Understanding the mechanisms driving the spread of subtype C HIV-1

Impact of subtype C-specific amino acid variants on HIV-1 Tat-TAR interaction: insights from molecular modelling and dynamics

BACKGROUND

HIV-1 produces Tat, a crucial protein for transcription, viral replication, and CNS neurotoxicity. Tat interacts with TAR, enhancing HIV reverse transcription. Subtype C Tat variants (C31S, R57S, Q63E) are associated with reduced transactivation and neurovirulence compared to subtype B. However, their precise impact on Tat-TAR binding is unclear. This study investigates how these substitutions affect Tat-TAR interaction.

METHODS

We utilized molecular modelling techniques, including MODELLER, to produce precise three-dimensional structures of HIV-1 Tat protein variants. We utilized Tat subtype B as the reference or wild type, and generated Tat variants to mirror those amino acid variants found in Tat subtype C. Subtype C-specific amino acid substitutions were selected based on their role in the neuropathogenesis of HIV-1. Subsequently, we conducted molecular docking of each Tat protein variant to TAR using HDOCK, followed by molecular dynamic simulations.

RESULTS

Molecular docking results indicated that Tat subtype B (TatWt) showed the highest affinity for the TAR element (-262.07), followed by TatC31S (-261.61), TatQ63E (-256.43), TatC31S/R57S/Q63E (-238.92), and TatR57S (-222.24). However, binding free energy analysis showed higher affinities for single variants TatQ63E (-349.2 ± 10.4 kcal/mol) and TatR57S (-290.0 ± 9.6 kcal/mol) compared to TatWt (-247.9 ± 27.7 kcal/mol), while TatC31S and TatC31S/R57SQ/63E showed lower values. Interactions over the protein trajectory were also higher for TatQ63E and TatR57S compared to TatWt, TatC31S, and TatC31S/R57SQ/63E, suggesting that modifying amino acids within the Arginine/Glutamine-rich region notably affects TAR interaction. Single amino acid mutations TatR57S and TatQ63E had a significant impact, while TatC31S had minimal effect. Introducing single amino acid variants from TatWt to a more representative Tat subtype C (TatC31S/R57SQ/63E) resulted in lower predicted binding affinity, consistent with previous findings.

CONCLUSIONS

These identified amino acid positions likely contribute significantly to Tat-TAR interaction and the differential pathogenesis and neuropathogenesis observed between subtype B and subtype C. Additional experimental investigations should prioritize exploring the influence of these amino acid signatures on TAR binding to gain a comprehensive understanding of their impact on viral transactivation, potentially identifying them as therapeutic targets.

Alterations in the Gut Microbiome Composition of People Living with HIV in the Asia-Pacific Region: A Systematic Review

Human immunodeficiency virus (HIV) infection continues to present a global health issue. Recent studies have explored the potential role of the gut microbiome in HIV infection for novel therapeutic approaches. We investigated the gut microbiome composition of people living with HIV (PLHIV) in the Asia-Pacific region. This review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. An electronic search was conducted in the PubMed/MEDLINE, Scopus, and ScienceDirect databases using keywords such as "HIV", "PLHIV", "AIDS", "gut microbiome", "gut dysbiosis", and "metagenomics". Only peer-reviewed and full-text studies published in English were included. A total of 15 studies from the Asia-Pacific region were included for analysis. Compared to healthy controls, PLHIV showed an increased abundance of Proteobacteria and its genera, which may be considered pathobionts, and decreased abundances of Bacteroidetes and several genera under Firmicutes with known short-chain fatty acid and immunoregulatory activities. Predominant taxa such as Ruminococcaceae and Prevotellaceae were also associated with clinical factors such as CD4 count, the CD4/CD8 ratio, and inflammatory cytokines. This review highlights gut microbiome changes among PLHIV in the Asia-Pacific region, indicating potential bacterial signatures for prognostication. The partial restoration of the microbiome toward beneficial taxa may ensure the long-term success of treatment, promoting immune recovery while maintaining viral load suppression.

A systematic review and meta-analysis of HIV transmission risk behaviors, genetic variations, and antiretroviral (ARV) resistance in LGBT populations

Background

Currently, human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS) has become one of the major health problems worldwide, including Indonesia. East Java is one of the provinces in Indonesia with the highest prevalence of HIV infection. One of the causes of HIV infection transmission is lesbian, gay, bisexual, and transgender (LGBT) practice. Furthermore, the treatment using antiretroviral (ARV) drugs in HIV-1 patients can fail due to the presence of HIV drug resistance.

Objective

The aim of this study is to identify the behavior at risk of HIV transmission among LGBT, patterns of genetic variation and antiretroviral (ARV) resistance.

Methods

A systematic review and meta-analysis based on the PRISMA guidelines was conducted. We searched three databases including PubMed, ScienceDirect, and Google scholar for studies investigating the non-heterosexual behavior as risk factor of HIV infection and antiretroviral resistance. Only studies published in English are considered. The adjusted estimates of the risk were carried out using best-adjusted OR with 95% confidence interval (CI) and significant p value < 0.05.

Results

In the quantitative analysis of HIV infection risk factors, a total of 13 studies were included, which investigated non-heterosexual behavior as a potential factor. The studies involved a total of 37,129 participants, comprising 10,449 individuals in the non-heterosexual behavior group (LGBTQ+) and 26,680 individuals in the heterosexual group. The majority of the participants in this study were from the USA, Japan, China, and Brazil, and the main HIV subgenotypes were B and CRF. Additionally, the antiretroviral resistance of HIV patients was examined, involving a total of 3062 individuals, with 1296 individuals in the non-heterosexual behavior group and 1766 individuals in the heterosexual group. Our calculation showed that non-heterosexual behavior was significant as risk factor of HIV infection (OR = 2.17, 95% CI = 1.94-2.43, p < 0.001) and antiretroviral resistance (OR = 1.31, 95% CI = 1.00-1.71, p = 0.05).

Conclusion

This study concludes that non heterosexual behavior is significant risk factor of HIV infection. A quite prevalent of antiretroviral resistance were found among non heterosexual behavior. The main subgenotype of HIV are B and CRF.

