Barriers for HIV Cure: The Latent Reservoir

Enhanced HIV immune responses elicited by an apoptotic single-cycle SHIV lentivector DNA vaccine

Background

HIV remains a major public health issue in spite of antiretroviral therapy (ART). An innovative vaccine that can induce long-lasting and effective immunity is required to curb the persistently high numbers of new infections worldwide.

Methods

A novel DNA vaccine was generated using a Simian-Human Immunodeficiency Virus (SHIV) backbone with a Zambian T/F clade C envelope and under the control of the caprine arthritis encephalitis virus long terminal repeats (LTRs) for constitutive expression. Due to the deleted integrase, this DNA vaccine "CSH-DIN-T/F Z331" performs only a single replication cycle. To increase immunogenicity, the co-expression of apoptotic genes (BAX, BAK, or caspase 8) incorporated at the end of Pol was tested to promote the release of apoptotic bodies taken up by dendritic cells leading to cross-presentation of antigen. The three vaccines (CSH-DIN-T/F Z331-BAX, CSH-DIN-T/F Z331-BAK, and CSH-DIN-T/F Z331-Cas8) were tested in vitro for expression and in vivo in BALB/cJ mice for immunogenicity.

Results

Transduced HEK293 cells co-cultured with CEMx174 confirmed the single replication cycle of the DNA vaccine and the induction of apoptosis by CSH-DIN-T/F Z331-Cas8 based on Annexin V expression. BALB/cJ mice were immunized with a combined intramuscular + intradermal/electroporation approach. Intracellular cytokine staining (ICS) from splenocytes collected 12 weeks post-prime/6 weeks post-boost demonstrated a clear superiority of caspase 8 expressing construct over the others, with higher proportions of IFN-γ-, IL-2-, and IL-21-producing CD8 T cells specific to Env, Gag, and Nef. The kinetics of immune response after various immunization schedules were also investigated.

Conclusion

This novel single-cycle DNA vaccine with apoptotic genes demonstrated an enhanced immunogenicity primarily for antigen-specific CD8+ T-cell responses.

Harnessing antiviral RNAi therapeutics for pandemic viruses: SARS-CoV-2 and HIV

Using the knowledge from decades of research into RNA-based therapies, the COVID-19 pandemic response saw the rapid design, testing and production of the first ever mRNA vaccines approved for human use in the clinic. This breakthrough has been a significant milestone for RNA therapeutics and vaccines, driving an exponential growth of research into the field. The development of novel RNA therapeutics targeting high-threat pathogens, that pose a substantial risk to global health, could transform the future of health delivery. In this review, we provide a detailed overview of the two RNA interference (RNAi) pathways and how antiviral RNAi therapies can be used to treat acute or chronic diseases caused by the pandemic viruses SARS-CoV-2 and HIV, respectively. We also provide insights into short-interfering RNA (siRNA) delivery systems, with a focus on how lipid nanoparticles can be functionalized to achieve targeted delivery to specific sites of disease. This review will provide the current developments of SARS-CoV-2 and HIV targeted siRNAs, highlighting strategies to advance the progression of antiviral siRNA along the clinical development pathway.

Host RNA-Binding Proteins as Regulators of HIV-1 Replication

RNA-binding proteins (RBPs) are cellular factors involved in every step of RNA metabolism. During HIV-1 infection, these proteins are key players in the fine-tuning of viral and host cellular and molecular pathways, including (but not limited to) viral entry, transcription, splicing, RNA modification, translation, decay, assembly, and packaging, as well as the modulation of the antiviral response. Targeted studies have been of paramount importance in identifying and understanding the role of RNA-binding proteins that bind to HIV-1 RNAs. However, novel approaches aimed at identifying all the proteins bound to specific RNAs (RBPome), such as RNA interactome capture, have also contributed to expanding our understanding of the HIV-1 replication cycle, allowing the identification of RBPs with functions not only in viral RNA metabolism but also in cellular metabolism. Strikingly, several of the RBPs found through interactome capture are not canonical RBPs, meaning that they do not have conventional RNA-binding domains and are therefore not readily predicted as being RBPs. Further studies on the different cellular targets of HIV-1, such as subtypes of T cells or myeloid cells, or on the context (active replication versus reactivation from latency) are needed to fully elucidate the host RBPome bound to the viral RNA, which will allow researchers and clinicians to discover new therapeutic targets during active replication and provirus reactivation from latency.

Efficacy and Possible Mechanism(s) of Action of Gallium Tetraphenylporphyrin Nanoparticles against HIV-TB Coinfection in an In Vitro Granuloma Structure Model

Coinfection of Mycobacterium tuberculosis (Mtb) and human immunodeficiency virus-1 (HIV) is a significant public health concern. Treatment is challenging due to prolonged duration of therapy and drug interactions between antiretroviral therapy (ART) and anti-TB drugs. Noniron gallium meso-tetraphenyl porphyrin (GaTP), a heme mimetic, has shown broad antimicrobial activity. Here, we investigated the efficacy of nanoparticle encapsulating GaTP (GaNP) for the treatment of HIV and Mtb coinfection or single infection in in vitro granuloma structures. GaNP significantly reduced viable Mtb within primary human in vitro granuloma structures infected with Mtb H37Rv-lux and significantly reduced levels of HIV in CD4+ T cells infected with the virus axenically. Similarly, GaNP exhibited significant antimicrobial activity against HIV/Mtb-coinfected granuloma structures created in vitro, which contain the primary immune cells seen in human TB granulomas, including CD4+ T cells and macrophages, as assessed by a luciferase assay for Mtb and p24 ELISA for HIV detection. Furthermore, mechanistic studies revealed that GaTP increases the level of reactive oxygen species and inhibits catalase in Mtb. A significant increase in Mtb nitrate reductase activity was also observed when Mtb was incubated with GaTP and sodium nitrate. Overall, increased oxidative stress and nitrite levels induced by GaTP are consistent with the possibility that GaTP inhibits Mtb aerobic respiration, which leads to incomplete O2 reduction and a shift to respiration using exogenous NO3. These cumulative data continue to support the potential for developing the noniron heme analog GaTP and its nanoparticle GaNP as new therapeutic approaches for the treatment of HIV/Mtb coinfection.

Disruption of LEDGF/p75-directed integration derepresses antisense transcription of the HIV-1 genome

Disruption of HIV-1 Integrase (IN) interactions with the host-factor Lens Epithelium-Derived Growth Factor (LEDGF)/p75 leads to decreased, random integration, increased latent infection, and described here, accumulation of HIV-1 antisense RNA (asRNA). asRNA increase was observed following interruptions of IN-LEDGF/p75 interactions either through pharmacologic perturbations of IN-LEDGF/p75 by treatment with allosteric HIV-1 integrase inhibitors (ALLINIs) or in cell lines with LEDGF genetic knockout. Additionally, by impairing Tat-dependent HIV transcription, asRNA abundance markedly increases. Illumina sequencing characterization of asRNA transcripts in primary T cells infected in the presence of ALLINIs showed that most initiate from within the HIV-1. Overall, loss of IN-LEDGF/p75 interactions increase asRNA abundance. Understanding the relationship between ALLINIs, integration sites, asRNA, and latency could aid in future therapeutic strategies.

