Reduction of HIV-1 in blood and lymph nodes following potent antiretroviral therapy and the virologic correlates of treatment failure

Time to Treatment Failure and Its Predictors Among Second-Line ART Clients in Amhara Region, Ethiopia: A Retrospective Follow-Up Study

Background

Second-line antiretroviral treatment failure has become a major public health issue, and the time to treatment failure among second-line ART clients varies globally, and the Sub-Saharan African region having a high rate of second-line ART treatment failures. In addition, after the ART treatment guideline changed there is limited information on Ethiopia. Therefore, this study aimed to assess time to treatment failure and its determinants among second-line ART clients in Amhara Region, Ethiopia.

Methods

A multi-centered retrospective follow-up study was conducted. A random sample of 860 people on second-line ART was selected by using a computer-generated simple random sampling technique from January 30, 2016, to January 30, 2021, at the University of Gondar Compressive Specialized Hospital, Felege Hiwot Compressive Specialized Referral Hospital, and Debre Tabor Compressive Specialized Referral Hospital, in Amhara region, Ethiopia. Data was captured using a checklist.

Results

A total of 81 (9.4%) ART clients developed second-line treatment failure, with a median follow-up time of 29 months with an interquartile range (IQR: 18, 41]. The risk of second-line treatment failure is higher among patients aged 15 to 30 years (adjusted hazard ratio (AHR) = 2.01, 95% confidence interval (CI): [1.16, 3.48]). Being unable to read and write (AHR = 1.312, 95% CI: [1.068, 1.613]), and poor ART drug adherence (AHR = 3.067, 95% CI: [1.845, 5.099]) were significant predictors of second-line ART treatment failures.

Conclusion

In the current study, the time to second-line ART treatment failure was high compared with a previous similar study in Ethiopia. Factors like being younger age, ART clients who are not being able to read and write, and having poor ART drug adherence was significant predictors of second-line ART treatment failure.

Viral Persistence in the Gut-Associated Lymphoid Tissue and Barriers to HIV Cure

More than 40 years after the first reported cases of what then became known as acquired immunodeficiency syndrome (AIDS), tremendous progress has been achieved in transforming the disease from almost universally fatal to a chronic manageable condition. Nonetheless, the efforts to find a preventative vaccine or a cure for the underlying infection with Human Immunodeficiency Virus (HIV) remain largely unsuccessful. Many challenges intrinsic to the virus characteristics and host response need to be overcome for either goal to be achieved. This article will review the obstacles to an effective HIV cure, specifically the steps involved in the generation of HIV latency, focusing on the role of the gut-associated lymphoid tissue, which has received less attention compared with the peripheral blood, despite being the largest repository of lymphoid tissue in the human body, and a large site for HIV persistence.

HIV Infection: Shaping the Complex, Dynamic, and Interconnected Network of the Cytoskeleton

HIV-1 has evolved a plethora of strategies to overcome the cytoskeletal barrier (i.e., actin and intermediate filaments (AFs and IFs) and microtubules (MTs)) to achieve the viral cycle. HIV-1 modifies cytoskeletal organization and dynamics by acting on associated adaptors and molecular motors to productively fuse, enter, and infect cells and then traffic to the cell surface, where virions assemble and are released to spread infection. The HIV-1 envelope (Env) initiates the cycle by binding to and signaling through its main cell surface receptors (CD4/CCR5/CXCR4) to shape the cytoskeleton for fusion pore formation, which permits viral core entry. Then, the HIV-1 capsid is transported to the nucleus associated with cytoskeleton tracks under the control of specific adaptors/molecular motors, as well as HIV-1 accessory proteins. Furthermore, HIV-1 drives the late stages of the viral cycle by regulating cytoskeleton dynamics to assure viral Pr55Gag expression and transport to the cell surface, where it assembles and buds to mature infectious virions. In this review, we therefore analyze how HIV-1 generates a cell-permissive state to infection by regulating the cytoskeleton and associated factors. Likewise, we discuss the relevance of this knowledge to understand HIV-1 infection and pathogenesis in patients and to develop therapeutic strategies to battle HIV-1.

Profound phenotypic and epigenetic heterogeneity of the HIV-1-infected CD4+ T cell reservoir

Understanding the complexity of the long-lived HIV reservoir during antiretroviral therapy (ART) remains a considerable impediment in research towards a cure for HIV. To address this, we developed a single-cell strategy to precisely define the unperturbed peripheral blood HIV-infected memory CD4+ T cell reservoir from ART-treated people living with HIV (ART-PLWH) via the presence of integrated accessible proviral DNA in concert with epigenetic and cell surface protein profiling. We identified profound reservoir heterogeneity within and between ART-PLWH, characterized by new and known surface markers within total and individual memory CD4+ T cell subsets. We further uncovered new epigenetic profiles and transcription factor motifs enriched in HIV-infected cells that suggest infected cells with accessible provirus, irrespective of reservoir distribution, are poised for reactivation during ART treatment. Together, our findings reveal the extensive inter- and intrapersonal cellular heterogeneity of the HIV reservoir, and establish an initial multiomic atlas to develop targeted reservoir elimination strategies.

Current strategies to induce selective killing of HIV-1-infected cells

Although combination antiretroviral therapy (ART) has led to significant HIV-1 suppression and improvement in immune function, persistent viral reservoirs remain that are refractory to intensified ART. ART poses many challenges such as adherence to drug regimens, the emergence of resistant virus, and cumulative toxicity resulting from long-term therapy. Moreover, latent HIV-1 reservoir cells can be stochastically activated to produce viral particles despite effective ART and contribute to the rapid viral rebound that typically occurs within 2 weeks of ART interruption; thus, lifelong ART is required for continued viral suppression. Several strategies have been proposed to address the HIV-1 reservoir such as reactivation of HIV-1 transcription using latency reactivating agents with a combination of ART, host immune clearance and HIV-1-cytotoxicity to purge the infected cells-a "shock and kill" strategy. However, these approaches do not take into account the multiple transcriptional and translational blocks that contribute to HIV-1 latency or the complex heterogeneity of the HIV-1 reservoir, and clinical trials have thus far failed to produce the desired results. Here, we describe alternative strategies being pursued that are designed to kill selectively HIV-1-infected cells while sparing uninfected cells in the absence of enhanced humoral or adaptive immune responses.

Efficient Transendothelial Migration of Latently HIV-1-Infected Cells

A small fraction of HIV-1-infected T cells forms populations of latently infected cells when they are a naive T-cell subset or in transit to a resting memory state. Latently HIV-1-infected cells reside in lymphoid tissues and serve as viral reservoirs. However, whether they systemically recirculate in the body and re-enter the lymphoid nodes are unknown. Here, we employed two in-vitro cell coculture systems mimicking the lymphatic endothelium in lymph nodes and investigated the homing potential, specifically the transendothelial migration (TEM), of two latently HIV-1-infected cell lines (J1.1 and ACH-2). In trans-well coculture systems, J1.1 and ACH-2 showed higher TEM efficiencies than their parental uninfected and acutely infected cells. The efficiency of TEM was enhanced by the presence of stromal cells, such as HS-5 and fibroblastic reticular cells. In an in-vitro reconstituted, three-dimensional coculture system in which stromal cells are embedded in collagen matrices, J1.1 showed slightly higher TEM efficiency in the presence of HS-5. In accordance with these phenotypes, latently infected cells adhered to the endothelial cells more efficiently than uninfected cells. Together, our study showed that latently HIV-1-infected cells enhanced cell adhesion and TEM abilities, suggesting their potential for efficient homing to lymph nodes.

Tissue-specific differences in HIV DNA levels and mechanisms that govern HIV transcription in blood, gut, genital tract and liver in ART-treated women

INTRODUCTION

Sex-specific differences affect multiple aspects of HIV infection, yet few studies have quantified HIV levels in tissues from women. Since an HIV functional cure will likely require a major reduction of infected cells from most tissues, we measured total and intact HIV DNA and the HIV transcription profile in blood, gut, genital tract and liver from HIV-positive antiretroviral therapy (ART) -treated women.