Optimizing ancestral trait reconstruction of large HIV Subtype C datasets through multiple-trait subsampling

Large datasets along with sampling bias represent a challenge for phylodynamic reconstructions, particularly when the study data are obtained from various heterogeneous sources and/or through convenience sampling. In this study, we evaluate the presence of unbalanced sampled distribution by collection date, location, and risk group of human immunodeficiency virus Type 1 Subtype C using a comprehensive subsampling strategy and assess their impact on the reconstruction of the viral spatial and risk group dynamics using phylogenetic comparative methods. Our study shows that a most suitable dataset for ancestral trait reconstruction can be obtained through subsampling by all available traits, particularly using multigene datasets. We also demonstrate that sampling bias is inflated when considerable information for a given trait is unavailable or of poor quality, as we observed for the trait risk group. In conclusion, we suggest that, even if traits are not well recorded, including them deliberately optimizes the representativeness of the original dataset rather than completely excluding them. Therefore, we advise the inclusion of as many traits as possible with the aid of subsampling approaches in order to optimize the dataset for phylodynamic analysis while reducing the computational burden. This will benefit research communities investigating the evolutionary and spatio-temporal patterns of infectious diseases.

Sex differences in cognitive function among people with HIV-1 clade C infection in Northern India

Human immunodeficiency virus-1 (HIV-1) clade C is the most prevalent form of HIV-1 comprising nearly 46% of global infections and is the dominant subtype in India. Despite its predominance, the impact of HIV-1 clade C infection on cognitive function has been understudied in comparison with other subtypes, notably clade B, which is primarily found in Europe and North America. Few studies have assessed cognitive impairment in antiretroviral therapy (ART) naïve men and women with HIV-1 clade C infection. In this study conducted in Northern India, differences in neuropsychological functioning were compared between 109 participants (70 men, 39 women) with untreated HIV-1 clade C infection and 110 demographically matched healthy controls (74 men, 36 women). A comprehensive neuropsychological battery was used to examine depression, self-assessment of functioning, and cognitive performance in six domains of functioning. Group differences were assessed by HIV-1 status and sex, controlling for age and education. Results indicated that cognitive deficits were substantially greater among male participants with HIV-1 clade C compared to male controls in all domains of cognitive functioning; in contrast, women with HIV-1 clade C had only minor deficits compared to healthy female participants. In addition, a larger proportion of men with HIV-1 clade C exhibited high levels of depression than women with HIV-1 clade C. These findings suggest that untreated HIV-1 clade C infection in men can have debilitating effects on neuropsychological function and depression, and stress the importance of facilitating rapid access to treatment to reduce the impact of HIV-1 infection.

Dating reservoir formation in virologically suppressed people living with HIV-1 in Rakai, Uganda

The timing of the establishment of the HIV latent viral reservoir (LVR) is of particular interest, as there is evidence that proviruses are preferentially archived at the time of antiretroviral therapy (ART) initiation. Quantitative viral outgrowth assays (QVOAs) were performed using Peripheral Blood Mononuclear Cells (PBMC) collected from Ugandans living with HIV who were virally suppressed on ART for >1 year, had known seroconversion windows, and at least two archived ART-naïve plasma samples. QVOA outgrowth populations and pre-ART plasma samples were deep sequenced for the pol and gp41 genes. The bayroot program was used to estimate the date that each outgrowth virus was incorporated into the reservoir. Bayroot was also applied to previously published data from a South African cohort. In the Ugandan cohort (n = 11), 87.9 per cent pre-ART and 56.3 per cent viral outgrowth sequences were unique. Integration dates were estimated to be relatively evenly distributed throughout viremia in 9/11 participants. In contrast, sequences from the South African cohort (n = 9) were more commonly estimated to have entered the LVR close to ART initiation, as previously reported. Timing of LVR establishment is variable between populations and potentially viral subtypes, which could limit the effectiveness of interventions that target the LVR only at ART initiation.

A classification algorithm based on dynamic ensemble selection to predict mutational patterns of the envelope protein in HIV-infected patients

BACKGROUND

Therapeutics against the envelope (Env) proteins of human immunodeficiency virus type 1 (HIV-1) effectively reduce viral loads in patients. However, due to mutations, new therapy-resistant Env variants frequently emerge. The sites of mutations on Env that appear in each patient are considered random and unpredictable. Here we developed an algorithm to estimate for each patient the mutational state of each position based on the mutational state of adjacent positions on the three-dimensional structure of the protein.

METHODS

We developed a dynamic ensemble selection algorithm designated k-best classifiers. It identifies the best classifiers within the neighborhood of a new observation and applies them to predict the variability state of each observation. To evaluate the algorithm, we applied amino acid sequences of Envs from 300 HIV-1-infected individuals (at least six sequences per patient). For each patient, amino acid variability values at all Env positions were mapped onto the three-dimensional structure of the protein. Then, the variability state of each position was estimated by the variability at adjacent positions of the protein.

RESULTS

The proposed algorithm showed higher performance than the base learner and a panel of classification algorithms. The mutational state of positions in the high-mannose patch and CD4-binding site of Env, which are targeted by multiple therapeutics, was predicted well. Importantly, the algorithm outperformed other classification techniques for predicting the variability state at multi-position footprints of therapeutics on Env.

CONCLUSIONS

The proposed algorithm applies a dynamic classifier-scoring approach that increases its performance relative to other classification methods. Better understanding of the spatiotemporal patterns of variability across Env may lead to new treatment strategies that are tailored to the unique mutational patterns of each patient. More generally, we propose the algorithm as a new high-performance dynamic ensemble selection technique.

Per-pathogen virulence of HIV-1 subtypes A, C and D

HIV-1 subtypes differ in their clinical manifestations and the speed in which they spread. In particular, the frequency of subtype C is increasing relative to subtypes A and D. We investigate whether HIV-1 subtypes A, C and D differ in their per-pathogen virulence and to what extend this explains the difference in spread between these subtypes. We use data from the hormonal contraception and HIV-1 genital shedding and disease progression among women with primary HIV infection study. For each study participant, we determine the set-point viral load value, CD4⁺ T cell level after primary infection and CD4⁺ T cell decline. Based on both the CD4⁺ T cell count after primary infection and CD4⁺ T cell decline, we estimate the time until AIDS. We then obtain our newly introduced measure of virulence as the inverse of the estimated time until AIDS. After fitting a model to the measured virulence and set-point viral load values, we tested if this relation varies per subtype. We found that subtype C has a significantly higher per-pathogen virulence than subtype A. Based on an evolutionary model, we then hypothesize that differences in the primary length of infection period cause the observed variation in the speed of spread of the subtypes.