Development of a latency model for HIV-1 subtype C and the impact of long terminal repeat element genetic variation on latency reversal

Sub-Saharan Africa accounts for almost 70 % of people living with HIV (PLWH) worldwide, with the greatest numbers centred in South Africa where 98 % of infections are caused by subtype C (HIV-1C). However, HIV-1 subtype B (HIV-1B), prevalent in Europe and North America, has been the focus of most cure research and testing despite making up only 12 % of HIV-1 infections globally. Development of latency models for non-subtype B viruses is a necessary step to address this disproportionate focus. Furthermore, the impact of genetic variation between viral subtypes, specifically within the long terminal repeat (LTR) element of the viral transcriptional promoter on latency reversal, remains unclear. To address this scientific gap, we constructed a minimal genome retroviral vector expressing HIV-1C consensus transactivator of transcription protein (Tat) and green fluorescent protein (GFP) under the control of either HIV-1C consensus LTR (C731CC) or the transmitted/founder (T/F) LTRs derived from PLWH (CT/F731CC), produced corresponding LTR pseudotyped viruses using a vesicular stomatitis virus (VSV-G) pseudotyped Envelope vector and the pCMVΔR8.91 packaging vector containing HIV-1 accessory and rev genes. Viruses produced in this way were used to infect Jurkat E6 and primary CD4+ T cells in vitro. By enriching for latently infected cells, and treating them with different latency reversing agents, we developed an HIV-1C latency model that demonstrated that the HIV-1C consensus LTR has lower reactivation potential compared to its HIV-1B counterpart. Furthermore, HIV-1C T/F LTR pseudotyped proviral genetic variants exhibited a heterogenous reactivation response which was modulated by host cell (genetic) variation. Our data suggests that genetic variation both within and between HIV-1 subtypes influences latency reversal. Future studies should investigate the specific role of variation in host cellular environment on reactivation differences.

Defective proviruses significantly impact viral transcription and immune activation in men and women with HIV-1 subtype C in rural South Africa

Introduction

The main obstacle to achieving an HIV-1 cure is the proviral reservoir. To promote equity in HIV cure strategies, it is crucial to study the viral reservoir of the predominant HIV-1 subtype C in both women and men. Therefore, we investigated the dynamics of the (intact) viral reservoir in relation to plasma viral load (VL), CD4+ T cell count, and immune activation before and during 96 weeks of successful antiretroviral therapy (ART).

Methods

Eighty-two participants (62% female) newly initiating ART in a rural clinic in South Africa were included in the study. Blood samples were collected at baseline, week 48, and week 96, and CD4 count was determined. Plasma was used for VL and immune marker analyses, while isolated peripheral blood mononuclear cells (PBMCs) were used for the quantification of cellular multiple spliced HIV-1 RNA (msRNA) and the intact proviral DNA assay. For the longitudinal analyses on ART, we selected only those participants who durably suppressed their VL to <200 copies/mL during 48 (n=65) and/or 96 (n=60) weeks of treatment.

Results

At ART initiation, the median CD4 count was 234 cells/mm3 and VL was 68,897 copies/mL. Interestingly, at baseline the number of defective proviruses was significantly correlated with VL (p<0.0001), msRNA (p<0.0001), CD4 count (p=0.0008), CXCL10 (p=0.0003) and TNF-α (p=0.0394). During successful ART, a significant decrease of both the intact and defective proviral reservoir was observed (p<0.0001). The decrease of the intact proviral reservoir was more profound compared to the defective fraction after 96 weeks of therapy. In addition, a significant decrease in cellular msRNA and IL-6, IL-7, TNF-α, sCD14, sCD163, CCL2, CXCL10, and CRP was detected.

Discussion

This study underscores the significant relationship observed prior to therapy initiation between the number of defective proviruses, viral transcription/production and their association with immune response indicators such as CD4 count, CXCL10, and TNF-α. Furthermore, the observation of a less pronounced decrease of the defective proviral DNA highlights the importance of addressing both intact and defective proviruses in therapeutic strategies to enhance clinical outcomes for people with HIV-1. Together, these findings suggest a significant role of the defective proviruses in HIV-related disease progression.

A new class of capsid-targeting inhibitors that specifically block HIV-1 nuclear import

HIV-1 capsids cross nuclear pore complexes (NPCs) by engaging with the nuclear import machinery. To identify compounds that inhibit HIV-1 nuclear import, we screened drugs in silico on a three-dimensional model of a CA hexamer bound by Transportin-1 (TRN-1). Among hits, compound H27 inhibited HIV-1 with a low micromolar IC50. Unlike other CA-targeting compounds, H27 did not alter CA assembly or disassembly, inhibited nuclear import specifically, and retained antiviral activity against PF74- and Lenacapavir-resistant mutants. The differential sensitivity of divergent primate lentiviral capsids, capsid stability and H27 escape mutants, together with structural analyses, suggest that H27 makes multiple low affinity contacts with assembled capsid. Interaction experiments indicate that H27 may act by preventing CA from engaging with components of the NPC machinery such as TRN-1. H27 exhibited good metabolic stability in vivo and was efficient against different subtypes and circulating recombinant forms from treatment-naïve patients as well as strains resistant to the four main classes of antiretroviral drugs. This work identifies compounds that demonstrate a novel mechanism of action by specifically blocking HIV-1 nuclear import.

Transcriptomic study reveals alteration in the expression of long non-coding RNAs (lncRNAs) during reversal of HIV-1 latency in monocytic cell line

BACKGROUND

The presence of latent HIV reservoirs continues to be the biggest obstacle to achieving an HIV cure. Thus, long non-coding RNAs (lncRNAs) may serve as the preferred targets for HIV latency reversal. The goal of the study was to identify prospective lncRNAs for subsequent in vitro molecular and functional characterization.

METHODS AND RESULTS

RNA-sequencing was performed in latently HIV-infected monocytic cell line (U1) under stimulated and unstimulated condition using Illumina-HiSeqX platform, followed by its validation using qRT-PCR assay. Gene ontology (GO), KEGG pathway, and co-expression analyses were performed to identify the enriched biological processes and pathways in U1 cells post-stimulation with the latency reversal agent SAHA. A total of 3,576 and 1,467 significantly altered lncRNAs and protein-coding genes respectively, were identified in SAHA-stimulated U1 cells compared to unstimulated ones. The GO and KEGG pathway analyses of the differentially expressed protein-coding genes showed the enrichment of diverse biological processes and pathways respectively, in SAHA-stimulated U1 cells. Co-expression analysis between lncRNAs and protein-coding gene pairs, helped predict potential pathways with which these lncRNAs are associated. Further in vitro validation in HIV-infected monocytes showed that the expression of the top two candidate lncRNAs, LINC01231 and LINC00560, are specific to HIV infection.

CONCLUSION

Transcriptome analysis revealed changes in the expression of numerous lncRNAs and protein-coding genes following stimulation with SAHA. Co-expression analysis identified candidate lncRNAs and their associated biological pathways. However, additional in vitro experimental exploration using gene knockdown strategies is needed to ascertain the specific role of LINC01231 and LINC00560 lncRNAs in latently infected monocytes.

Beyond glycan barriers: non-cognate ligands and protein mimicry approaches to elicit broadly neutralizing antibodies for HIV-1

Human immunodeficiency virus type 1 (HIV-1) vaccine immunogens capable of inducing broadly neutralizing antibodies (bNAbs) remain obscure. HIV-1 evades immune responses through enormous diversity and hides its conserved vulnerable epitopes on the envelope glycoprotein (Env) by displaying an extensive immunodominant glycan shield. In elite HIV-1 viremic controllers, glycan-dependent bNAbs targeting conserved Env epitopes have been isolated and are utilized as vaccine design templates. However, immunological tolerance mechanisms limit the development of these antibodies in the general population. The well characterized bNAbs monoclonal variants frequently exhibit extensive levels of somatic hypermutation, a long third heavy chain complementary determining region, or a short third light chain complementarity determining region, and some exhibit poly-reactivity to autoantigens. This review elaborates on the obstacles to engaging and manipulating the Env glycoprotein as an effective immunogen and describes an alternative reverse vaccinology approach to develop a novel category of bNAb-epitope-derived non-cognate immunogens for HIV-1 vaccine design.