METHODS

Peripheral blood mononuclear cells (PBMC) and biopsies from the gastrointestinal (ileum, colon, rectosigmoid +/- liver) and genital (ectocervix, endocervix and endometrium) tracts were collected from 6 ART-treated (HIV RNA < 200 copies/mL) women. HIV DNA (total and intact) and levels of read-through, initiated (total), 5'elongated, polyadenylated and multiply spliced HIV transcripts were measured by droplet digital PCR. Immunophenotyping of cells was performed using Cytometry by time of flight (CyTOF).

RESULTS

We detected total HIV DNA in all tissues and intact HIV DNA in blood, ileum, colon, rectosigmoid and ectocervix. Initiated HIV transcripts per provirus were higher in PBMC and endometrium than in ileum, colon, rectosigmoid, ectocervix or endocervix, and higher in the rectum than either ileum or colon. 5'Elongated HIV transcripts per provirus were comparable in PBMC and endometrium, but higher than in gut or cervical samples. Polyadenylated and multiply spliced HIV transcripts were detected in PBMC (6/6 and 3/6 individuals respectively), but rarely in the tissues.

CONCLUSIONS

These results suggest tissue-specific differences in the mechanisms that govern HIV expression, with lower HIV transcription in most tissues than blood. Therapies aimed at disrupting latency, such as latency-reversing or latency-silencing agents, will be required to penetrate into multiple tissues and target different blocks to HIV transcription.

HIV-1 tracing method of systemic viremia in vivo using an artificially mutated virus pool

The appearance of human immunodeficiency virus type 1 (HIV-1) plasma viremia is associated with progression to symptomatic disease and CD4⁺ T cell depletion. To locate the source of systemic viremia, this study employed a novel method to trace HIV-1 infection in vivo. We created JRCSFξnef, a pool of infectious HIV-1 (strain JR-CSF) with highly mutated nef gene regions by random mutagenesis PCR and infected this mutated virus pool into both Jurkat-CCR5 cells and hematopoietic stem cell-transplanted humanized mice. Infection resulted in systemic plasma viremia in humanized mice and viral RNA sequencing helped us to identify multiple lymphoid organs such as spleen, lymph nodes, and bone marrow but not peripheral blood cells as the source of systemic viremia. Our data suggest that this method could be useful for the tracing of viral trafficking in vivo.

Assessment of HIV-1 integration in tissues and subsets across infection stages

The integration of HIV DNA into the host genome contributes to lifelong infection in most individuals. Few studies have examined integration in lymphoid tissue, where HIV predominantly persists before and after antiretroviral treatment (ART). Of particular interest is whether integration site distributions differ between infection stages with paired blood and tissue comparisons. Here, we profiled HIV integration site distributions in sorted memory, tissue-resident, and/or follicular helper CD4+ T cell subsets from paired blood and lymphoid tissue samples from acute, chronic, and ART-treated individuals. We observed minor differences in the frequency of nonintronic and nondistal intergenic sites, varying with tissue and residency phenotypes during ART. Genomic and epigenetic annotations were generally similar. Clonal expansion of cells marked by identical integration sites was detected, with increased detection in chronic and ART-treated individuals. However, overlap between or within CD4+ T cell subsets or tissue compartments was only observed in 8 unique sites of the 3540 sites studied. Together, these findings suggest that shared integration sites between blood and tissue may, depending on the tissue site, be the exception rather than the rule and indicate that additional studies are necessary to fully understand the heterogeneity of tissue-sequestered HIV reservoirs.

Haemopoietic cell transplantation in patients living with HIV

Haemopoietic cell transplantation is established as a standard treatment approach for people living with HIV who have haematological malignancies with poor prognosis. Studies with autologous and allogeneic haemopoietic cell transplantation suggest that HIV status does not adversely affect outcomes, provided that there is adequate infection prophylaxis. Attention to possible drug-drug interactions is important. Allogeneic haemopoietic cell transplantation substantially reduces the long-term HIV reservoir when complete donor chimerism is established. When transplants from CCR5Δ32 homozygous donors are used, HIV cure is possible.

HIV persists throughout deep tissues with repopulation from multiple anatomical sources

BACKGROUNDUnderstanding HIV dynamics across the human body is important for cure efforts. This goal has been hampered by technical difficulties and the challenge of obtaining fresh tissues.METHODSThis observational study evaluated 6 individuals with HIV (n = 4 with viral suppression using antiretroviral [ART] therapy; n = 2 with rebound viremia after stopping ART), who provided serial blood samples before death and their bodies for rapid autopsy. HIV reservoirs were characterized by digital droplet PCR, single-genome amplification, and sequencing of full-length (FL) envelope HIV. Phylogeographic methods were used to reconstruct HIV spread, and generalized linear models were tested for viral factors associated with dispersal.RESULTSAcross participants, HIV DNA levels varied from approximately 0 to 659 copies/106 cells (IQR: 22.9-126.5). A total of 605 intact FL env sequences were recovered in antemortem blood cells and across 28 tissues (IQR: 5-9). Sequence analysis showed (a) the emergence of large, identical, intact HIV RNA populations in blood after cessation of therapy, which repopulated tissues throughout the body; (b) that multiple sites acted as hubs for HIV dissemination but that blood and lymphoid tissues were the main source; (c) that viral exchanges occurred within brain areas and across the blood-brain barrier; and (d) that migration was associated with low HIV divergence between sites and greater diversity at the recipient site.CONCLUSIONHIV reservoirs persisted in all deep tissues, and blood was the main source of dispersal. This may explain why eliminating HIV susceptibility in circulating T cells via bone marrow transplants allowed some individuals with HIV to experience therapy-free remission, even though deeper tissue reservoirs were not targeted.TRIAL REGISTRATIONNot applicable.FUNDINGNIH grants P01 AI31385, P30 AI036214, AI131971-01, AI120009AI036214, HD094646, AI027763, AI134295, and AI68636.

New Frontiers in Measuring and Characterizing the HIV Reservoir

A cure for HIV infection remains elusive due to the persistence of replication-competent HIV proviral DNA during suppressive antiretroviral therapy (ART). With the exception of rare elite or post-treatment controllers of viremia, withdrawal of ART invariably results in the rebound of viremia and progression of HIV disease. A thorough understanding of the reservoir is necessary to develop new strategies in order to reduce or eliminate the reservoir. However, there is significant heterogeneity in the sequence composition, genomic location, stability, and expression of the HIV reservoir both within and across individuals, and a majority of proviral sequences are replication-defective. These factors, and the low frequency of persistently infected cells in individuals on suppressive ART, make understanding the reservoir and its response to experimental reservoir reduction interventions challenging. Here, we review the characteristics of the HIV reservoir, state-of-the-art assays to measure and characterize the reservoir, and how these assays can be applied to accurately detect reductions in reservoir during efforts to develop a cure for HIV infection. In particular, we highlight recent advances in the development of direct measures of provirus, including intact proviral DNA assays and full-length HIV DNA sequencing with integration site analysis. We also focus on novel techniques to quantitate persistent and inducible HIV, including RNA sequencing and RNA/gag protein staining techniques, as well as modified viral outgrowth methods that seek to improve upon throughput, sensitivity and dynamic range.

CD8+ T-Cell Response to HIV Infection in the Era of Antiretroviral Therapy

Although the combined antiretroviral therapy (cART) has decreased the deaths associated with the immune deficiency acquired syndrome (AIDS), non-AIDS conditions have emerged as an important cause of morbidity and mortality in HIV-infected patients under suppressive cART. Since these conditions are associated with a persistent inflammatory and immune activation state, major efforts are currently made to improve the immune reconstitution. CD8⁺ T-cells are critical in the natural and cART-induced control of viral replication; however, CD8⁺ T-cells are highly affected by the persistent immune activation and exhaustion state driven by the increased antigenic and inflammatory burden during HIV infection, inducing phenotypic and functional alterations, and hampering their antiviral response. Several CD8⁺ T-cell subsets, such as interleukin-17-producing and follicular CXCR5⁺ CD8⁺ T-cells, could play a particular role during HIV infection by promoting the gut barrier integrity, and exerting viral control in lymphoid follicles, respectively. Here, we discuss the role of CD8⁺ T-cells and some of their subpopulations during HIV infection in the context of cART-induced viral suppression, focusing on current challenges and alternatives for reaching complete reconstitution of CD8⁺ T-cells antiviral function. We also address the potential usefulness of CD8⁺ T-cell features to identify patients who will reach immune reconstitution or have a higher risk for developing non-AIDS conditions. Finally, we examine the therapeutic potential of CD8⁺ T-cells for HIV cure strategies.