Generation and characterization of infectious molecular clones of transmitted/founder HIV-1 subtype C viruses

The genetic diversity of HIV impedes vaccine development. Identifying the viral properties of transmitted/founder (T/F) variants may provide a common vaccine target. To study the biological nature of T/F viruses, we constructed full-length clones from women detected during Fiebig stage I acute HIV-1 infection (AHI) from heterosexual male-to-female (MTF) transmission; and clones after one year of infection using In-Fusion-based cloning. Eighteen full-length T/F clones were generated from 9 women and six chronic infection clones were from 2 individuals. All clones but one were non-recombinant subtype C. Three of the 5 T/F clones and 3 chronic clones tested replicated efficiently in PBMCs and utilised CCR5 coreceptor for cell entry. Transmitted/founder and chronic infection clones displayed heterogenous in vitro replicative capacity and resistance to type I interferon. T/F viruses had shorter Env glycoproteins and fewer N-linked glycosylation sites in Env. Our findings suggest MTF transmission may select viruses with compact envelopes.

Gene dysregulation in acute HIV-1 infection – early transcriptomic analysis reveals the crucial biological functions affected

Introduction

Transcriptomic analyses from early human immunodeficiency virus (HIV) infection have the potential to reveal how HIV causes widespread and lasting damage to biological functions, especially in the immune system. Previous studies have been limited by difficulties in obtaining early specimens.

Methods

A hospital symptom-based screening approach was applied in a rural Mozambican setting to enrol patients with suspected acute HIV infection (Fiebig stage I-IV). Blood samples were collected from all those recruited, so that acute cases and contemporaneously recruited, uninfected controls were included. PBMC were isolated and sequenced using RNA-seq. Sample cellular composition was estimated from gene expression data. Differential gene expression analysis was completed, and correlations were determined between viral load and differential gene expression. Biological implications were examined using Cytoscape, gene set enrichment analysis, and enrichment mapping.

Results

Twenty-nine HIV infected subjects one month from presentation and 46 uninfected controls were included in this study. Subjects with acute HIV infection demonstrated profound gene dysregulation, with 6131 (almost 13% of the genome mapped in this study) significantly differentially expressed. Viral load was correlated with 1.6% of dysregulated genes, in particular, highly upregulated genes involved in key cell cycle functions, were correlated with viremia. The most profoundly upregulated biological functions related to cell cycle regulation, in particular, CDCA7 may drive aberrant cell division, promoted by overexpressed E2F family proteins. Also upregulated were DNA repair and replication, microtubule and spindle organization, and immune activation and response. The interferome of acute HIV was characterized by broad activation of interferon-stimulated genes with antiviral functions, most notably IFI27 and OTOF. BCL2 downregulation alongside upregulation of several apoptotic trigger genes and downstream effectors may contribute to cycle arrest and apoptosis. Transmembrane protein 155 (TMEM155) was consistently highly overexpressed during acute infection, with roles hitherto unknown.

Discussion

Our study contributes to a better understanding of the mechanisms of early HIV-induced immune damage. These findings have the potential to lead to new earlier interventions that improve outcomes.

HIV-1 Tat amino acid residues that influence Tat-TAR binding affinity: a scoping review

HIV-1 remains a global health concern and to date, nearly 38 million people are living with HIV. The complexity of HIV-1 pathogenesis and its subsequent prevalence is influenced by several factors including the HIV-1 subtype. HIV-1 subtype variation extends to sequence variation in the amino acids of the HIV-1 viral proteins. Of particular interest is the transactivation of transcription (Tat) protein due to its key function in viral transcription. The Tat protein predominantly functions by binding to the transactivation response (TAR) RNA element to activate HIV-1 transcriptional elongation. Subtype-specific Tat protein sequence variation influences Tat-TAR binding affinity. Despite several studies investigating Tat-TAR binding, it is not clear which regions of the Tat protein and/or individual Tat amino acid residues may contribute to TAR binding affinity. We, therefore, conducted a scoping review on studies investigating Tat-TAR binding. We aimed to synthesize the published data to determine (1) the regions of the Tat protein that may be involved in TAR binding, (2) key Tat amino acids involved in TAR binding and (3) if Tat subtype-specific variation influences TAR binding. A total of thirteen studies met our inclusion criteria and the key findings were that (1) both N-terminal and C-terminal amino acids outside the basic domain (47-59) may be important in increasing Tat-TAR binding affinity, (2) substitution of the amino acids Lysine and Arginine (47-59) resulted in a reduction in binding affinity to TAR, and (3) none of the included studies have investigated Tat subtype-specific substitutions and therefore no commentary could be made regarding which subtype may have a higher Tat-TAR binding affinity. Future studies investigating Tat-TAR binding should therefore use full-length Tat proteins and compare subtype-specific variations. Studies of such a nature may help explain why we see differential pathogenesis and prevalence when comparing HIV-1 subtypes.

HIV-1 Transmission Cluster in Injection Drug Users in Nairobi City, Kenya

Background

While there is a striking increase in the prevalence of HIV in injection drug users, information on envelope-gene subtypes and transmission clusters in injection drug users is scarce.

Method

In a cross-sectional study, 247 injection drug users were recruited via out-rich method. Deoxyribonucleic acid was extracted from dry blood spot samples, amplified by Polymerase Chain Reaction and sequenced. Subtyping was performed using COntext-based Modeling for Expeditious Typing (COMET) and Recombinant Identification Program (RIP) tools. Phylogenetic diversity and Transmission clusters were identified using MEGA version 6.0 and TreeLink, respectively.

Results

Overall, 42 (17.0%) injection drug users were sero-positive for HIV-1. Of the 37 samples successfully sequenced, 29 (78.4%) sequences were identified as A1, 6 (16.2%) as AG while 1 (2.7%) as A1/G/AE and A1/C recombinants. The HIV subtypes formed clusters with little genetic diversity.

Conclusion

The high HIV prevalence was associated with transmission clusters and diversity in subtypes indicating ongoing local transmission. Therefore, there is need for comprehensive HIV care tailored to this population.