Transcriptional landscape of long non-coding RNAs (lncRNAs) and its implication in viral diseases

Long non-coding RNAs (lncRNAs) are RNA transcripts of size >200 bp that do not translate into proteins. Emerging data revealed that viral infection results in systemic changes in the host at transcriptional level. These include alterations in the lncRNA expression levels and triggering of antiviral immune response involving several effector molecules and diverse signalling pathways. Thus, lncRNAs have emerged as an essential mediatory element at distinct phases of the virus infection cycle. The complete eradication of the viral disease requires more precise and novel approach, thus manipulation of the lncRNAs could be one of them. This review shed light upon the existing knowledge of lncRNAs wherein the implication of differentially expressed lncRNAs in blood-borne, air-borne, and vector-borne viral diseases and its promising therapeutic applications under clinical settings has been discussed. It further enhances our understanding of the complex interplay at host-pathogen interface with respect to lncRNA expression and function.

iTRAQ-based proteomic study on monocyte cell model discovered an association of LAMP2 downregulation with HIV-1 latency

BACKGROUND

Patients with immunodeficiency virus-1 (HIV-1) infection are challenging to be cured completely due to the existence of HIV-1 latency reservoirs. However, the knowledge of the mechanisms and biomarkers associated with HIV-1 latency is limited. Therefore, identifying proteins related to HIV-1 latency could provide new insights into the underlying mechanisms of HIV-1 latency, and ultimately contribute to the eradication of HIV reservoirs.

METHODS

An Isobaric Tags for Relative and Absolute Quantification (iTRAQ)-labeled subcellular proteomic study was performed on an HIV-1 latently infected cell model (U1, a HIV-1-integrated U937 cell line) and its control (U937). Differentially expressed proteins (DEPs) were analyzed using STRING-DB. Selected DEPs were further evaluated by western blotting and multiple reaction monitoring technology in both cell model and patient-derived cluster of differentiation 4 (CD4)+ T cells. Finally, we investigated the relationship between a specific DEP lysosome-associated membrane glycoprotein 2 (LAMP2) and HIV-1 reactivation by panobinostat or lysosome regulation by a lysosomotropic agent hydroxychloroquine in U1 and U937 cells.

RESULTS

In total, 110 DEPs were identified in U1 cells comparing to U937 control cells. Bioinformatics analysis suggested associations of the altered proteins with the immune response and endosomal/lysosomal pathway. LAMP2, leukocyte surface antigen CD47, CD55, and ITGA6 were downregulated in HIV-1 latent cells. Downregulated LAMP2 was further confirmed in resting CD4+ T cells from patients with latent HIV-1 infection. Furthermore, both HIV-1 reactivation by panobinostat and stimulation with hydroxychloroquine upregulated LAMP2 expression.

CONCLUSIONS

Our results indicated the involvement of the endosomal/lysosomal pathway in HIV-1 latency in macrophage cell model. The down-modulation of LAMP2 was associated with HIV latency, and the restoration of LAMP2 expression accompanied the transition of viral latency to active infection. This study provides new insights into the mechanism of HIV-1 latency and potential strategies for eradicating HIV-1 reservoirs by targeting LAMP2 expression.

Replication competent HIV-guided CRISPR screen identifies antiviral factors including targets of the accessory protein Nef

Innate antiviral factors are essential for effective defense against viral pathogens. However, the identity of major restriction mechanisms remains elusive. Current approaches to discover antiviral factors usually focus on the initial steps of viral replication and are limited to a single round of infection. Here, we engineered libraries of >1500 replication-competent HIV-1 constructs each expressing a single gRNAs to target >500 cellular genes for virus-driven discovery of antiviral factors. Passaging in CD4+ T cells robustly enriched HIV-1 encoding sgRNAs against GRN, CIITA, EHMT2, CEACAM3, CC2D1B and RHOA by >50-fold. Using an HIV-1 library lacking the accessory nef gene, we identified IFI16 as a Nef target. Functional analyses in cell lines and primary CD4+ T cells support that the HIV-driven CRISPR screen identified restriction factors targeting virus entry, transcription, release and infectivity. Our HIV-guided CRISPR technique enables sensitive discovery of physiologically relevant cellular defense factors throughout the entire viral replication cycle.

Characterization of HIV-1 Reservoirs in Children and Adolescents: A Systematic Review and Meta-Analysis Toward Pediatric HIV Cure

OBJECTIVE

To conduct a comprehensive, systematic review of the profile of HIV-1 reservoirs in children and adolescents with perinatally acquired HIV infection.

STUDY DESIGN

Randomized and nonrandomized trials, cohort studies, and cross-sectional studies on HIV reservoirs in pediatric populations, published between 2002 and 2022, were included. Archived-drug resistance mutations (ADRMs) and the size of reservoirs were evaluated. Subgroup analyses were performed to characterize further the data, and the meta-analysis was done through random effect models.

RESULTS

Overall, 49 studies from 17 countries worldwide were included, encompassing 2356 perinatally infected participants (48.83% females). There are limited data on the quantitative characterization of viral reservoirs in sub-Saharan Africa, with sensitive methodologies such as droplet digital polymerase chain reaction rarely employed. The overall prevalence of ADRMs was 37.80% (95% CI 13.89-65.17), with 48.79% (95% CI 0-100) in Africa, 42.08% (95% CI 6.68-82.71) in America, 23.88% (95% CI 14.34-34.90) in Asia, and 20.00% (95% CI 10.72-31.17) in Europe, without any difference between infants and adolescents (P = .656). Starting antiretroviral therapy (ART) before 2 months of age limited the levels of HIV-1 DNA (P = .054). Participants with long-suppressed viremia (>5 years) had lower levels of HIV-1 DNA (P = .027). Pre- and post-ART CD4 ≤29% and pre-ART viremia ≥5Log were all found associated with greater levels of HIV-1 DNA (P = .038, P = .047, and P = .041, respectively).

CONCLUSIONS

The pooled prevalence of ADRMs is high in perinatally infected pediatric population, with larger proviral reservoir size driven by delayed ART initiation, a shorter period of viral suppression, and immunovirological failures. Thus, strategies for pediatric HIV functional cure should target children and adolescents with very early ART initiation, immunocompetence, and long-term viral suppression.

Friends and Foes: The Ambivalent Role of Autophagy in HIV-1 Infection

Autophagy has emerged as an integral part of the antiviral innate immune defenses, targeting viruses or their components for lysosomal degradation. Thus, successful viruses, like pandemic human immunodeficiency virus 1 (HIV-1), evolved strategies to counteract or even exploit autophagy for efficient replication. Here, we provide an overview of the intricate interplay between autophagy and HIV-1. We discuss the impact of autophagy on HIV-1 replication and report in detail how HIV-1 manipulates autophagy in infected cells and beyond. We also highlight tissue and cell-type specifics in the interplay between autophagy and HIV-1. In addition, we weigh exogenous modulation of autophagy as a putative double-edged sword against HIV-1 and discuss potential implications for future antiretroviral therapy and curative approaches. Taken together, we consider both antiviral and proviral roles of autophagy to illustrate the ambivalent role of autophagy in HIV-1 pathogenesis and therapy.