Sexual dimorphism in HIV-1 infection

Sex-specific differences affecting various aspects of HIV-1 infection have been reported, including differences in susceptibility to infection, course of HIV-1 disease, and establishment of viral reservoirs. Once infected, initial plasma levels of HIV-1 viremia in women are lower compared to men while the rates of progression to AIDS are similar. Factors contributing to these sex differences are poorly understood, and range from anatomical differences and differential expression of sex hormones to differences in immune responses, the microbiome and socio-economic discrepancies, all of which may impact HIV-1 acquisition and disease progression. Ongoing research efforts aiming at controlling HIV-1 disease or reducing viral reservoirs need to take these sex-based differences in HIV-1 pathogenesis into account. In this review, we discuss established knowledge and recent findings on immune pathways leading to sex differences in HIV-1 disease manifestations, with focus on HIV-1 latency and the effect of female sex hormones on HIV-1.

Genetically Intact but Functionally Impaired HIV-1 Env Glycoproteins in the T-Cell Reservoir

HIV-infected subjects under antiretroviral treatment (ART) harbor a persistent viral reservoir in resting CD4⁺ T cells, which accounts for the resurgence of HIV replication after ART interruption. A large majority of HIV reservoir genomes are genetically defective, but even among intact proviruses few seem able to generate infectious virus. To understand this phenomenon, we examined the function and expression of HIV envelope glycoproteins reactivated from the reservoir of four HIV-infected subjects under suppressive ART. We studied full-length genetically intact env sequences from both replicative viruses and cell-associated mRNAs. We found that these Env proteins varied extensively in fusogenicity and infectivity, with strongest functional defects found in Envs from cell-associated mRNAs. Env functional impairments were essentially explained by defects in Env protein expression. Our results support the idea that defects in HIV Env expression, preventing cytopathic or immune HIV clearance, contribute to the persistence of the HIV T-cell reservoir in vivoIMPORTANCE In most individuals, evolution of HIV infection is efficiently controlled on the long-term by combination antiviral therapies. These treatments, however, fail to eradicate HIV from the infected subjects, a failure that results both in resurgence of virus replication and in resumption of HIV pathogenicity when the treatment is stopped. HIV resurgence, in these instances, is widely assumed to emerge from a reservoir of silent virus integrated in the genomes of a small number of T lymphocytes. The silent HIV reservoir is mostly composed of heavily deleted or mutated HIV DNA. Moreover, among the seemingly intact remaining HIV, only very few are actually able to efficiently propagate in tissue culture. In this study, we find that intact HIV in the reservoir often carry strong defects in their capacity to promote fusion to neighboring cells and infection of target cells, a defect related to the function and expression of the HIV envelope glycoprotein. Impaired envelope glycoprotein expression and function could explain why cells harboring these viruses tend to remain undetected and unharmed in the reservoir.

From in silico hit to long-acting late-stage preclinical candidate to combat HIV-1 infection

The HIV-1 pandemic affecting over 37 million people worldwide continues, with nearly one-half of the infected population on highly active antiretroviral therapy (HAART). Major therapeutic challenges remain because of the emergence of drug-resistant HIV-1 strains, limitations because of safety and toxicity with current HIV-1 drugs, and patient compliance for lifelong, daily treatment regimens. Nonnucleoside reverse transcriptase inhibitors (NNRTIs) that target the viral polymerase have been a key component of the current HIV-1 combination drug regimens; however, these issues hamper them. Thus, the development of novel more effective NNRTIs as anti-HIV-1 agents with fewer long-term liabilities, efficacy on new drug-resistant HIV-1 strains, and less frequent dosing is crucial. Using a computational and structure-based design strategy to guide lead optimization, a 5 µM virtual screening hit was transformed to a series of very potent nanomolar to picomolar catechol diethers. One representative, compound I, was shown to have nanomolar activity in HIV-1-infected T cells, potency on clinically relevant HIV-1 drug-resistant strains, lack of cytotoxicity and off-target effects, and excellent in vivo pharmacokinetic behavior. In this report, we show the feasibility of compound I as a late-stage preclinical candidate by establishing synergistic antiviral activity with existing HIV-1 drugs and clinical candidates and efficacy in HIV-1-infected humanized [human peripheral blood lymphocyte (Hu-PBL)] mice by completely suppressing viral loads and preventing human CD4⁺ T-cell loss. Moreover, a long-acting nanoformulation of compound I [compound I nanoparticle (compound I-NP)] in poly(lactide-coglycolide) (PLGA) was developed that shows sustained maintenance of plasma drug concentrations and drug efficacy for almost 3 weeks after a single dose.

Time course of cellular HIV-DNA and low-level HIV viremia in HIV-HCV co-infected patients whose HCV infection had been successfully treated with directly acting antivirals

This longitudinal study described cellular HIV-DNA changes and their correlation with HIV low-level plasma viremia (LLV) in HIV-HCV co-infected patients on successful antiretroviral and anti-HCV therapy by treatment with direct-acting antivirals (DAA). Thirty-nine patients were examined prior to the start of DAA (T0), after week 12 (T1) and 24 weeks (T2) of anti-HCV therapy. Cellular PBMC HIV-DNA was analysed as an absolute value and as the percentage of increase or decrease from T0 to T2. Patients were classified as having undetectable plasma HIV viraemia (UV) or LLV in the year before the start of anti-HCV treatment and within the T0-T2 study period. Thirty-five patients (89.7%) of the 39 subjects enrolled had the same plasma HIV viraemia control in the year before HCV treatment and in the T0-T2 interval. The HIV-DNA value at T0 and at T2 was higher in patients with LLV than in subjects with UV (p = 0.015 and p = 0.014, respectively). A similar proportion of patients with LLV and UV experienced an increase or decrease of HIV-DNA from T0 to T2. The percentage increase in HIV-DNA value (262.8%) from T0 to T2 was higher compared to the decrease (43.5%) in patients with UV (p = 0.012), and it was higher compared to the percentage increase in HIV-DNA value reported in subjects with LLV (262.8 versus 49%, p = 0.026). HIV-HCV co-infected patients experienced a multifaceted perturbation of cellular HIV-DNA levels within a 24-week period during anti-HCV treatment; the extent of the phenomenon was greater in subjects with UV. Fast HCV-RNA clearance seemed to have a greater influence on the cellular reservoir than on plasma HIV-RNA.

Tissue reservoirs of HIV

PURPOSE OF REVIEW

Tissue reservoirs of HIV may promote the persistent immunopathology responsible for non-AIDS morbidity and data support multifocal reactivation from tissues as the source of viral rebound during antiretroviral therapy (ART) interruption. The heterogeneity of tissue reservoirs and incomplete knowledge about their composition are obstacles to an HIV cure.

RECENT FINDINGS

In addition to the higher concentration of infected CD4 T cells found in both central lymphoid tissues and gut, specific subsets of CD4 T cells appear to play a disproportionate role in HIV persistence. Recently, a subset of central memory T cells enriched in lymph node germinal centers called T-follicular helper cells has been identified that expresses more viral RNA and occupies an anatomic niche inaccessible to cytotoxic T lymphocyte killing. Additional observations suggest that antiretroviral drug (ARV) concentrations may be lower in some tissues, raising the possibility for localized, low-level viral replication. Finally, some recent data implicate the persistence of infected, non-CD4 T-cell types in tissues during ART.