HIV and Drug-Resistant Subtypes

Acquired Immunodeficiency Syndrome (AIDS) is a human viral infectious disease caused by the positive-sense single-stranded (ss) RNA Human Immunodeficiency Virus (HIV) (Retroviridae family, Ortervirales order). HIV-1 can be distinguished into various worldwide spread groups and subtypes. HIV-2 also causes human immunodeficiency, which develops slowly and tends to be less aggressive. HIV-2 only partially homologates to HIV-1 despite the similar derivation. Antiretroviral therapy (ART) is the treatment approved to control HIV infection, based on multiple antiretroviral drugs that belong to different classes: (i) NNRTIs, (ii) NRTIs, (iii) PIs, (iv) INSTIs, and (v) entry inhibitors. These drugs, acting on different stages of the HIV life cycle, decrease the patient's total burden of HIV, maintain the function of the immune system, and prevent opportunistic infections. The appearance of several strains resistant to these drugs, however, represents a problem today that needs to be addressed as best as we can. New outbreaks of strains show a widespread geographic distribution and a highly variable mortality rate, even affecting treated patients significantly. Therefore, novel treatment approaches should be explored. The present review discusses updated information on HIV-1- and HIV-2-resistant strains, including details on different mutations responsible for drug resistance.

Awareness and Willingness to use Condoms and Preexposure Prophylaxis among Gay, Bisexual, and Other Cisgendered Men who Have sex with men in Slum Communities in Ghana. BSGH-004

Introduction: Research has begun to examine human immunodeficiency virus (HIV) prevention strategies within the Ghanaian context. Still, little is known about specific populations such as gay, bisexual, and other cisgender men who have sex with men (GBMSM) living in slum communities. We studied HIV prevention strategies such as condoms and preexposure prophylaxis (PrEP) in slum communities and the awareness and willingness to use these choices among GBMSM. This qualitative study examines HIV prevention strategies, specifically examining PrEP and condom use behaviors among GBMSM in Ghana. Methods: We conducted in-depth face-to-face interviews among 12 GBMSM from slums in Accra and Kumasi cities in Ghana. Data were analyzed through a summative content analysis with multiple reviewers to develop codes. Data were collected from participants in January 2022. Results: We found the fear and perceived risk of infection were motivators for consistent condom use, especially during anal sex. GBMSM living with HIV receiving antiretroviral therapy were more inclined to use condoms. We found motivations for using PrEP were influenced by the type of sexual activity and a history of negative HIV status. Also, the barriers to PrEP for GBMSM included limited access to healthcare facilities and the distance to these facilities. Conclusions: To improve condom and PrEP access and uptake, we recommend addressing structural barriers by increasing the number of health facilities and implementing targeted interventions to address the lack of information on HIV awareness and prevention. Involving peer educators may also effectively promote HIV prevention strategies, especially in communities with limited access to healthcare such as slums. Overcoming these access constraints could significantly enhance awareness and prevention of HIV, leading to improved health outcomes for GBMSM living in slum communities.

Systematic post-mortem analysis of brain tissue from an HIV-1 subtype C viremic decedent revealed a paucity of infection and pathology

Whether the human brain is a robust reservoir for HIV-1 subtype C has yet to be established. We aimed to determine whether HIV-1 subtype C infection can be detected in the brain tissue of a viremic individual at post-mortem and whether the viral burden was differential between different brain regions. This study reports a 38-year-old Zambian female decedent with severe wasting who was on Atripla for antiretroviral therapy. The cause of death was determined to be HIV/AIDS end-stage disease. The QuantStudio 3 Real-Time PCR System analyzed formalin-fixed paraffin-embedded tissue DNA from a systematic sampling of the entire left-brain hemisphere. Plasma and cerebral spinal fluid HIV-1 RNA loads were 576,123 and 14,962 copies/mL, respectively. The lymph node DNA viral load was 2316 copies per 106 cells. Two hundred and six (96.3%) tissue blocks had amplifiable DNA. HIV-1 viral DNA was detected in 35.9% of the blocks, the highest in the basal ganglia (66.7%) and the frontal lobe (46%). Overall, HIV detection was random, with low viral copies detected by quantitative polymerase chain reaction (qPCR); the lowest was observed in the occipital (median, IQR, range) 0.0 [0.0-0.0], 0.0-31.3, and the highest in the basal ganglia (mean ± SD, range, 125.1149.5, 0.0-350.0). Significant differences in HIV-1 DNA distribution were observed between the occipital versus parietal (p = 0.049), occipital versus frontal (p = 0.019), occipital versus basal ganglia (p = 0.005), cerebellum versus frontal (p = 0.021), cerebellum versus basal ganglia (p = 0.007), and temporal versus frontal (p = 0.034).

Antiretroviral (ARV) Drug Resistance and HIV-1 Subtypes among Injecting Drug Users in the Coastal Region of Kenya

HIV-1 genetic diversity results into the development of widespread drug-resistant mutations (DRMs) for the first-line retroviral therapy. Nevertheless, few studies have investigated the relationship between DRMs and HIV-1 subtypes among HIV-positive injecting drug users (IDUs). This study therefore determined the association between HIV-1 genotypes and DRMs among the 200 IDUs. Stanford HIV Drug Resistance Database was used to interpret DRMs. The five HIV-1 genotypes circulating among the IDUs were A₁ (25 (53.2%)), A₂ (2 (4.3%)), B (2 (4.3%)), C (9 (19.1%)), and D (9 (19.1%)). The proportions of DRMs were A₁ (12 (52.2%)), A₂ (1 (4.3%)), B (0 (0.0%)), C (5 (21.7%)), and D (5 (21.7%)). Due to the large proportion of drug resistance across all HIV-1 subtypes, surveillance and behavioral studies need to be explored as IDUs may be spreading the drug resistance to the general population. In addition, further characterization of DRMs including all the relevant clinical parameters among the larger population of IDUs is critical for effective drug resistance surveillance.