Gesicles packaging dCas9-VPR ribonucleoprotein complexes can combine with vorinostat and promote HIV proviral transcription

Despite the success of combination antiretroviral therapy (cART) in HIV treatment, a cure for HIV remains elusive. Scientists postulate that HIV latent reservoirs may be a vital target in curative strategies. Vorinostat is a latency-reversing agent that has demonstrated some effectiveness in reactivating latent HIV, but complementary therapies may be essential to enhance its efficacy. One such approach may utilize the CRISPR-Cas9 system, which has evolved to include transcriptional activators such as dCas9-VPR. In this study, we explored the effects of combining vorinostat coupled with gesicle-mediated delivery of dCas9-VPR in promoting the transcription of integrated HIV proviruses in HIV-NanoLuc CHME-5 microglia and J-Lat 10.6 lymphocytes. We confirmed that dCas9-VPR ribonucleoprotein complexes can be packaged into gesicles and application to cells successfully induced HIV transcription through interactions with the HIV LTR. Vorinostat also induced significant increases in proviral transcription but generated inhibition of cellular proliferation (microglia) or cell viability (lymphocytes) starting at 1,000 nM and higher concentrations. Experiments combining dCas9-VPR gesicles and vorinostat confirmed the enhanced transcriptional activation of the HIV provirus in microglia but not lymphocytes. Thus, a combination of dCas9-VPR gesicles with other latency-reversing agents may provide a complementary method to activate latent HIV in future studies utilizing patient-derived cells or small animal models.

Advancing HIV cure research in low- and middle-income countries requires empowerment of the next generation of scientists

While low- and middle-income countries (LMICs), especially in Southern and Eastern Africa, bear the largest burden of the HIV globally, investigators working on the front lines in these regions are leading a limited number of research efforts, particularly related to HIV cure. Conducting HIV cure research in high-burden HIV LIMCs provides an unparalleled opportunity to formulate innovative research strategies, design trials tailored to the local context, evaluate clinical outcomes within key and vulnerable populations, meaningful involvement of stakeholders, and to shape policies in areas where HIV prevention and cure interventions can yield the most significant impact. Further, the high prevalence of infection, with varied HIV strains affecting large diverse populations, creates a unique environment for studies that would not be feasible in any other part of the world. This underscores the critical importance of addressing obstacles to unlock the full potential of research efforts in these regions. In this viewpoint, we identify significant challenges facing early career investigators in LMICs, particularly in Africa, that hinder their full engagement in HIV cure research. Drawing examples from the International AIDS Society's Research-for-Cure Academy, we provide practical recommendations to overcome barriers that include limited access to funding, effective mentors, educational and career development opportunities, coupled with inadequate investment in infrastructure that contribute towards the limited number of investigators from high-burden HIV LIMCs who are spearheading cutting-edge cure research. Addressing these challenges is crucial to empower investigators who possess unique insights and expertise, and who are well positioned to lead HIV cure-related research efforts. We acknowledge and welcome initiatives that promote capacity building and knowledge exchange between early-career investigators in LMICs and their peers and scientific leaders from high-income countries (HICs). Prioritizing investment in global collaboration and partnership will play a pivotal role in empowering the next generation of African scientists and clinicians. To expedite advancements of cure-related strategies that will be effective in high-burden HIV LMICs, we endorse the sustainable expansion of these pivotal initiatives in these regions, to enhance their effectiveness and hasten progress in the pursuit of a global HIV cure.

A truncated HIV Tat demonstrates potent and specific latency reversal activity

A major barrier to HIV-1 cure is caused by the pool of latently infected CD4 T-cells that persist under combination antiretroviral therapy (cART). This latent reservoir is capable of producing replication-competent infectious viruses once prolonged suppressive cART is withdrawn. Inducing the reactivation of HIV-1 gene expression in T-cells harboring a latent provirus in people living with HIV-1 under cART may result in depletion of this latent reservoir due to cytopathic effects or immune clearance. Studies have investigated molecules that reactivate HIV-1 gene expression, but to date, no latency reversal agent has been identified to eliminate latently infected cells harboring replication-competent HIV in cART-treated individuals. Stochastic fluctuations in HIV-1 tat gene expression have been described and hypothesized to allow the progression into proviral latency. We hypothesized that exposing latently infected CD4+ T-cells to Tat would result in effective latency reversal. Our results indicate the capacity of a truncated Tat protein and mRNA to reactivate HIV-1 in latently infected T-cells ex vivo to a similar degree as the protein kinase C agonist: phorbol 12-myristate 13-acetate, without T-cell activation or any significant transcriptome perturbation.

Bcl-2 Antagonist Obatoclax Reactivates Latent HIV-1 via the NF-κB Pathway and Induces Latent Reservoir Cell Apoptosis in Latently Infected Cells

The implementation of combined antiretroviral therapy (cART) has rendered HIV-1 infection clinically manageable and efficiently improves the quality of life for patients with AIDS. However, the persistence of a latent HIV-1 reservoir is a major obstacle to achieving a cure for AIDS. A "shock and kill" strategy aims to reactivate latent HIV and then kill it by the immune system or cART drugs. To date, none of the LRA candidates has yet demonstrated effectiveness in achieving a promising functional cure. Interestingly, the phosphorylation and activation of antiapoptotic Bcl-2 protein induce resistance to apoptosis during HIV-1 infection and the reactivation of HIV-1 latency in central memory CD4+ T cells from HIV-1-positive patients. Therefore, a Bcl-2 antagonist might be an effective LRA candidate for HIV-1 cure. In this study, we reported that a pan-Bcl-2 antagonist obatoclax induces HIV-1 reactivation in latently infected cell lines in vitro and in PBMCs/CD4+ T cells of HIV-infected individuals ex vivo. Obatoclax promotes HIV-1 transcriptional initiation and elongation by regulating the NF-κB pathway. Obatoclax activates caspase 8 and does not induce the phosphorylation of the antiapoptotic protein Bcl-2 in latent HIV-1 infected cell lines. More importantly, it preferentially induces apoptosis in latently infected cells. In addition, obatoclax exhibited potent anti-HIV-1 activity on target cells. The abilities to reactivate latent HIV-1 reservoirs, inhibit HIV-1 infection, and induce HIV-1 latent cell apoptosis make obatoclax worth investigating for development as an ideal LRA for use in the "shock and kill" approach.

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.

Transmitted/founder SHIV.D replicates in the brain, causes neuropathogenesis, and persists on combination antiretroviral therapy in rhesus macaques

A biologically relevant non-human primate (NHP) model of HIV persistence in the central nervous system (CNS) is necessary. Most current NHP/SIV models of HIV infection fail to recapitulate viral persistence in the CNS without encephalitis or fail to employ viruses that authentically represent the ongoing HIV-1 pandemic. Here, we demonstrate viral replication in the brain and neuropathogenesis after combination antiretroviral therapy (ART) in rhesus macaques (RMs) using novel macrophage-tropic transmitted/founder (TF) simian-human immunodeficiency virus SHIV.D.191,859 (SHIV.D). Quantitative immunohistochemistry (IHC) and DNA/RNAscope in situ hybridization (ISH) were performed on three brain regions from six SHIV.D-infected RMs; two necropsied while viremic, two during analytical treatment interruptions, and two on suppressive ART. We demonstrated myeloid-mediated neuroinflammation, viral replication, and proviral DNA in the brain in all animals. These results demonstrate that TF SHIV.D models native HIV-1 CNS replication, pathogenesis, and persistence on ART in rhesus macaques.

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.

Lipid nanocarrier targeting activated macrophages for antiretroviral therapy of HIV reservoir

Aim: To develop lipid nano-antiretrovirals (LNAs) for the treatment of HIV-infected macrophages. Materials & methods: LNAs were prepared with docosahexaenoic acid to facilitate brain penetration and surface-decorated with folate considering that infected macrophages often overexpress folate receptors. Results: Folate-decorated LNAs loading rilpivirine (RPV) were efficiently taken up by folate receptor-expressing cell types including activated macrophages. The intracellular Cmax of the RPV-LNAs in activated macrophages was 2.54-fold and the area under the curve was 3.4-fold versus free RPV, translating to comparable or higher (p < 0.01; RPV ≤6.5 ng/ml) activities against HIV infectivity and superior protection (p < 0.05) against HIV cytotoxicity. LNAs were also effective in monocyte-derived macrophages. Conclusion: These findings demonstrate the potential of LNAs for the treatment of infected macrophages, which are key players in HIV reservoirs.