SUMMARY

The retention of infected cells in a wide variety of tissues, often with distinct viral and cellular characteristics, underscores the importance of studying tissue reservoirs in the development and assessment of cure strategies. Both inhibitory ARVs and latency-reversing drugs must reach these sites, and novel strategies may be needed to attack virus in cells as variable as T-follicular helper cells and macrophages.

Perspectives on Human Immunodeficiency Virus (HIV) Cure: HIV Persistence in Tissue

The uneven anatomic distribution of cell subsets that harbor human immunodeficiency virus (HIV) during antiretroviral therapy (ART) complicates investigation of the barriers to HIV cure. Here we propose that while previous studies done largely in blood cells have led to important investigations into HIV latency, other important mechanisms of HIV persistence during ART may not be readily apparent in the bloodstream. We specifically consider as an example the question of ongoing HIV replication during ART. We discuss how growing understanding of key anatomic sanctuaries for the virus can inform future experiments aimed at further clarifying this issue.

HIV RNA and proviral HIV DNA can be detected in semen after 6 months of antiretroviral therapy although HIV RNA is undetectable in blood

The risk of sexual transmission of HIV is strongly correlated with amounts of genital HIV RNA. Few studies have reported amounts of HIV RNA and HIV DNA in semen in HIV-infected Chinese patients undergoing antiviral treatment (ART). In this observational study, the amounts of HIV RNA and HIV DNA in semen were assessed after six months of ART in HIV-infected Chinese individuals, when HIV RNA was undetectable in blood . This study included 19 HIV-infected Chinese men undergoing ART for six months. Amounts of HIV in paired semen and blood samples were assessed using real-time PCR. The C2-V5 region of the HIV envelope (env) genes was cloned and sequenced and genotype and co-receptor usage predicted based on the sequence. It was found that HIV RNA was undetectable in the plasma of most patients (17/19), whereas HIV RNA could be detected in the semen of most patients (16/19). HIV DNA could be detected in both semen and blood. Genetic diversity of HIV between the seminal and blood compartments was identified. Thus, amounts of HIV RNA and HIV DNA remain high in semen of HIV-infected Chinese patients after six months of ART treatment, even when HIV RNA was undetectable in blood.

Development of real-time PCR for quantitation of simian immunodeficiency virus 2-LTR circles

BACKGROUND

Non-human primates infected with simian immunodeficiency virus (SIV) represent a robust model to evaluate pre-clinical efficacy of HIV-1 preventive strategies and to determine the size of reservoir.

METHODS

We developed a real-time qPCR assay to specifically quantify episomal 2-LTR circular DNA in peripheral blood mononuclear cells and brain tissues from SIV-infected macaques.

RESULTS

This assay has sensitivity, accuracy and reproducibility over seven orders of magnitude. High copy numbers of SIV 2-LTR circles were correlated to high proviral DNA levels in brains of two SIV encephalitic animals. In contrast, no 2-LTR circles were detectable in two SIV-infected animals with no sign of encephalitis or two animals that had mild encephalitis with low levels of proviral DNA.

CONCLUSIONS

These results suggest that simultaneous application of total proviral DNA and 2-LTR circle assays provides quantitative evaluation of pathogenesis and outcome of SIV infection in macaques.

Nanodrug formulations to enhance HIV drug exposure in lymphoid tissues and cells: clinical significance and potential impact on treatment and eradication of HIV/AIDS

Although oral combination antiretroviral therapy effectively clears plasma HIV, patients on oral drugs exhibit much lower drug concentrations in lymph nodes than blood. This drug insufficiency is linked to residual HIV in cells of lymph nodes. While nanoformulations improve drug solubility, safety and delivery, most HIV nanoformulations are intended to extend plasma levels. A stable nanodrug combination that transports, delivers and accumulates in lymph nodes is needed to clear HIV in lymphoid tissues. This review discusses limitations of current oral combination antiretroviral therapy and advances in anti-HIV nanoformulations. A 'systems approach' has been proposed to overcome these limitations. This concept has been used to develop nanoformulations for overcoming drug insufficiency, extending cell and tissue exposure and clearing virus for treating HIV/AIDS.

Barriers to a cure for HIV in women

Introduction

Distinct biological factors exist that affect the natural history of HIV and the host immune response between women and men. These differences must be addressed to permit the optimal design of effective HIV eradication strategies for much of the HIV-positive population.

Methods and results

Here, we review the literature on sex-based differences in HIV pathogenesis and natural history in tissues and anatomic compartments, HIV latency and transcriptional activity, and host immunity including the role of sex hormones. We then outline the potential effects of these differences on HIV persistence, and on the safety and efficacy of HIV eradication and curative interventions. Finally, we discuss the next steps necessary to elucidate these factors to achieve a cure for HIV, taking in account the complex ethical issues and the regulatory landscape in the hopes of stimulating further research and awareness in these areas.

Conclusions

Targeted enrolment of women in clinical trials and careful sex-based analysis will be crucial to gain further insights into sex-based differences in HIV persistence and to design sex-specific approaches to HIV eradication, if required.

HIV Replication at Low Copy Number and its Correlation with the HIV Reservoir: A Clinical Perspective

The efficacy of combination therapy (antiretroviral therapy - ARV) is demonstrated by the high rates of viral suppression achieved in most treated HIV patients. Whereas contemporary treatments may continuously suppress HIV replication, they do not eliminate the latent reservoir, which can reactivate HIV infection if ARV is discontinued. The persistence of HIV proviral DNA and infectious viruses in CD4+ T cells and others cells has long been considered a major obstacle in eradicating the HIV virus in treated patients. Moreover, recent studies have demonstrated the persistence of HIV replication at low copies in most patients on suppressive ARV. The source of this ‘residual viraemia’ and whether it declines over years of therapy remain unknown. Similarly, little is known regarding the biological relationships between the HIV reservoir and viral replication at low copies. The question of whether this ‘residual viraemia’ represents active replication or the release of non-productive virus from the reservoir has not been adequately resolved.

From a clinical perspective, both the quantification of the HIV reservoir and the detection of low levels of replication in full-responder patients on prolonged ARV may provide important information regarding the effectiveness of treatment and the eradication of HIV. To date, the monitoring of these two parameters has been conducted only for research purposes; the routine use of standardised tests procedure is lacking. This review aims to assess the current data regarding the correlation between HIV replication at low copies and the HIV reservoir and to provide useful information for clinicians.

FRET-based assay to screen inhibitors of HIV-1 reverse transcriptase and nucleocapsid protein

During HIV-1 reverse transcription, the single-stranded RNA genome is converted into proviral double stranded DNA by Reverse Transcriptase (RT) within a reverse transcription complex composed of the genomic RNA and a number of HIV-1 encoded proteins, including the nucleocapsid protein NCp7. Here, we developed a one-step and one-pot RT polymerization assay. In this in vitro assay, RT polymerization is monitored in real-time by Förster resonance energy transfer (FRET) using a commercially available doubly-labeled primer/template DNA. The assay can monitor and quantify RT polymerization activity as well as its promotion by NCp7. Z-factor values as high as 0.89 were obtained, indicating that the assay is suitable for high-throughput drug screening. Using Nevirapine and AZT as prototypical RT inhibitors, reliable IC50 values were obtained from the changes in the RT polymerization kinetics. Interestingly, the assay can also detect NCp7 inhibitors, making it suitable for high-throughput screening of drugs targeting RT, NCp7 or simultaneously, both proteins.