HIV reservoir quantification using cross-subtype multiplex ddPCR

A major barrier to conducting HIV cure research in populations with the highest HIV burden is the lack of an accurate assay to quantify the replication-competent reservoir across the dominant global HIV-1 subtypes. Here, we modify a subtype B HIV-1 assay that quantifies both intact and defective proviral DNA, adapting it to accommodate cross-subtype HIV-1 sequence diversity. We show that the cross-subtype assay works on subtypes A, B, C, D, and CRF01_AE and can detect a single copy of intact provirus. In longitudinal blood samples from Kenyan infants infected with subtypes A and D, patterns of intact and total HIV DNA follow the decay of plasma viral load over time during antiretroviral therapy, with intact HIV DNA comprising 7% (range 1%-33%) of the total HIV DNA during HIV RNA suppression. This high-throughput cross-subtype reservoir assay will be useful in HIV cure research in Africa and Asia, where HIV prevalence is highest.

A landscape planning agenda for global health security: Learning from the history of HIV/AIDS and pandemic influenza

This paper considers the role of landscape planning and design in the context of a growing need for research and policy recommendations associated with Emerging Infectious Diseases (EIDs), of which COVID-19 is the most recent. Beginning with a definition of EIDs and their origins within the context of landscape planning, the paper then argues that planning and design scholars and practitioners should begin by seeing the importance of a "global urban ecosystem" (GUE) comprised of rapidly transforming metropolitan and regional "patches" connected through "corridors" of relatively unregulated global transportation and mobility networks. It then revisits the history of the two prior global pandemics of HIV/AIDS and pandemic influenza to establish the importance of a landscape planning perspective at the intersection of wildlife, livestock, and globally connected human communities. The essay concludes by arguing that this GUE concept can facilitate creative planning and design by adapting concepts established in other patch and corridor networks like urban transit systems to the ongoing risk of future pandemic EIDs.

Evolutionary dynamics of HIV-1 subtype C in Brazil

The extensive genetic diversity of HIV-1 is a major challenge for the prevention and treatment of HIV-1 infections. Subtype C accounts for most of the HIV-1 infections in the world but has been mainly localized in Southern Africa, Ethiopia and India. For elusive reasons, South Brazil harbors the largest HIV-1 subtype C epidemic in the American continent that is elsewhere dominated by subtype B. To investigate this topic, we collected clinical data and viral sequences from 2611 treatment-naïve patients diagnosed with HIV-1 in Brazil. Molecular epidemiology analysis supported 35 well-delimited transmission clusters of subtype C highlighting transmission within South Brazil but also from the South to all other Brazilian regions and internationally. Individuals infected with subtype C had lower probability to be deficient in CD4⁺ T cells when compared to subtype B. The HIV-1 epidemics in the South was characterized by high female-to-male infection ratios and women-to-child transmission. Our results suggest that HIV-1 subtype C probably takes advantage of longer asymptomatic periods to maximize transmission and is unlikely to outcompete subtype B in settings where the infection of women is relatively less relevant. This study contributes to elucidate factors possibly underlying the geographical distribution and expansion patterns of the most spread HIV-1 subtypes.

Breadth of CD8 T-cell mediated inhibition of replication of diverse HIV-1 transmitted-founder isolates correlates with the breadth of recognition within a comprehensive HIV-1 Gag, Nef, Env and Pol potential T-cell epitope (PTE) peptide set

Full characterisation of functional HIV-1-specific T-cell responses, including identification of recognised epitopes linked with functional antiviral responses, would aid development of effective vaccines but is hampered by HIV-1 sequence diversity. Typical approaches to identify T-cell epitopes utilising extensive peptide sets require subjects' cell numbers that exceed feasible sample volumes. To address this, CD8 T-cells were polyclonally expanded from PBMC from 13 anti-retroviral naïve subjects living with HIV using CD3/CD4 bi-specific antibody. Assessment of recognition of individual peptides within a set of 1408 HIV-1 Gag, Nef, Pol and Env potential T-cell epitope peptides was achieved by sequential IFNγ ELISpot assays using peptides pooled in 3-D matrices followed by confirmation with single peptides. A Renilla reniformis luciferase viral inhibition assay assessed CD8 T-cell-mediated inhibition of replication of a cross-clade panel of 10 HIV-1 isolates, including 9 transmitted-founder isolates. Polyclonal expansion from one frozen PBMC vial provided sufficient CD8 T-cells for both ELISpot steps in 12 of 13 subjects. A median of 33 peptides in 16 epitope regions were recognised including peptides located in previously characterised HIV-1 epitope-rich regions. There was no significant difference between ELISpot magnitudes for in vitro expanded CD8 T-cells and CD8 T-cells directly isolated from PBMCs. CD8 T-cells from all subjects inhibited a median of 7 HIV-1 isolates (range 4 to 10). The breadth of CD8 T-cell mediated HIV-1 inhibition was significantly positively correlated with CD8 T-cell breadth of peptide recognition. Polyclonal CD8 T-cell expansion allowed identification of HIV-1 isolates inhibited and peptides recognised within a large peptide set spanning the major HIV-1 proteins. This approach overcomes limitations associated with obtaining sufficient cell numbers to fully characterise HIV-1-specific CD8 T-cell responses by different functional readouts within the context of extreme HIV-1 diversity. Such an approach will have useful applications in clinical development for HIV-1 and other diseases.

CRISPR-Cas9 Mediated Exonic Disruption for HIV-1 Elimination

BACKGROUND

A barrier to HIV-1 cure rests in the persistence of proviral DNA in infected CD4+ leukocytes. The high HIV-1 mutation rate leads to viral diversity, immune evasion, and consequent antiretroviral drug resistance. While CRISPR-spCas9 can eliminate latent proviral DNA, its efficacy is limited by HIV strain diversity and precision target cell delivery.

METHODS

A library of guide RNAs (gRNAs) designed to disrupt five HIV-1 exons (tat1-2/rev1-2/gp41) was constructed. The gRNAs were derived from a conseensus sequence of the transcriptional regulator tat from 4004 HIV-1 strains. Efficacy was affirmed by gRNA cell entry through transfection, electroporation, or by lentivirus or lipid nanoparticle (LNP) delivery. Treated cells were evaluated for viral excision by monitoring HIV-1 DNA, RNA, protein, and progeny virus levels.

FINDINGS

Virus was reduced in all transmitted founder strains by 82 and 94% after CRISPR TatDE transfection or lentivirus treatments, respectively. No recorded off-target cleavages were detected. Electroporation of TatDE ribonucleoprotein and delivery of LNP TatDE gRNA and spCas9 mRNA to latently infected cells resulted in up to 100% viral excision. Protection against HIV-1-challenge or induction of virus during latent infection, in primary or transformed CD4+ T cells or monocytes was achieved. We propose that multi-exon gRNA TatDE disruption delivered by LNPs enables translation for animal and human testing.