HIV Pre-Exposure Prophylaxis, Blood Donor Deferral, Occult Infection, and Risk of HIV Transmission by Transfusion: A Fine Balance Between Evidence-Based Donor Selection Criteria and Transfusion Safety

Pre- and postexposure prophylaxis for human immunodeficiency virus (HIV) are key to reducing the transmission of this virus. Furthermore, low-toxicity, long-acting formulations provide additional clinical benefits, in particular easier adherence to treatment and prevention. However, breakthrough HIV infections can occur despite the use of pre-exposure prophylaxis (PrEP), mainly due to suboptimal adherence or multi-drug resistant HIV strains. Albeit rare, PrEP breakthrough infections have also been reported in fully adherent patients. Should such breakthrough infection occur in an eligible blood donor, PrEP might suppress viremia and delay antibody seroconversion, thereby masking the infection and increasing the risk of transfusion transmission. This possibility has raised concerns in the blood transfusion community but remains little documented. Therefore, a literature search was performed to assess the state of knowledge on the risk of PrEP breakthrough infection, with a particular focus on the risk of HIV entering the blood supply. Evidently, PrEP breakthrough infections are rare, although the risk is not zero. Moreover, a fraction of individuals - including blood donors - do not disclose PrEP use according to various surveys and measurements of HIV PrEP analytes. Additionally, viremia and seroconversion may remain undetectable or close to the limit of detection for a long time after cessation of PrEP, particularly with long-acting antiretrovirals. Therefore, current recommendations to defer donors for at least 3 months after the last dose of oral PrEP or 2 years for long-acting PrEP appear justified, as they safeguard the blood supply and public trust toward the system. These recommendations help to safeguard blood safety and public trust in the blood supply.

HIV-1 Transcriptional Activator Tat Inhibits IL2 Expression by Preventing the Presence of Pol II on the IL2 Promoter

HIV-1 infection leads to a gradual loss of T helper cells, chronic immune activation, and eventual immune system breakdown. HIV-1 causes deregulation of the expression of IL-2, a cytokine important for T helper cell growth and survival, which is downregulated in HIV-1 patients. The present study addresses the regulation of IL2 expression via HIV-1 Tat transcriptional activator. We used J-LAT cells, a T cell line that serves as a latency model for studies of HIV-1 expression in T cells, and as controls a T cell line lacking HIV-1 elements and a T cell line with a stably integrated copy of the HIV-1-LTR promoter. We show that endogenously expressed Tat inhibits IL2 transcription in J-Lat cells via its presence in the ARRE-1/2 elements of the IL2 promoter and that the inhibition of IL2 expression is mediated by Tat inhibiting Pol II activity at the IL2 promoter, which is mediated by preventing the presence of Pol II at the ARRE-1/2 elements. Overall, Tat is present at the IL2 promoter, apart from its cognate HIV-1 LTR target. This supports our current knowledge of how HIV-1 affects the host transcriptional machinery and reflects the potential of Tat to disrupt transcriptional regulation of host genes to manipulate cell responses.

Chemical inhibition of DPP9 sensitizes the CARD8 inflammasome in HIV-1-infected cells

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) induce pyroptosis of HIV-1-infected CD4+ T cells through induction of intracellular HIV-1 protease activity, which activates the CARD8 inflammasome. Because high concentrations of NNRTIs are required for efficient elimination of HIV-1-infected cells, it is important to elucidate ways to sensitize the CARD8 inflammasome to NNRTI-induced activation. We show that this sensitization can be achieved through chemical inhibition of the CARD8 negative regulator DPP9. The DPP9 inhibitor Val-boroPro (VbP) can kill HIV-1-infected cells without the presence of NNRTIs and act synergistically with NNRTIs to promote clearance of HIV-1-infected cells in vitro and in humanized mice. More importantly, VbP is able to enhance clearance of residual HIV-1 in CD4+ T cells isolated from people living with HIV (PLWH). We also show that VbP can partially overcome NNRTI resistance. This offers a promising strategy for enhancing NNRTI efficacy in the elimination of HIV-1 reservoirs in PLWH.

Use of laboratory-developed assays in global HIV-1 treatment-monitoring and research

There has been a surge in the emergence of HIV-1 drug resistance in Low and Middle-Income Countries (LMICs) due to poor drug-adherence and limited access to viral load testing, the current standard for treatment-monitoring. It is estimated that only 75% of people living with HIV (PLWH) worldwide have access to viral load testing. In LMICs, this figure is below 50%. In a recent WHO survey in mostly LMICs, 21 out of 30 countries surveyed found HIV-1 first-line pre-treatment drug resistance in over 10% of study participants. In the worst-affected regions, up to 68% of infants born to HIV-1 positive mothers were found to harbour first-line HIV-1 treatment resistance. This is a huge public health concern. Greater access to treatment-monitoring is required in LMICs if the UNAIDS "third 95" targets are to be achieved by 2030. Here, we review the current challenges of viral load testing and present the case for greater utilization of Laboratory-based assays that quantify intracellular HIV-1 RNA and/or DNA to provide broader worldwide access to HIV-1 surveillance, drug-resistance monitoring, and cure-research.

Enhancing HIV-1 latency reversal through regulating the elongating RNA Pol II pause-release by a small-molecule disruptor of PAF1C

The polymerase-associated factor 1 complex (PAF1C) is a key, post-initiation transcriptional regulator of both promoter-proximal pausing and productive elongation catalyzed by RNA Pol II and is also involved in transcriptional repression of viral gene expression during human immunodeficiency virus-1 (HIV-1) latency. Using a molecular docking-based compound screen in silico and global sequencing-based candidate evaluation in vivo, we identified a first-in-class, small-molecule inhibitor of PAF1C (iPAF1C) that disrupts PAF1 chromatin occupancy and induces global release of promoter-proximal paused RNA Pol II into gene bodies. Transcriptomic analysis revealed that iPAF1C treatment mimics acute PAF1 subunit depletion and impairs RNA Pol II pausing at heat shock-down-regulated genes. Furthermore, iPAF1C enhances the activity of diverse HIV-1 latency reversal agents both in cell line latency models and in primary cells from persons living with HIV-1. In sum, this study demonstrates that efficient disruption of PAF1C by a first-in-class, small-molecule inhibitor may have therapeutic potential for improving current HIV-1 latency reversal strategies.

Assessing the Impact of Persistent HIV Infection on Innate Lymphoid Cells Using In Vitro Models

Pathogens that persist in their host induce immune dysfunctions even in the absence of detectable replication. To better understand the phenotypic and functional changes that persistent infections induce in sentinel innate immune cells, we developed human PBMC-based HIV models of persistent infection. Autologous nonactivated PBMCs were cocultured with chronically infected, acutely infected, or uninfected cells and were then analyzed by unsupervised high-dimensional flow cytometry. Using this approach, we identified prevalent patterns of innate immune dysfunctions associated with persistent HIV infections that at least in part mirror immune dysfunctions observed in patients. In one or more models of chronic infection, bystander CD16+ NK cells expressing markers of activation, such as CD94, CD45RO, CD62L, CD69, CD25, and immune checkpoints PD1, Tim3, TIGIT, NKG2A and Lag3, were significantly reduced. Conversely, helper ILC subsets expressing PDL1/PDL2 were significantly enriched in chronic infection compared with either uninfected or acute infection, suggesting that chronic HIV-1 infection was associated with an inhibitory environment for bystander ILC and NK subsets. The cell-based models of persistent infection that we describe here provide versatile tools to explore the molecular mechanisms of these immune dysfunctions and unveil the contribution of innate immunity in sustaining pathogen persistence.