Anti-HIV drug-combination nanoparticles enhance plasma drug exposure duration as well as triple-drug combination levels in cells within lymph nodes and blood in primates

HIV patients on combination oral drug therapy experience insufficient drug levels in lymph nodes, which is linked to viral persistence. Following success in enhancing lymph node drug levels and extending plasma residence time of indinavir formulated in lipid nanoparticles, we developed multidrug anti-HIV lipid nanoparticles (anti-HIV LNPs) containing lopinavir (LPV), ritonavir (RTV), and tenofovir (PMPA). These anti-HIV LNPs were prepared, characterized, scaled up, and evaluated in primates with a focus on plasma time course and intracellular drug exposure in blood and lymph nodes. Four macaques were subcutaneously administered anti-HIV LNPs and free drug suspension in a crossover study. The time course of the plasma drug concentration as well as intracellular drug concentrations in blood and inguinal lymph nodes were analyzed to compare the effects of LNP formulation. Anti-HIV LNPs incorporated LPV and RTV with high efficiency and entrapped a reproducible fraction of hydrophilic PMPA. In primates, anti-HIV LNPs produced over 50-fold higher intracellular concentrations of LPV and RTV in lymph nodes compared to free drug. Plasma and intracellular drug levels in blood were enhanced and sustained up to 7 days, beyond that achievable by their free drug counterpart. Thus, multiple antiretroviral agents can be simultaneously incorporated into anti-HIV lipid nanoparticles to enhance intracellular drug concentrations in blood and lymph nodes, where viral replication persists. As these anti-HIV lipid nanoparticles also prolonged plasma drug exposure, they hold promise as a long-acting dosage form for HIV patients in addressing residual virus in cells and tissue.

Long-acting three-drug combination anti-HIV nanoparticles enhance drug exposure in primate plasma and cells within lymph nodes and blood

Insufficient HIV drug levels in lymph nodes have been linked to viral persistence. To overcome lymphatic drug insufficiency, we developed and evaluated in primates a lipid-drug nanoparticle containing lopinavir, ritonavir, and tenofovir. These nanoparticles produced over 50-fold higher intracellular lopinavir, ritonavir and tenofovir concentrations in lymph nodes compared to free drug. Plasma and intracellular drug levels in blood were enhanced and sustained for 7 days after a single subcutaneous dose, exceeding that achievable with current oral therapy.

Cellular HIV reservoir replenishment is not affected by blip or intermittent viremia episodes during darunavir/ritonavir monotherapy

OBJECTIVE

To assess the impact of blips and persistent viremia episodes on cell-associated HIV-DNA reservoir in extensively pretreated patients receiving ritonavir-boosted darunavir monotherapy (MtDRV/rtv) for 24 months.

DESIGN AND METHODS

Patients from the MonDAR prospective study (NCT01606722) who received at least 6 months of MtDRV/rtv and had at least two available peripheral blood mononuclear cells (PBMCs) samples were selected and classified according to the viral outcome as continuous undetectable viremia (cUV; n = 40), blips (n = 31), intermittent viremia (IV; n = 23), and virological failure (VF, two consecutive viral loads >200 copies/ml; n = 20). Proviral HIV-DNA was quantified by real-time PCR in PBMCs samples at baseline, and months 6, 12, 18 and 24. Additionally, HIV-DNA levels were exhaustively analyzed at virological failure and blip episodes.

RESULTS

The HIV-DNA levels remained constant during the 24 months in every group. Neither blips nor intermittent viremia influenced the HIV-DNA levels at short-term or at middle term. By contrast, virological failure episodes gave rise to a significant increase in proviral DNA (2.15 vs. 2.32 log10 HIV-DNA copies/10 PBMCs; P = 0.042). Basal proviral DNA levels more than 2 log10 copies/10 PBMCs predicted the time to viral rebound at any given cut-off point (>20, >50, and >200 copies/ml. HR: 3.02, 2.61, and 3.02, respectively; P ≤ 0.03. Besides, an adherence less than 95% was also strongly associated with virological failure (HR, 3.17; P = 0.021).

CONCLUSION

Blip episodes and intermittent viremia did not affect the cellular HIV reservoir dynamic during MtDRV/rtv. Higher adherence and an HIV-DNA levels less than 2 log10 copies/10 PBMCs at baseline were associated with a lower risk of virological failure.

Emerging research and clinical development trends of liposome and lipid nanoparticle drug delivery systems

Liposomes are spherical-enclosed membrane vesicles mainly constructed with lipids. Lipid nanoparticles are loaded with therapeutics and may not contain an enclosed bilayer. The majority of those clinically approved have diameters of 50-300 nm. The growing interest in nanomedicine has fueled lipid-drug and lipid-protein studies, which provide a foundation for developing lipid particles that improve drug potency and reduce off-target effects. Integrating advances in lipid membrane research has enabled therapeutic development. At present, about 600 clinical trials involve lipid particle drug delivery systems. Greater understanding of pharmacokinetics, biodistribution, and disposition of lipid-drug particles facilitated particle surface hydration technology (with polyethylene glycol) to reduce rapid clearance and provide sufficient blood circulation time for drug to reach target tissues and cells. Surface hydration enabled the liposome-encapsulated cancer drug doxorubicin (Doxil) to gain clinical approval in 1995. Fifteen lipidic therapeutics are now clinically approved. Although much research involves attaching lipid particles to ligands selective for occult cells and tissues, preparation procedures are often complex and pose scale-up challenges. With emerging knowledge in drug target and lipid-drug distribution in the body, a systems approach that integrates knowledge to design and scale lipid-drug particles may further advance translation of these systems to improve therapeutic safety and efficacy.

Delayed HIV-1 Infection of CD4+T Lymphocytes from Therapy-Naïve Patients Demonstrated by Quantification of HIV-1 DNA Copy Numbers

Measuring the amount of HIV-1 DNA in infected cells is important to estimate the size of the viral reservoir in patients. However, the clinical impact of the intracellular viral DNA level remains unclear. The present study examines the clinical significance of the HIV-1 DNA level in peripheral CD4+ T lymphocytes from 21 therapy-naïve patients. HIV-1 DNA levels in purified peripheral CD4+ T lymphocytes were measured by the real-time PCR method using the Roche LightCycler system that can detect 200 copies/10(6) cells. We detected intracellular HIV-1 DNA in 15 (71.4%) of 21 patients at levels ranging from 270 to 98,120 copies/10(6) CD4+ cells, with a median of 2,220 copies/10(6) cells. We also found HIV-1 DNA that was below the detection limit in the remaining 6 patients, although 8,800-150,000 copies/ml of HIV-1 RNA were detected in plasma. Circular HIV-1 DNA was not detected in 5 of 6 cases, suggesting that reverse transcription in CD4+ T lymphocytes of these cases was not active. Thus, delayed HIV-1 infection of CD4+ T lymphocytes was demonstrated in these patients. The level of HIV-1 DNA in peripheral CD4+ T lymphocytes indicates the clinical status of therapy-naïve patients.

The distribution of HIV DNA and RNA in cell subsets differs in gut and blood of HIV-positive patients on ART: implications for viral persistence

Even with optimal antiretroviral therapy, human immunodeficiency virus (HIV) persists in plasma, blood cells, and tissues. To develop new therapies, it is essential to know what cell types harbor residual HIV. We measured levels of HIV DNA, RNA, and RNA/DNA ratios in sorted subsets of CD4+ T cells (CCR7+, transitional memory, and effector memory) and non-CD4+ T leukocytes from blood, ileum, and rectum of 8 ART-suppressed HIV-positive subjects. Levels of HIV DNA/million cells in CCR7+ and effector memory cells were higher in the ileum than blood. When normalized by cell frequencies, most HIV DNA and RNA in the blood were found in CCR7+ cells, whereas in both gut sites, most HIV DNA and RNA were found in effector memory cells. HIV DNA and RNA were observed in non-CD4+ T leukocytes at low levels, particularly in gut tissues. Compared to the blood, the ileum had higher levels of HIV DNA and RNA in both CD4+ T cells and non-CD4+ T leukocytes, whereas the rectum had higher HIV DNA levels in both cell types but lower RNA levels in CD4+ T cells. Future studies should determine whether different mechanisms allow HIV to persist in these distinct reservoirs, and the degree to which different therapies can affect each reservoir.