INTERPRETATION

These results provide "proof of concept' for CRISPR gRNA treatments for HIV-1 elimination. The absence of full-length viral DNA by LNP delivery paired with undetectable off-target affirms the importance of payload delivery for effective viral gene editing.

FUNDING

The work was supported by the University of Nebraska Foundation, including donations from the Carol Swarts, M.D. Emerging Neuroscience Research Laboratory, the Margaret R. Larson Professorship, and individual donor support from the Frances and Louie Blumkin Foundation and from Harriet Singer. The research received support from National Institutes of Health grants T32 NS105594, 5R01MH121402, 1R01Al158160, R01 DA054535, PO1 DA028555, R01 NS126089, R01 NS36126, PO1 MH64570, P30 MH062261, and 2R01 NS034239.

Residues T48 and A49 in HIV-1 NL4-3 Nef are responsible for the counteraction of autophagy initiation, which prevents the ubiquitin-dependent degradation of Gag through autophagosomes

BACKGROUND

Autophagy plays an important role as a cellular defense mechanism against intracellular pathogens, like viruses. Specifically, autophagy orchestrates the recruitment of specialized cargo, including viral components needed for replication, for lysosomal degradation. In addition to this primary role, the cleavage of viral structures facilitates their association with pattern recognition receptors and MHC-I/II complexes, which assists in the modulation of innate and adaptive immune responses against these pathogens. Importantly, whereas autophagy restricts the replicative capacity of human immunodeficiency virus type 1 (HIV-1), this virus has evolved the gene nef to circumvent this process through the inhibition of early and late stages of the autophagy cascade. Despite recent advances, many details of the mutual antagonism between HIV-1 and autophagy still remain unknown. Here, we uncover the genetic determinants that drive the autophagy-mediated restriction of HIV-1 as well as the counteraction imposed by Nef. Additionally, we also examine the implications of autophagy antagonism in HIV-1 infectivity.

RESULTS

We found that sustained activation of autophagy potently inhibits HIV-1 replication through the degradation of HIV-1 Gag, and that this effect is more prominent for nef-deficient viruses. Gag re-localizes to autophagosomes where it interacts with the autophagosome markers LC3 and SQSTM1. Importantly, autophagy-mediated recognition and recruitment of Gag requires the myristoylation and ubiquitination of this virus protein, two post-translational modifications that are essential for Gag's central role in virion assembly and budding. We also identified residues T48 and A49 in HIV-1 NL4-3 Nef as responsible for impairing the early stages of autophagy. Finally, a survey of pandemic HIV-1 transmitted/founder viruses revealed that these isolates are highly resistant to autophagy restriction.

CONCLUSIONS

This study provides evidence that autophagy antagonism is important for virus replication and suggests that the ability of Nef to counteract autophagy may have played an important role in mucosal transmission. Hence, disabling Nef in combination with the pharmacological manipulation of autophagy represents a promising strategy to prevent HIV spread.

Structurally related but genetically unrelated antibody lineages converge on an immunodominant HIV-1 Env neutralizing determinant following trimer immunization

Understanding the molecular mechanisms by which antibodies target and neutralize the HIV-1 envelope glycoprotein (Env) is critical in guiding immunogen design and vaccine development aimed at eliciting cross-reactive neutralizing antibodies (NAbs). Here, we analyzed monoclonal antibodies (mAbs) isolated from non-human primates (NHPs) immunized with variants of a native flexibly linked (NFL) HIV-1 Env stabilized trimer derived from the tier 2 clade C 16055 strain. The antibodies displayed neutralizing activity against the autologous virus with potencies ranging from 0.005 to 3.68 μg/ml (IC50). Structural characterization using negative-stain EM and X-ray crystallography identified the variable region 2 (V2) of the 16055 NFL trimer to be the common epitope for these antibodies. The crystal structures revealed that the V2 segment adopts a β-hairpin motif identical to that observed in the 16055 NFL crystal structure. These results depict how vaccine-induced antibodies derived from different clonal lineages penetrate through the glycan shield to recognize a hypervariable region within V2 (residues 184-186) that is unique to the 16055 strain. They also provide potential explanations for the potent autologous neutralization of these antibodies, confirming the immunodominance of this site and revealing that multiple angles of approach are permissible for affinity/avidity that results in potent neutralizing capacity. The structural analysis reveals that the most negatively charged paratope correlated with the potency of the mAbs. The atomic level information is of interest to both define the means of autologous neutralization elicited by different tier 2-based immunogens and facilitate trimer redesign to better target more conserved regions of V2 to potentially elicit cross-neutralizing HIV-1 antibodies.

An additional NF-κB site allows HIV-1 subtype C to evade restriction by nuclear PYHIN proteins

Subtype C is the most prevalent clade of human immunodeficiency virus type 1 (HIV-1) worldwide. The reasons for this are poorly understood. Here, we demonstrate that a characteristic additional third nuclear factor κB (NF-κB) binding site in the long terminal repeat (LTR) promoter allows subtype C HIV-1 strains to evade restriction by nuclear PYHIN proteins, which sequester the transcription factor Sp1. Further, other LTR alterations are responsible for rare PYHIN resistance of subtype B viruses. Resistance-conferring mutations generally reduce the dependency of HIV-1 on Sp1 for virus production and render LTR transcription highly responsive to stimulation by NF-κB/p65. A third NF-κB binding site increases infectious virus yield in primary CD4+ T cells in an γ-interferon-inducible protein 16 (IFI16)-dependent manner. Comprehensive sequence analyses suggest that the frequency of circulating PYHIN-resistant HIV-1 strains is increasing. Our finding that an additional NF-κB binding site in the LTR confers resistance to nuclear PYHIN proteins helps to explain the dominance of clade C HIV-1 strains.