Controversies in the Design of Strategies for the Cure of HIV Infection

The cure for chronic human immunodeficiency virus (HIV) infections has been a goal pursued since the antiretroviral therapy that improved the clinical conditions of patients became available. However, the exclusive use of these drugs is not enough to achieve a cure, since the viral load rebounds when the treatment is discontinued, leading to disease progression. There are several theories and hypotheses about the biological foundations that prevent a cure. The main obstacle appears to be the existence of a latent viral reservoir that cannot be eliminated pharmacologically. This concept is the basis of the new strategies that seek a cure, known as kick and kill. However, there are other lines of study that recognize mechanisms of persistent viral replication in patients under effective treatment, and that would modify the current lines of research on the cure of HIV. Given the importance of these concepts, in this work, we propose to review the most recent evidence on these hypotheses, covering both the evidence that is positioned in favor and against, trying to expose what are some of the challenges that remain to be resolved in this field of research.

A CRISPR-Cas Cure for HIV/AIDS

Human immunodeficiency virus (HIV) infections and HIV-induced acquired immunodeficiency syndrome (AIDS) continue to represent a global health burden. There is currently no effective vaccine, nor any cure, for HIV infections; existing antiretroviral therapy can suppress viral replication, but only as long as antiviral drugs are taken. HIV infects cells of the host immune system, and it can establish a long-lived viral reservoir, which can be targeted and edited through gene therapy. Gene editing platforms based on the clustered regularly interspaced palindromic repeat-Cas system (CRISPR-Cas) have been recognized as promising tools in the development of gene therapies for HIV infections. In this review, we evaluate the current landscape of CRISPR-Cas-based therapies against HIV, with an emphasis on the infection biology of the virus as well as the activity of host restriction factors. We discuss the potential of a combined CRISPR-Cas approach that targets host and viral genes to activate antiviral host factors and inhibit viral replication simultaneously. Lastly, we focus on the challenges and potential solutions of CRISPR-Cas gene editing approaches in achieving an HIV cure.

MIR-29A-3P, MIR-29C-3P, MIR-146B-5P AND MIR-150-5P, Their Target Genes and lncrnas in HIV Infection: A Bioinformatic Study

INTRODUCTION

Increasing evidence suggests that microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) have emerged as attractive targets in viral infections, including Human immunodeficiency virus (HIV).

OBJECTIVE

To deepen the understanding of the molecular mechanisms that lead to HIV and provide potential targets for the future development of molecular therapies for its treatment.

METHODS

Four miRNAs were selected as candidates based on a previous systematic review. A combination of bioinformatic analyses was performed to identify their target genes, lncRNAs and biological processes that regulate them.

RESULTS

In the constructed miRNA-mRNA network, 193 gene targets are identified. These miRNAs potentially control genes from several important processes, including signal transduction and cancer. LncRNA-XIST, lncRNA-NEAT1 and lncRNA-HCG18 interact with all four miRNAs.

CONCLUSION

This preliminary result forms the basis for improving reliability in future studies to fully understand the role these molecules and their interactions play in HIV.

The CARD8 inflammasome in HIV infection

The biggest challenge to immune control of HIV infection is the rapid within-host viral evolution, which allows selection of viral variants that escape from T cell and antibody recognition. Thus, it is impossible to clear HIV infection without targeting "immutable" components of the virus. Unlike the adaptive immune system that recognizes cognate epitopes, the CARD8 inflammasome senses the essential enzymatic activity of the HIV-1 protease, which is immutable for the virus. Hence, all subtypes of HIV clinical isolates can be recognized by CARD8. In HIV-infected cells, the viral protease is expressed as a subunit of the viral Gag-Pol polyprotein and remains functionally inactive prior to viral budding. A class of anti-HIV drugs, the non-nucleoside reverse transcriptase inhibitors (NNRTIs), can promote Gag-pol dimerization and subsequent premature intracellular activation of the viral protease. NNRTI treatment triggers CARD8 inflammasome activation, which leads to pyroptosis of HIV-infected CD4⁺ T cells and macrophages. Targeting the CARD8 inflammasome can be a potent and broadly effective strategy for HIV eradication.

Determinants of Retroviral Integration and Implications for Gene Therapeutic MLV-Based Vectors and for a Cure for HIV-1 Infection

To complete their replication cycle, retroviruses need to integrate a DNA copy of their RNA genome into a host chromosome. Integration site selection is not random and is driven by multiple viral and cellular host factors specific to different classes of retroviruses. Today, overwhelming evidence from cell culture, animal experiments and clinical data suggests that integration sites are important for retroviral replication, oncogenesis and/or latency. In this review, we will summarize the increasing knowledge of the mechanisms underlying the integration site selection of the gammaretrovirus MLV and the lentivirus HIV-1. We will discuss how host factors of the integration site selection of retroviruses may steer the development of safer viral vectors for gene therapy. Next, we will discuss how altering the integration site preference of HIV-1 using small molecules could lead to a cure for HIV-1 infection.

HIV Infection and Oral Manifestations: An Update

Human immunodeficiency virus (HIV) causes a complete depletion of the immune system; it has been a major health issue around the world since the 1980s, and due to the reduction of CD4+ T lymphocytes levels, it can trigger various opportunistic infections. Oral lesions are usually accurate indicators of immunosuppression because these oral manifestations may occur as a result of the compromised immune system caused by HIV infection; therefore, oral lesions might be initial and common clinical features in people living with HIV. So, it is necessary to evaluate and understand the mechanism, prevalence, and risk factors of oral lesions to avoid the increase morbidity among those with oral diseases.

Role of CXCR5+ CD8+ T cells in human immunodeficiency virus-1 infection

Human immunodeficiency virus (HIV) infection can be effectively suppressed by life-long administration of combination antiretroviral therapy (cART). However, the viral rebound can occur upon cART cessation due to the long-term presence of HIV reservoirs, posing a considerable barrier to drug-free viral remission. Memory CD4⁺ T cell subsets, especially T follicular helper (T _FH ) cells that reside in B-cell follicles within lymphoid tissues, are regarded as the predominant cellular compartment of the HIV reservoir. Substantial evidence indicates that HIV-specific CD8⁺ T cell-mediated cellular immunity can sustain long-term disease-free and transmission-free HIV control in elite controllers. However, most HIV cure strategies that rely on expanded HIV-specific CD8⁺ T cells for virus control are likely to fail due to cellular exhaustion and T _FH reservoir-specialized anatomical structures that isolate HIV-specific CD8⁺ T cell entry into B-cell follicles. Loss of stem-like memory properties is a key feature of exhaustion. Recent studies have found that CXC chemokine receptor type 5 (CXCR5)-expressing HIV-specific CD8⁺ T cells are memory-like CD8⁺ T cells that can migrate into B-cell follicles to execute inhibition of viral replication. Furthermore, these unique CD8⁺ T cells can respond to immune checkpoint blockade (ICB) therapy. In this review, we discuss the functions of these CD8⁺ T cells as well as the translation of findings into viable HIV treatment and cure strategies.