Biodegradable core-shell carriers for simultaneous encapsulation of synergistic actives

Simultaneous encapsulation of multiple active substances in a single carrier is essential for therapeutic applications of synergistic combinations of drugs. However, traditional carrier systems often lack efficient encapsulation and release of incorporated substances, particularly when combinations of drugs must be released in concentrations of a prescribed ratio. We present a novel biodegradable core-shell carrier system fabricated in a one-step, solvent-free process on a microfluidic chip; a hydrophilic active (doxorubicin hydrochloride) is encapsulated in the aqueous core, while a hydrophobic active (paclitaxel) is encapsulated in the solid shell. Particle size and composition can be precisely controlled, and core and shell can be individually loaded with very high efficiency. Drug-loaded particles can be dried and stored as a powder. We demonstrate the efficacy of this system through the simultaneous encapsulation and controlled release of two synergistic anticancer drugs using two cancer-derived cell lines. This solvent-free platform technology is also of high potential value for encapsulation of other active ingredients and chemical reagents.

Challenges in detecting HIV persistence during potentially curative interventions: a study of the Berlin patient

There is intense interest in developing curative interventions for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV-infected adult who has exhibited evidence of cure after allogeneic hematopoietic stem cell transplant from a homozygous CCR5Δ32 donor. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV DNA or RNA was detected in peripheral blood mononuclear cells (PBMC), spinal fluid, lymph node, or terminal ileum, and no replication-competent virus could be cultured from PBMCs. However, HIV RNA was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in ART-suppressed patients. It was not possible to obtain sequence data from plasma or gut, while an X4 sequence from PBMC did not match the pre-transplant sequence. HIV antibody levels were readily detectable but declined over time; T cell responses were largely absent. The occasional, low-level PCR signals raise the possibility that some HIV nucleic acid might persist, although they could also be false positives. Since HIV levels in well-treated individuals are near the limits of detection of current assays, more sensitive assays need to be developed and validated. The absence of recrudescent HIV replication and waning HIV-specific immune responses five years after withdrawal of treatment provide proof of a clinical cure.

There is intense interest in developing a cure for HIV. How such a cure will be quantified and defined is not known. We applied a series of measurements of HIV persistence to the study of an HIV+ adult who has exhibited evidence of cure after a stem cell transplant. Samples from blood, spinal fluid, lymph node, and gut were analyzed in multiple laboratories using different approaches. No HIV was detected in blood cells, spinal fluid, lymph node, or small intestine, and no infectious virus was recovered from blood. However, HIV was detected in plasma (2 laboratories) and HIV DNA was detected in the rectum (1 laboratory) at levels considerably lower than those expected in antiretroviral treated patients. The occasional, low-level HIV signals might be due to persistent HIV or might reflect false positives. The sensitivity of the current generation of assays to detect HIV RNA, HIV DNA, and infectious virus are close to the limits of detection. Improvements in these tests will be needed for future curative studies. The lack of rebounding virus after five years without therapy, the failure to isolate infectious virus, and the waning HIV-specific immune responses all indicate that the Berlin Patient has been effectively cured.

Cell-associated HIV RNA: a dynamic biomarker of viral persistence

In most HIV-infected individuals adherent to modern antiretroviral therapy (ART), plasma viremia stays undetectable by clinical assays and therefore, additional virological markers for monitoring and predicting therapy responses and for measuring the degree of HIV persistence in patients on ART should be identified. For the above purposes, quantitation of cell-associated HIV biomarkers could provide a useful alternative to measurements of viral RNA in plasma. This review concentrates on cell-associated (CA) HIV RNA with the emphasis on its use as a virological biomarker. We discuss the significance of CA HIV RNA as a prognostic marker of disease progression in untreated patients and as an indicator of residual virus replication and the size of the dynamic viral reservoir in ART-treated patients. Potential value of this biomarker for monitoring the response to ART and to novel HIV eradication therapies is highlighted.

Enhanced anti-HIV efficacy of indinavir after inclusion in CD4-targeted lipid nanoparticles

BACKGROUND

Combination drug therapy has reduced plasma HIV to undetectable levels; however, drug-sensitive virus persists in patients' lymphoid tissue. We have reported significant lymphoid tissue drug localization with indinavir-associated lipid nanoparticles (LNPs). Our current objective is to evaluate whether additional enhancement is achievable by targeting these particles to CD4-HIV host cells.

METHODS

We characterized 2 peptide-coated (CD4-BP2 and CD4-BP4) drug-associated LNPs and demonstrated CD4-cell specificity. Drug-associated LNPs expressing polyethyleneglycol were exposed on HIV-2-infected cells under dynamic conditions that emulated lymph node physiology for 15, 30, and 60 minutes at concentrations from 0 to 25 μM and evaluated for antiviral activity and cell-associated drug concentrations. The specificity of CD4-mediated enhancement of indinavir LNPs antiviral activity was evaluated by blocking with anti-CD4 antibody.

RESULTS

Inclusion of CD4-binding peptides on LNPs enhanced antiviral activity for all incubation conditions, compared with control particles or soluble drug (eg, 60 minutes exposure, EC50 = 0.12-0.13 vs. 0.46 μM for targeted nanoparticles vs. soluble drug). The CD4-BP4 peptide exhibited higher efficiency in eliciting antiviral activity than CD4-BP2-coated particles (EC50 = 7.5 μM vs. >25 μM at 15 minutes drug exposure). This enhancement seems to be driven by CD4 availability and cell-associated indinavir concentrations, as blocking of CD4 significantly ablated indinavir efficacy in targeted particles and indinavir concentrations reflected the observed anti-HIV activity.

CONCLUSIONS

We constructed CD4-targeted LNPs that provide selective binding and efficient delivery of indinavir to CD4-HIV host cells. Inclusion of polyethyleneglycol in LNPs would minimize immune recognition of peptides. The enhancement of anti-HIV effects is effective even under limited time exposure.

Design and characterization of novel peptide-coated lipid nanoparticles for targeting anti-HIV drug to CD4 expressing cells

Human immunodeficiency virus (HIV) persists in lymph nodes and lymphoid tissues even during aggressive drug treatment, likely due to insufficient drug concentrations at this site. Therefore, to eliminate this residual virus, methods that enhance lymph node drug concentrations are currently being evaluated. Although enhanced drug concentrations in tissue have been achieved with drug-associated lipid nanoparticles, targeting these particles to CD4(+) cells may provide specific delivery of drug to HIV target cells and further enhance drug efficacy. We have evaluated four candidate peptides with reported binding specificity to CD4 for anchoring on lipid nanoparticle preparations previously shown to localize in lymph nodes. Terminal cysteine containing candidate peptides were conjugated to lipid nanoparticles through maleimide-linked phospholipids for targeting to CD4 cells. Using fluorescently labeled lipid nanoparticle binding to cells with varying degree of CD4 expression (CEMx174, Molt-4, Jurkat, and Ramos), we indentified two peptide sequences that provided CD4 selectivity to nanoparticles. These two peptide candidates on lipid nanoparticles bound to cells corresponding to the degree of CD4 expression and in a peptide dose dependent manner. Further, binding of these targeted lipid nanoparticles was CD4 specific, as pre-exposure of CD4(+) cells to anti-CD4 antibodies or free peptides inhibited the binding interactions. These results indicate targeting of lipid nanoparticles for specific binding to CD4 can be accomplished by tagging CD4 binding peptides with peptides, and these results provide a basis for further evaluation of this targeted delivery system to enhance antiviral drug delivery to CD4(+) HIV host cells, particularly those in lymph nodes and lymphoid tissues.

Absence of HIV-1 evolution in the gut-associated lymphoid tissue from patients on combination antiviral therapy initiated during primary infection

Mucosal mononuclear (MMC) CCR5+CD4+ T cells of the gastrointestinal (GI) tract are selectively infected and depleted during acute HIV-1 infection. Despite early initiation of combination antiretroviral therapy (cART), gut-associated lymphoid tissue (GALT) CD4+ T cell depletion and activation persist in the majority of HIV-1 positive individuals studied. This may result from ongoing HIV-1 replication and T-cell activation despite effective cART. We hypothesized that ongoing viral replication in the GI tract during cART would result in measurable viral evolution, with divergent populations emerging over time. Subjects treated during early HIV-1 infection underwent phlebotomy and flexible sigmoidoscopy with biopsies prior to and 15–24 months post initiation of cART. At the 2^nd biopsy, three GALT phenotypes were noted, characterized by high, intermediate and low levels of immune activation. A representative case from each phenotype was analyzed. Each subject had plasma HIV-1 RNA levels <50 copies/ml at 2^nd GI biopsy and CD4+ T cell reconstitution in the peripheral blood. Single genome amplification of full-length HIV-1 envelope was performed for each subject pre- and post-initiation of cART in GALT and PBMC. A total of 280 confirmed single genome sequences (SGS) were analyzed for experimental cases. For each subject, maximum likelihood phylogenetic trees derived from molecular sequence data showed no evidence of evolved forms in the GALT over the study period. During treatment, HIV-1 envelope diversity in GALT-derived SGS did not increase and post-treatment GALT-derived SGS showed no substantial genetic divergence from pre-treatment sequences within transmitted groups. Similar results were obtained from PBMC-derived SGS. Our results reveal that initiation of cART during acute/early HIV-1 infection can result in the interruption of measurable viral evolution in the GALT, suggesting the absence of de-novo rounds of HIV-1 replication in this compartment during suppressive cART.

