) that naturally infect non-human primates (NHPs) from Africa. While HIV replication and CD4+ T-cell depletion lead to increased gut permeability, microbial translocation, chronic immune activation, and systemic inflammation, the natural hosts of SIVs generally avoid these deleterious consequences when infected with their species-specific SIVs and do not progress to AIDS despite persistent lifelong high viremia due to long-term coevolution with their SIV pathogens. The benign course of natural SIV infection in the natural hosts is in stark contrast to the experimental SIV infection of Asian macaques, which progresses to simian AIDS. The mechanisms of non-pathogenic SIV infections are studied mainly in African green monkeys, sooty mangabeys, and mandrills, while progressing SIV infection is experimentally modeled in macaques: rhesus macaques, pigtailed macaques, and cynomolgus macaques. Here, we focus on the distinctive features of SIV infection in natural hosts, particularly (1): the superior healing properties of the intestinal mucosa, which enable them to maintain the integrity of the gut barrier and prevent microbial translocation, thus avoiding excessive/pathologic immune activation and inflammation usually perpetrated by the leaking of the microbial products into the circulation; (2) the gut microbiome, the disruption of which is an important factor in some inflammatory diseases, yet not completely understood in the course of lentiviral infection; (3) cell population shifts resulting in target cell restriction (downregulation of CD4 or CCR5 surface molecules that bind to SIV), control of viral replication in the lymph nodes (expansion of natural killer cells), and anti-inflammatory effects in the gut (NKG2a/c+ CD8+ T cells); and (4) the genes and biological pathways that can shape genetic adaptations to viral pathogens and are associated with the non-pathogenic outcome of the natural SIV infection. Deciphering the protective mechanisms against SIV disease progression to immunodeficiency, which have been established through long-term coevolution between the natural hosts and their species-specific SIVs, may prompt the development of novel therapeutic interventions, such as drugs that can control gut inflammation, enhance gut healing capacities, or modulate the gut microbiome. These developments can go beyond HIV infection and open up large avenues for correcting gut damage, which is common in many diseases.

Role of TLRs in HIV-1 Infection and Potential of TLR Agonists in HIV-1 Vaccine Development and Treatment Strategies

Toll-like receptors (TLRs), as a family of pattern recognition receptors, play an important role in the recognition of HIV-1 molecular structures by various cells of the innate immune system, but also provide a functional association with subsequent mechanisms of adaptive immunity. TLR7 and TLR8 play a particularly important role in the innate immune response to RNA viruses due to their ability to recognise GU-rich single-stranded RNA molecules and subsequently activate intracellular signalling pathways resulting in expression of genes coding for various biological response modifiers (interferons, proinflammatory cytokines, chemokines). The aim of this review is to summarise the most recent knowledge on the role of TLRs in the innate immune response to HIV-1 and the role of TLR gene polymorphisms in the biology and in the clinical aspects of HIV infections. In addition, the role of TLR agonists as latency reversing agents in research to treat HIV infections and as immunomodulators in HIV vaccine research will be discussed.

CAS12e (CASX2) CLEAVAGE OF CCR5: IMPACT OF GUIDE RNA LENGTH AND PAM SEQUENCE ON CLEAVAGE ACTIVITY

CRISPR/Cas is under development as a therapeutic tool for the cleavage, excision, and/or modification of genes in eukaryotic cells. While much effort has focused on CRISPR/Cas from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9), alternative CRISPR systems have been identified using metagenomic datasets from non-pathogenic microbes, including previously unknown class 2 systems, adding to a diverse toolbox of gene editors. The Cas12e (CasX1, CasX2) endonucleases from non-pathogenic Deltaproteobacteria (DpeCas12e) and Planctomycetes (PlmCas12e) are more compact than SpCas9, have a more selective protospacer adjacent motif (PAM) requirement, and deliver a staggered cleavage cut with 5-7 base overhangs. We investigated varying guide RNA (spacer) lengths and alternative PAM sequences to determine optimal conditions for PlmCas12e cleavage of the cellular gene CCR5 (CC-Chemokine receptor-5). CCR5 encodes one of two chemokine coreceptors required by HIV-1 to infect target cells, and a mutation of CCR5 (delta-32) is responsible for HIV-1 resistance and reported cures following bone marrow transplantation. Consequently, CCR5 has been an important target for gene editing utilizing CRISPR, TALENs, and ZFNs. We determined that CCR5 cleavage activity varied with the target site, guide RNA length, and the terminal nucleotide in the PAM sequence. Our analyses demonstrated a PlmCas12e PAM preference for purines (A, G) over pyrimidines (T, C) in the fourth position of the CasX2 PAM (TTCN). These analyses have contributed to a better understanding of CasX2 cleavage requirements and will position us more favorably to develop a therapeutic that creates the delta-32 mutation in the CCR5 gene in hematopoietic stem cells.