Associations between NK Cells in Different Immune Organs and Cellular SIV DNA and RNA in Regional HLADR- CD4+ T Cells in Chronically SIVmac239-Infected, Treatment-Naïve Rhesus Macaques

With the development of NK cell-directed therapeutic strategies, the actual effect of NK cells on the cellular SIV DNA levels of the virus in SIV-infected macaques in vivo remains unclear. In this study, five chronically SIV_mac239-infected, treatment-naïve rhesus macaques were euthanized, and the blood, spleen, pararectal/paracolonic lymph nodes (PaLNs), and axillary lymph nodes (ALNs) were collected. The distributional, phenotypic, and functional profiles of NK cells were detected by flow cytometry. The highest frequency of NK cells was found in PBMC, followed by the spleen, while only 0~0.5% were found in LNs. Peripheral NK cells also exhibited higher cytotoxic potential (CD56^- CD16⁺ NK subsets) and IFN-γ-producing capacity but low PD-1 and Tim-3 levels than those in the spleen and LNs. Our results demonstrated a significant positive correlation between the frequency of NK cells and the ratios of cellular SIV DNA/RNA in HLADR^- CD4⁺ T cells (r = 0.6806, p < 0.001) in SIV-infected macaques, despite no discrepancies in the cellular SIV DNA or RNA levels that were found among the blood, spleen, and LNs. These findings showed a profile of NK cell frequencies and NK cytotoxicity levels in different immune organs from chronically SIV_mac239-infected, treatment-naïve rhesus macaques. It was suggested that NK cell frequencies could be closely related to SIV DNA/RNA levels, which could affect the transcriptional activity of SIV proviruses. However, the cytotoxicity effect of NK cells on the latent SIV viral load in LNs could be limited due to the sparse abundance of NK cells in LNs. The development of NK cell-directed treatment approaches aiming for HIV clearance remains challenging.

Potential HIV latency-reversing agents with STAT1-activating activity from the leaves of Wikstroemia chamaedaphne

Developing highly effective HIV latency-reversing agent is an inportmant approach for the treatment of AIDS via the "shock and kill" of latent HIV. In this study, two unreported modified daphnane-type diterpenes (chamaedaphnelide A and epi-chamaedaphnelide A) and one unreported tigliane-type diterpene (chamaedaphnelide B), along with four known daphnane-type diterpenes and one known tigliane-type diterpene were obtained from the leaves of Wikstroemia chamaedaphne. Chamaedaphnelide A and epi-chamaedaphnelide A represents the first A ring cleavage daphnane-type backbone. Chamaedaphnelide A, epi-chamaedaphnelide A, chamaedaphnelide B, and 6α,7α-epoxy-5β-hydroxy-12-deoxyphorbol-13-decanoate showed HIV latency-reversing activity, especially chamaedaphnelide B and 6α,7α-epoxy-5β-hydroxy-12-deoxyphorbol-13-decanoate displayed equally potential to positive drugs prostratin with reversing latent HIV on more than 100-fold compared to unstimulated cells. Furthermore, the activation of STAT1 was involved in the HIV latency-reversing activity of these diterpenes, firstly demonstrating that daphnane- and tigliane-type diterpenes can rapidly activate STAT1 activity. Indeed, these results also supported that activating STAT1 activity is a pathway for reversing latent HIV.

Sustained Virologic Suppression Reduces HIV-1 DNA Proviral Levels and HIV Antibodies in Perinatally HIV-Infected Children Followed from Birth

The extent to which perinatally HIV-infected children, following cART initiation, develop a low proviral reservoir burden over time, as measured by HIV DNA droplet-digital polymerase chain reaction (ddPCR) and the effect on HIV antibody is not well characterized. We measured proviral HIV DNA and plasma RNA virus load (VL) in 37 perinatally HIV-infected children at 6 months of age who initiated stable cART. At 6-11 years of age, HIV proviral DNA, HIV VL (RNA), and HIV antibody by Western Blot (WB) were assessed. CART was initiated before 6 months of age in 13 children and after 6 months in 24. At school age, the HIV DNA levels did not differ by the timing of cART, and the HIV DNA levels were lower in children with negative/indeterminate WB (p = 0.0256). Children with undetectable HIV RNA VL > 50% of the time since cART initiation had lower median DNA VL than children with undetectable VL < 50% of the time (p = 0.07). Long-term viral suppression in perinatally HIV-infected children is associated with a decrease in HIV antibodies and reduced HIV reservoirs.

HIV-1 Infection of Long-Lived Hematopoietic Precursors In Vitro and In Vivo

Latent reservoirs in human-immunodeficiency-virus-1 (HIV-1)-infected individuals represent a major obstacle in finding a cure for HIV-1. Hematopoietic stem and progenitor cells (HSPCs) have been described as potential HIV-1 targets, but their roles as HIV-1 reservoirs remain controversial. Here we provide additional evidence for the susceptibility of several distinct HSPC subpopulations to HIV-1 infection in vitro and in vivo. In vitro infection experiments of HSPCs were performed with different HIV-1 Env-pseudotyped lentiviral particles and with replication-competent HIV-1. Low-level infection/transduction of HSPCs, including hematopoietic stem cells (HSCs) and multipotent progenitors (MPP), was observed, preferentially via CXCR4, but also via CCR5-mediated entry. Multi-lineage colony formation in methylcellulose assays and repetitive replating of transduced cells provided functional proof of susceptibility of primitive HSPCs to HIV-1 infection. Further, the access to bone marrow samples from HIV-positive individuals facilitated the detection of HIV-1 gag cDNA copies in CD34+ cells from eight (out of eleven) individuals, with at least six of them infected with CCR5-tropic HIV-1 strains. In summary, our data confirm that primitive HSPC subpopulations are susceptible to CXCR4- and CCR5-mediated HIV-1 infection in vitro and in vivo, which qualifies these cells to contribute to the HIV-1 reservoir in patients.

The reservoir of latent HIV

The persistence of latent reservoir of the human immunodeficiency virus (HIV) is currently the major challenge in curing HIV infection. After HIV infects the human body, the latent HIV is unable to be recognized by the body’s immune system. Currently, the widely adopted antiretroviral therapy (ART) is also unble to eliminate it, thus hindering the progress of HIV treatment. This review discusses the existence of latent HIV vault for HIV treatment, its formation and factors affecting its formation, cell, and tissue localization, methods for detection and removing latent reservoir, to provide a comprehensive understanding of latent HIV vault, in order to assist in the future research and play a potential role in achieving HIV treatment.

Patent Highlights February-March 2022

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

From HIV to COVID-19, Molecular mechanisms of pathogens' trade-off and persistence in the community, potential targets for new drug development

BACKGROUND

On the staggering emergence of the Omicron variant, numerous questions arose about the evolution of virulence and transmissibility in microbes.

MAIN BODY OF THE ABSTRACT

The trade-off hypothesis has long speculated the exchange of virulence for the sake of superior transmissibility in a wide array of pathogens. While this certainly applies to the case of the Omicron variant, along with influenza virus, various reports have been allocated for an array of pathogens such as human immunodeficiency virus (HIV), malaria, hepatitis B virus (HBV) and tuberculosis (TB). The latter abide to another form of trade-off, the invasion-persistence trade-off. In this study, we aim to explore the molecular mechanisms and mutations of different obligate intracellular pathogens that attenuated their more morbid characters, virulence in acute infections and invasion in chronic infections.

SHORT CONCLUSION

Recognizing the mutations that attenuate the most morbid characters of pathogens such as virulence or persistence can help in tailoring new therapies for such pathogens. Targeting macrophage tropism of HIV by carbohydrate-binding agents, or targeting the TMPRSS2 receptors to prevent pulmonary infiltrates of COVID-19 is an example of how important is to recognize such genetic mechanisms.