Epidemiological profile and molecular genetic characterization of HIV-1 among female sex workers and elderly male clients in Guangxi, China

The HIV/AIDS prevalence in female sex workers (FSWs) and elderly male clients is increasing in Guangxi, China, but the transmission relationship between them remains unclear. This study aims to illuminate the transmission network between FSWs and elderly male clients using molecular epidemiological analyses. Phylogenetic analysis indicated that CRF01_AE was the dominant strain, followed by CRF07_BC and CRF08_BC in both groups. Multivariate logistic regression analysis indicated that viral loads of 50 to 1000 copies/mL, immunological treatment failure and CRF07_BC were risk factors for entering the transmission network. Transmission network analysis showed that CRF07_BC tended to form large clusters, whereas CRF01_AE tended to form multiple but small clusters. Two groups of 11 FSWs and 169 clients were intricately intertwined. Spatial analysis demonstrated the formation of hotspots and clusters of transmission sharing regional differences. In conclusion, our study provides direct genetic evidence of transmission linkages between FSWs and elderly male clients. Although the CRF01_AE subtype was still the predominant subtype in the region, the higher degree and larger clusters found in CRF07_BC illustrate a rapid and intensive uptrend, which is expected to increase its prevalence in the region in the future.

Short Communication: Acquisition of Additional Nuclear Factor Kappa B Binding Sites in Long Terminal Repeat of Genetically Evolving HIV-1 Subtype C Viral Species in Host with Comorbidities

HIV-1 causes millions of deaths around the world. Higher disease progression and mortality are seen in HIV positive individuals with comorbidities. Two of the most pertinent conditions are coinfection with Mycobacterium tuberculosis and Intravenous Drug abuse. The mechanisms involved, however, still remain unresolved. To elucidate the mechanisms involved, we evaluated the genetic alterations in terms of additional nuclear factor kappa B (NF-κB) sites in the long terminal repeat (LTR) of HIV-1 subtype-C isolates from infected human individuals from North India, supposedly acquired by the emerging viral quasi-species in the infected host in presence of these two comorbid conditions. Interestingly the results indicate higher number of NF-κB sites in the viral isolates from HIV-tuberculosis coinfected (n = 26, 16 isolates with 3 sites and 10 isolates with 2 sites) and intravenous drug users (n = 20, 13 isolates with 3 sites and 7 isolates with 2 sites) compared to the mono-infected hosts (n = 30, 10 isolates with 3 sites, 18 isolates with 2 sites, 2 isolates with 1 site). The biological relevance of these alterations in the NF-κB sites within the HIV-1 LTR with respect to viral replicative capacity and HIV disease progression needs to be studied further.

Design and evaluation of novel piperidine HIV-1 protease inhibitors with potency against DRV-resistant variants

A novel class of HIV-1 protease inhibitors with flexible piperidine as the P2 ligand was designed with the aim of improving extensive interactions with the active subsites. Many inhibitors exhibited good to excellent inhibitory effect on enzymatic activity and viral infectivity. In particular, inhibitor 3a with (R)-piperidine-3-carboxamide as the P2 ligand and 4-methoxybenzenesulfonamide as the P2' ligand showed an enzyme K_i value of 29 pM and antiviral IC₅₀ value of 0.13 nM, more than six-fold enhancement of activity compared to DRV. Furthermore, there was no significant change in potency against DRV-resistant mutations and HIV-1_NL4-3 variant for 3a. Besides, inhibitor 3a exhibited potent antiviral activity against subtype C variants with low nanomole EC₅₀ values. In addition, the molecular modeling revealed important hydrogen bonds and other favorable van der Waals interactions with the backbone atoms of the protease and provided insight for designing and optimizing more potent HIV-1 protease inhibitors.

Immune Responses and Viral Persistence in Simian/Human Immunodeficiency Virus SHIV.C.CH848-Infected Rhesus Macaques

SHIVs have been extensively used in a nonhuman primate (NHP) model for HIV research. In this study, we investigated viral reservoirs in tissues and immune responses in an NHP model inoculated with newly generated transmitted/founder HIV-1 clade C-based SHIV.C.CH848.

Chimeric simian/human immunodeficiency viruses (SHIVs) are widely used in nonhuman primate models to recapitulate human immunodeficiency virus (HIV) infection in humans, yet most SHIVs fail to establish persistent viral infection. We investigated immunological and virological events in rhesus macaques infected with the newly developed SHIV.C.CH848 (SHIVC) and treated with combined antiretroviral therapy (cART). Similar to HIV/simian immunodeficiency virus (SIV) infection, SHIV.C.CH848 infection established viral reservoirs in CD4⁺ T cells and myeloid cells, accompanied by productive infection and depletion of CD4⁺ T cells in systemic and lymphoid tissues throughout SHIV infection. Despite 6 months of cART-suppressed viral replication, integrated proviral DNA levels remained stable, especially in CD4⁺ T cells, and the viral rebound was also observed after ART interruption. Autologous neutralizing antibodies to the parental HIV-1 strain CH848 were detected, with limited viral evolution at 5 months postinfection. In comparison, heterogenous neutralizing antibodies in SHIV.C.CH848-infected macaques were not detected except for 1 (1 of 10) animal at 2 years postinfection. These findings suggest that SHIV.C.CH848, a novel class of transmitted/founder SHIVs, can establish sustained viremia and viral reservoirs in rhesus macaques with clinical immunodeficiency consequences, providing a valuable SHIV model for HIV research.

IMPORTANCE SHIVs have been extensively used in a nonhuman primate (NHP) model for HIV research. In this study, we investigated viral reservoirs in tissues and immune responses in an NHP model inoculated with newly generated transmitted/founder HIV-1 clade C-based SHIV.C.CH848. The data show that transmitted founder (T/F) SHIVC infection of macaques more closely recapitulates the virological and clinical features of HIV infection, including persistent viremia and viral rebound once antiretroviral therapy is discontinued. These results suggest this CCR5-tropic, SHIVC strain is valuable for testing responses to HIV vaccines and therapeutics.