This study was undertaken to determine if the gastrointestinal tract is a site of ongoing viral replication during suppressive combination antiretroviral therapy (cART) (defined by plasma HIV-1 RNA levels below 50 copies/ml). We found no evidence of substantial viral evolution in HIV-1 envelope sequences derived from peripheral blood mononuclear cells or cells of the gastrointestinal tract lymphoid tissue in participants initiating cART during early HIV-1 infection. To our knowledge, this is the first application of the single genome amplification technique to the comparative analysis of HIV-1 quasi-species derived from the gastrointestinal tract, demonstrating that in these individuals, cART has the ability to halt measurable evolution of HIV-1 envelope in this compartment. These findings suggest the absence of de-novo rounds of HIV-1 replication during suppressive cART and by extension, that experimentally observed, persistently elevated levels of immune activation in the gastrointestinal lymphoid tissue seen after the early initiation and uninterrupted use of cART (despite relative immune reconstitution in the blood) is likely due to factors other than ongoing viral replication. This implies that in this virally suppressed population, cART intensification is unlikely to significantly impact persistent CD4+ T cell depletion or increased levels of immune activation in the gastrointestinal tract.

Generation of HIV latency in humanized BLT mice

Here we demonstrate that a combination of tenofovir, emtricitabine, and raltegravir effectively suppresses peripheral and systemic HIV replication in humanized BLT mice. We also demonstrate that antiretroviral therapy (ART)-treated humanized BLT mice harbor latently infected resting human CD4+ T cells that can be induced ex vivo to produce HIV. We observed that the levels of infected resting human CD4+ T cells present in BLT mice are within the range of those observed circulating in patients undergoing suppressive ART. These results demonstrate the potential of humanized BLT mice as an attractive model for testing the in vivo efficacy of novel HIV eradication strategies.

Rapid turnover of 2-LTR HIV-1 DNA during early stage of highly active antiretroviral therapy

Background

Despite prolonged treatment with highly active antiretroviral therapy (HAART), the infectious HIV-1 continues to replicate and resides latently in the resting memory CD4+ T lymphocytes, which blocks the eradication of HIV-1. The viral persistence of HIV-1 is mainly caused by its proviral DNA being either linear nonintegrated, circular nonintegrated, or integrated. Previous reports have largely focused on the dynamics of HIV-1 DNA from the samples collected with relatively long time intervals during the process of disease and HAART treatment, which may have missed the intricate changes during the intervals in early treatment.

Methodology/Principal Findings

In this study, we investigated the dynamics of HIV-1 DNA in patients during the early phase of HARRT treatment. Using optimized real time PCR, we observed significant changes in 2-LTR during the first 12-week of treatment, while total and integrated HIV-1 DNA remained stable. The doubling time and half-life of 2-LTR were not correlated with the baseline and the rate of changes in plasma viral load and various CD4+ T-cell populations. Longitudinal analyses on 2-LTR sequences and plasma lipopolysaccharide (LPS) levels did not reveal any significant changes in the same treatment period.

Conclusions/Significance

Our study revealed the rapid changes in 2-LTR concentration in a relatively large number of patients during the early HAART treatment. The rapid changes indicate the rapid infusion and clearance of cells bearing 2-LTR in the peripheral blood. Those changes are not expected to be caused by the blocking of viral integration, as our study did not include the integrase inhibitor raltegravir. Our study helps better understand the dynamics of HIV-DNA and its potential role as a biomarker for the diseases and for the treatment efficacy of HAART.

HIV-associated nephropathy in the setting of maximal virologic suppression

Human immunodeficiency virus (HIV)-associated nephropathy (HIVAN) is most frequently seen as a late manifestation in adult patients with a high viral load and low T-helper cell (CD4) counts. We report a case of HIVAN in a black Zimbabwean teenager in whom the disease activity was well suppressed for years following highly active antiretroviral therapy (HAART). Proteinuria was absent at 9 years of age when he presented with vertically transmitted HIV infection. Within a few months of HAART, the viral load became undetectable and CD4 count was normalised. Nephrotic range proteinuria, with preserved renal function, developed approximately 4 years later despite excellent HIV disease suppression. Renal biopsy showed non-collapsing focal segmental glomerular sclerosis changes compatible with HIVAN. Although the role of other unknown factors in the disease pathogenesis could not be totally excluded, this case demonstrates that HIVAN can still occur in HIV-infected children despite excellent HAART and that the disease manifestations and outcome may differ from those reported in previous studies.

Proteomic analysis of HIV-infected macrophages

Mononuclear phagocytes (monocytes, macrophages, and microglia) play an important role in innate immunity against pathogens including HIV. These cells are also important viral reservoirs in the central nervous system and secrete inflammatory mediators and toxins that affect the tissue environment and function of surrounding cells. In the era of antiretroviral therapy, there are fewer of these inflammatory mediators. Proteomic approaches including surface enhancement laser desorption ionization, one- and two-dimensional difference in gel electrophoresis, and liquid chromatography tandem mass spectrometry have been used to uncover the proteins produced by in vitro HIV-infected monocytes, macrophages, and microglia. These approaches have advanced the understanding of novel mechanisms for HIV replication and neuronal damage. They have also been used in tissue macrophages that restrict HIV replication to understand the mechanisms of restriction for future therapies. In this review, we summarize the proteomic studies on HIV-infected mononuclear phagocytes and discuss other recent proteomic approaches that are starting to be applied to this field. As proteomic instruments and methods evolve to become more sensitive and quantitative, future studies are likely to identify more proteins that can be targeted for diagnosis or therapy and to uncover novel disease mechanisms.

Identifying HIV infection in diagnostic histopathology tissue samples--the role of HIV-1 p24 immunohistochemistry in identifying clinically unsuspected HIV infection: a 3-year analysis

AIMS

Because of the clinical difficulty in identifying the early stages of human immunodeficiency virus (HIV) infection, the histopathologist often has to consider the diagnosis of HIV in tissue samples from patients with no previous suspicion of HIV infection. The aim was to investigate the practicality and utility of routine HIV-1 p24 immunohistochemistry on tissue samples received at a London histopathology laboratory.

METHODS AND RESULTS

Over a 3-year period, HIV-1 p24 was evaluated immunohistochemically on 123 cases. Of these, 37 (30%) showed positive expression of p24 in lesional follicular dendritic cells (FDCs). Of these 37 cases, 11 were not clinically suspected to be HIV+ and had no prior serological evidence of HIV infection. These cases represented lymph node biopsies, tonsillar and nasopharyngeal biopsies and a parotid excision. In addition to expression on FDCs, in 22 cases (60%), p24 also highlighted mononuclear cells and macrophages. p24 was also useful in confirming the presence of HIV in lymphoid tissue in non-lymphoid organs such as the lung, anus, salivary gland and brain. Immunonegativity occurred in occasional known HIV+ cases, probably related to treatment or tissue processing.

CONCLUSIONS

This study confirms the usefulness of this technique in detecting unsuspected HIV infection in lymphoid and non-lymphoid organs on histopathological material and should be part of routine evaluation of lymph nodes and lymphoid tissue in other organs if morphological or clinical features suggest HIV infection.