Targeted Nanocarrier Delivery of RNA Therapeutics to Control HIV Infection

Our understanding of HIV infection has greatly advanced since the discovery of the virus in 1983. Treatment options have improved the quality of life of people living with HIV/AIDS, turning it from a fatal disease into a chronic, manageable infection. Despite all this progress, a cure remains elusive. A major barrier to attaining an HIV cure is the presence of the latent viral reservoir, which is established early in infection and persists for the lifetime of the host, even during prolonged anti-viral therapy. Different cure strategies are currently being explored to eliminate or suppress this reservoir. Several studies have shown that a functional cure may be achieved by preventing infection and also inhibiting reactivation of the virus from the latent reservoir. Here, we briefly describe the main HIV cure strategies, focussing on the use of RNA therapeutics, including small interfering RNA (siRNA) to maintain HIV permanently in a state of super latency, and CRISPR gRNA to excise the latent reservoir. A challenge with progressing RNA therapeutics to the clinic is achieving effective delivery into the host cell. This review covers recent nanotechnological strategies for siRNA delivery using liposomes, N-acetylgalactosamine conjugation, inorganic nanoparticles and polymer-based nanocapsules. We further discuss the opportunities and challenges of those strategies for HIV treatment.

Cytokine Adjuvants IL-7 and IL-15 Improve Humoral Responses of a SHIV LentiDNA Vaccine in Animal Models

HIV-1 remains a major public health issue worldwide in spite of efficacious antiviral therapies, but with no cure or preventive vaccine. The latter has been very challenging, as virus infection is associated with numerous escape mechanisms from host specific immunity and the correlates of protection remain incompletely understood. We have developed an innovative vaccine strategy, inspired by the efficacy of live-attenuated virus, but with the safety of a DNA vaccine, to confer both cellular and humoral responses. The CAL-SHIV-IN− lentiDNA vaccine comprises the backbone of the pathogenic SHIVKU2 genome, able to mimic the early phase of viral infection, but with a deleted integrase gene to ensure safety precluding integration within the host genome. This vaccine prototype, constitutively expressing viral antigen under the CAEV LTR promoter, elicited a variety of vaccine-specific, persistent CD4 and CD8 T cells against SIV-Gag and Nef up to 80 weeks post-immunization in cynomolgus macaques. Furthermore, these specific responses led to antiviral control of the pathogenic SIVmac251. To further improve the efficacy of this vaccine, we incorporated the IL-7 or IL-15 genes into the CAL-SHIV-IN− plasmid DNA in efforts to increase the pool of vaccine-specific memory T cells. In this study, we examined the immunogenicity of the two co-injected lentiDNA vaccines CAL-SHIV-IN− IRES IL-7 and CAL-SHIV-IN− IRES IL-15 in BALB/cJ mice and rhesus macaques and compared the immune responses with those generated by the parental vaccine CAL-SHIV-IN−. This co-immunization elicited potent vaccine-specific CD4 and CD8 T cells both in mice and rhesus macaques. Antibody-dependent cell-mediated cytotoxicity (ADCC) antibodies were detected up to 40 weeks post-immunization in both plasma and mucosal compartments of rhesus macaques and were enhanced by the cytokines.

TGF-β Signaling Supports HIV Latency in a Memory CD4+ T Cell Based In Vitro Model

During antiretroviral therapy (ART), HIV-1 persists as a latent reservoir in CD4+ T cell subsets in central (TCM), transitional (TTM) and effector memory (TEM) CD4+ T cells. Understanding the mechanisms that support HIV-1 latency in each of these subsets is essential to the identification of cure strategies to eliminate them. Due to the very low frequency of latently infected cells in vivo, model systems that can accurately reflect the heterogenous population of HIV-1 infected cells are a critical component in HIV cure discoveries. Here, we describe a novel primary cell-based model of HIV-1 latency that recapitulates the complex dynamics of the establishment and maintenance of the latent reservoir in different memory T cell subsets. The latency and reversion assay (LARA ) culture conditions uniquely retain phenotypically and transcriptionally distinct memory CD4+ T cell subsets that allow in a single assay to assess LRA activity in each memory subset and differential examination of the dynamics of HIV latency reversal.

A synthetic resveratrol analog termed Q205 reactivates latent HIV-1 through activation of P-TEFb

The persistence of HIV-1 latent reservoir creates the major obstacle toward an HIV-1 cure. The "shock and kill" strategy aims to reverse HIV-1 proviral latency using latency-reversing agents (LRAs), thus boosting immune recognition and clearance to residual infected cells. Unfortunately, to date, none of these tested LRA candidates has been demonstrated effectiveness and/or safety in reactivation HIV-1 latency. The discovery and development of effective, safe and affordable LRA candidates are urgently needed for creating an HIV-1 functional cure. Here, we designed and synthesized a series of small-molecule phenoxyacetic acid derivatives based on the resveratrol scaffold and found one of them, named 5, 7-dimethoxy-2-(5-(methoxymethyl) furan-2-yl) quinazolin-4(3H)-one (Q205), effectively reactivated latent HIV-1 in latent HIV-1-infected cells without a corresponding increase in induction of potentially damaging cytokines. The molecular mechanism of Q205 is shown to increase the phosphorylation of the CDK9 T-loop at position Thr186, dissociate positive transcription elongation factor b (P-TEFb) from BRD4, and promote the Tat-mediated HIV-1 transcription and RNA polymerase II (RNAPII) C-terminal domain (CTD) on Ser (CTD-Ser2P) to bind to the HIV promoter. This study provides a unique insight into resveratrol modified derivatives as promising leads for preclinical LRAs, which in turn may help toward inhibitor design and chemical optimization for improving HIV-1 shock-and kill-based efforts.

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.

Design and Synthesis of Hybrid Compounds as Epigenetic Modifiers

Epigenetic modifiers acting through polypharmacology mechanisms are promising compounds with which to treat several infectious diseases. Histone deacetylase (HDAC) enzymes, mainly class I, and extra-terminal bromodomains (BET) are involved in viral replication and the host response. In the present study, 10 compounds were designed, assisted by molecular docking, to act against HDAC class I and bromodomain-4 (BRD4). All the compounds were synthesized and characterized by analytical methods. Enzymatic assays were performed using HDAC-1, -4, and -11 and BRD4. Compounds (2-10) inhibited both HDAC class I, mainly HDAC-1 and -2, and reduced BRD4 activity. For HDAC-1, the inhibitory effect ranged from 8 to 95%, and for HDAC-2, these values ranged from 10 to 91%. Compounds (2-10) decreased the BRD4 activity by up to 25%. The multi-target effects of these compounds show desirable properties that could help to combat viral infections by acting through epigenetic mechanisms.

HIV-1 persistence in the CNS: Mechanisms of latency, pathogenesis and an update on eradication strategies

Despite four decades of research into the human immunodeficiency virus (HIV-1), a successful strategy to eradicate the virus post-infection is lacking. The major reason for this is the persistence of the virus in certain anatomical reservoirs where it can become latent and remain quiescent for as long as the cellular reservoir is alive. The Central Nervous System (CNS), in particular, is an intriguing anatomical compartment that is tightly regulated by the blood-brain barrier. Targeting the CNS viral reservoir is a major challenge owing to the decreased permeability of drugs into the CNS and the cellular microenvironment that facilitates the compartmentalization and evolution of the virus. Therefore, despite effective antiretroviral (ARV) treatment, virus persists in the CNS, and leads to neurological and neurocognitive deficits. To date, viral eradication strategies fail to eliminate the virus from the CNS. To facilitate the improvement of the existing elimination strategies, as well as the development of potential therapeutic targets, the aim of this review is to provide an in-depth understanding of HIV latency in CNS and the onset of HIV-1 associated neurological disorders.