Effect of a short-term HAART on SIV load in macaque tissues is dependent on time of initiation and antiviral diffusion

BACKGROUND

HIV reservoirs are rapidly established after infection, and the effect of HAART initiated very early during acute infection on HIV reservoirs remains poorly documented, particularly in tissue known to actively replicate the virus. In this context, we used the model of experimental infection of macaques with pathogenic SIV to assess in different tissues: (i) the effect of a short term HAART initiated at different stages during acute infection on viral dissemination and replication, and (ii) the local concentration of antiviral drugs.

RESULTS

Here, we show that early treatment with AZT/3TC/IDV initiated either within 4 hours after intravenous infection of macaques with SIVmac251 (as a post exposure prophylaxis) or before viremia peak (7 days post-infection [pi]), had a strong impact on SIV production and dissemination in all tissues but did not prevent infection. When treatment was initiated after the viremia peak (14 days pi) or during early chronic infection (150 days pi), significant viral replication persists in the peripheral lymph nodes and the spleen of treated macaques despite a strong effect of treatment on viremia and gut associated lymphoid tissues. In these animals, the level of virus persistence in tissues was inversely correlated with local concentrations of 3TC: high concentrations of 3TC were measured in the gut whereas low concentrations were observed in the secondary lymphoid tissues. IDV, like 3TC, showed much higher concentration in the colon than in the spleen. AZT concentration was below the quantification threshold in all tissues studied.

CONCLUSIONS

Our results suggest that limited antiviral drug diffusion in secondary lymphoid tissues may allow persistent viral replication in these tissues and could represent an obstacle to HIV prevention and eradication.

Antiretroviral release from poly(DL-lactide-co-glycolide) nanoparticles in mice

OBJECTIVES

Free ritonavir, lopinavir and efavirenz injected intraperitoneally were compared with antiretroviral (AR) nanoparticles (NPs).

METHODS

This is a prospective study in BALB/c mice comparing the pharmacokinetics of free drugs with AR NPs. All animals received free drugs or AR NPs (20 mg/kg) in PBS. In vitro replication assays were used for determination of the anti-HIV efficacy of NP formulations. At specific times (free drugs 0.08, 0.125, 0.25, 0.33, 1, 2 and 3 days; AR NPs 0.125, 0.33, 1, 2, 4, 7, 14, 21, 28, 35 and 42 days) mice were euthanized and serum and organs were harvested for determination of AR concentrations by HPLC. Single treatment of monocyte-derived macrophages (MDMs) infected with HIV-1(ada) compared AR NPs (0.005-0.05 mg/mL) with free efavirenz or lopinavir/ritonavir (0.01-0.1 mg/mL), blank NPs and controls. Results are presented as means ± SEM.

RESULTS

Serum free AR drug concentrations peaked 4 h post-injection (ritonavir 3.9 ± 3.05, lopinavir 3.4 ± 2.5 and efavirenz 1.8 ± 0.63 µg/mL) and were eliminated by 72 h. Poly(dl-lactide-co-glycolide) NP animals had detectable ritonavir, lopinavir and efavirenz concentrations in all tissues for 28 days. Treatment of MDMs with AR NPs resulted in sustained inhibition of HIV-1(ada) replication.

CONCLUSIONS

AR drug concentrations from NPs are sustained for 28 days in vivo and anti-HIV inhibition was comparable to that of free drugs in vitro and could be a sustained treatment for delivery of AR drugs.

HIV reservoirs in vivo and new strategies for possible eradication of HIV from the reservoir sites

Even though the treatment of human immunodeficiency virus (HIV)-infected individuals with highly active antiretroviral therapy (HAART) provides a complete control of plasma viremia to below detectable levels (<40 copies/mL plasma), there is an unequal distribution of all antiretroviral drugs across diverse cellular and anatomic compartments in vivo. The main consequence of this is the acquisition of resistance by HIV to all known classes of currently prescribed antiretroviral drugs and the establishment of HIV reservoirs in vivo. HIV has a distinct advantage of surviving in the host via both pre-and postintegration latency. The postintegration latency is caused by inert and metabolically inactive provirus, which cannot be accessed either by the immune system or the therapeutics. This integrated provirus provides HIV with a safe haven in the host where it is incessantly challenged by its immune selection pressure and also by HAART. Thus, the provirus is one of the strategies for viral concealment in the host and the provirus can be rekindled, through unknown stimuli, to create progeny for productive infection of the host. Thus, the reservoir establishment remains the biggest impediment to HIV eradication from the host. This review provides an overview of HIV reservoir sites and discusses both the virtues and problems associated with therapies/strategies targeting these reservoir sites in vivo.

Viral sanctuaries during highly active antiretroviral therapy in a nonhuman primate model for AIDS

Highly active antiretroviral therapy (HAART) enables long-term suppression of plasma HIV-1 loads in infected persons, but low-level virus persists and rebounds following cessation of therapy. During HAART, this virus resides in latently infected cells, such as resting CD4(+) T cells, and in other cell types that may support residual virus replication. Therapeutic eradication will require elimination of virus from all reservoirs. We report here a comprehensive analysis of these reservoirs in fluids, cells, and tissues in a rhesus macaque model that mimics HAART in HIV-infected humans. This nonhuman primate model uses RT-SHIV, a chimera of simian immunodeficiency virus containing the HIV-1 reverse transcriptase (RT). Methods were developed for extraction, preamplification, and real-time PCR analyses of viral DNA (vDNA) and viral RNA (vRNA) in tissues from RT-SHIV-infected macaques. These methods were used to identify viral reservoirs in RT-SHIV-infected macaques treated with a potent HAART regimen consisting of efavirenz, emtricitabine, and tenofovir. Plasma virus loads at necropsy ranged from 11 to 28 copies of vRNA per ml. Viral RNA and DNA were detected during HAART, in tissues from numerous anatomical locations. Additional analysis provided evidence for full-length viral RNA in tissues of animals with virus suppressed by HAART. The highest levels of vDNA and vRNA in HAART-treated macaques were in lymphoid tissues, particularly the spleen, lymph nodes, and gastrointestinal tract tissues. This study is the first comprehensive analysis of the tissue and organ distribution of a primate AIDS virus during HAART. These data demonstrate widespread persistence of residual virus in tissues during HAART.

Evaluation of the pathogenesis of decreasing CD4(+) T cell counts in human immunodeficiency virus type 1-infected patients receiving successfully suppressive antiretroviral therapy

Most human immunodeficiency virus (HIV)-infected individuals experience increases in peripheral CD4(+) T cell counts with suppressive antiretroviral therapy (ART) that achieves plasma HIV RNA levels that are less than the limit of detection. However, some individuals experience decreasing CD4(+) T cell counts despite suppression of plasma viremia. We evaluated 4 patients with a history of CD4(+) T cell decline despite successfully suppressive ART, from a median of 719 cells/mm(3) (range, 360-1141 cells/mm(3)) to 227 cells/mm(3) (range, 174-311 cells/mm(3)) over a period of 18-24 months; 3 of the patients were receiving tenofovir and didanosine, which may have contributed to this decrease. There was no evidence of HIV replication, nor of antiretroviral drug resistance in the blood or lymphoid tissue, or increased proliferation or decreased thymic production of naive CD4(+) T cells. All 4 patients had significant fibrosis of the T cell zone of lymphoid tissue, which appeared to be an important factor in the failure to reconstitute T cells.

Emerging pharmacology: inhibitors of human immunodeficiency virus integration

The first integrase inhibitor licensed to treat HIV-1 infection was approved in late 2007, more than a decade after the introduction of the first inhibitors of the HIV-1 reverse transcriptase and protease. The unique biochemical and molecular mechanism of action of this novel class of antiretroviral drugs is the fundamental basis for their activity in treating multidrug-resistant HIV-1 infection and is important for understanding both the cellular and in vivo pharmacology and metabolism of these agents. In addition, available pharmacokinetic and drug interaction data for raltegravir and elvitegravir, the two integrase inhibitors that are the most advanced in clinical development to date, are reviewed.