Gut Microbiome Profiles and Associated Metabolic Pathways in HIV-Infected Treatment-Naïve Patients

The normal composition of the intestinal microbiota is a key factor for maintaining healthy homeostasis, and accordingly, dysbiosis is well known to be present in HIV-1 patients. This article investigates the gut microbiota profile of antiretroviral therapy-naive HIV-1 patients and healthy donors living in Latin America in a cohort of 13 HIV positive patients (six elite controllers, EC, and seven non-controllers, NC) and nine healthy donors (HD). Microbiota compositions in stool samples were determined by sequencing the V3-V4 region of the bacterial 16S rRNA, and functional prediction was inferred using PICRUSt. Several taxa were enriched in EC compared to NC or HD groups, including Acidaminococcus, Clostridium methylpentosum, Barnesiella, Eubacterium coprostanoligenes, and Lachnospiraceae UCG-004. In addition, our data indicate that the route of infection is an important factor associated with changes in gut microbiome composition, and we extend these results by identifying several metabolic pathways associated with each route of infection. Importantly, we observed several bacterial taxa that might be associated with different viral subtypes, such as Succinivibrio, which were more abundant in patients infected by HIV subtype B, and Streptococcus enrichment in patients infected by subtype C. In conclusion, our data brings a significant contribution to the understanding of dysbiosis-associated changes in HIV infection and describes, for the first time, differences in microbiota composition according to HIV subtypes. These results warrant further confirmation in a larger cohort of patients.

Clusters of sub-Saharan African countries based on sociobehavioural characteristics and associated HIV incidence

Introduction

HIV incidence varies widely between sub-Saharan African (SSA) countries. This variation coincides with a substantial sociobehavioural heterogeneity, which complicates the design of effective interventions. In this study, we investigated how sociobehavioural heterogeneity in sub-Saharan Africa could account for the variance of HIV incidence between countries.

Methods

We analysed aggregated data, at the national-level, from the most recent Demographic and Health Surveys of 29 SSA countries (2010–2017), which included 594,644 persons (183,310 men and 411,334 women). We preselected 48 demographic, socio-economic, behavioural and HIV-related attributes to describe each country. We used Principal Component Analysis to visualize sociobehavioural similarity between countries, and to identify the variables that accounted for most sociobehavioural variance in SSA. We used hierarchical clustering to identify groups of countries with similar sociobehavioural profiles, and we compared the distribution of HIV incidence (estimates from UNAIDS) and sociobehavioural variables within each cluster.

Results

The most important characteristics, which explained 69% of sociobehavioural variance across SSA among the variables we assessed were: religion; male circumcision; number of sexual partners; literacy; uptake of HIV testing; women’s empowerment; accepting attitude toward people living with HIV/AIDS; rurality; ART coverage; and, knowledge about AIDS. Our model revealed three groups of countries, each with characteristic sociobehavioural profiles. HIV incidence was mostly similar within each cluster and different between clusters (median (IQR); 0.5/1000 (0.6/1000), 1.8/1000 (1.3/1000) and 5.0/1000 (4.2/1000)).

Conclusions

Our findings suggest that the combination of sociobehavioural factors play a key role in determining the course of the HIV epidemic, and that similar techniques can help to predict the effects of behavioural change on the HIV epidemic and to design targeted interventions to impede HIV transmission in SSA.

Pharmacokinetics and predicted neutralisation coverage of VRC01 in HIV-uninfected participants of the Antibody Mediated Prevention (AMP) trials

The phase 2b AMP trials are testing whether the broadly neutralising antibody VRC01 prevents HIV-1 infection in two cohorts: women in sub-Saharan Africa, and men and transgender persons who have sex with men (MSM/TG) in the Americas and Switzerland. We used nonlinear mixed effects modelling of longitudinal serum VRC01 concentrations to characterise pharmacokinetics and predict HIV-1 neutralisation coverage. We found that body weight significantly influenced clearance, and that the mean peripheral volume of distribution, steady state volume of distribution, elimination half-life, and accumulation ratio were significantly higher in MSM/TG than in women. Neutralisation coverage was predicted to be higher in the first (versus second) half of a given 8-week infusion interval, and appeared to be higher in MSM/TG than in women overall. Study cohort differences in pharmacokinetics and neutralisation coverage provide insights for interpreting the AMP results and for investigating how VRC01 concentration and neutralisation correlate with HIV incidence.

Molecular Epidemiology of HIV-1 in African Countries: A Comprehensive Overview

The human immunodeficiency virus type 1 (HIV-1) originated in non-human primates in West-central Africa and continues to be a major global public health issue, having claimed almost 33 million lives so far. In Africa, it is estimated that more than 20 million people are living with HIV/Acquired Immunodeficiency Syndrome (AIDS) and that more than 730,000 new HIV-1 infections still occur each year, likely due to low access to testing. The high genetic variability of HIV-1, due to a fast replication cycle and high mutation rate, may cause the generation of many viral variants in a single infected patient during a single day. Therefore, the active monitoring and characterization of the HIV-1 subtypes and recombinant forms circulating through African countries poses a significant challenge to more specific diagnoses, treatments, care, and intervention strategies. In this review, a concise characterization of all the subtypes and recombinant forms circulating in Africa is presented to highlight the magnitude of the HIV-1 threat among the African countries and to understand virus genetic diversity and dispersion dynamics better.

Emerging Role of PYHIN Proteins as Antiviral Restriction Factors

Innate immune sensors and restriction factors are cellular proteins that synergize to build an effective first line of defense against viral infections. Innate sensors are usually constitutively expressed and capable of detecting pathogen-associated molecular patterns (PAMPs) via specific pattern recognition receptors (PRRs) to stimulate the immune response. Restriction factors are frequently upregulated by interferons (IFNs) and may inhibit viral pathogens at essentially any stage of their replication cycle. Members of the Pyrin and hematopoietic interferon-inducible nuclear (HIN) domain (PYHIN) family have initially been recognized as important sensors of foreign nucleic acids and activators of the inflammasome and the IFN response. Accumulating evidence shows, however, that at least three of the four members of the human PYHIN family restrict viral pathogens independently of viral sensing and innate immune activation. In this review, we provide an overview on the role of human PYHIN proteins in the innate antiviral immune defense and on viral countermeasures.

Current and historic HIV-1 molecular epidemiology in paediatric and adult population from Kinshasa in the Democratic Republic of Congo

HIV-1 diversity may impact monitoring and vaccine development. We describe the most recent data of HIV-1 variants and their temporal trends in the Democratic Republic of Congo (DRC) from 1976 to 2018 and in Kinshasa from 1983-2018. HIV-1 pol sequencing from dried blood collected in Kinshasa during 2016-2018 was done in 340 HIV-infected children/adolescents/adults to identify HIV-1 variants by phylogenetic reconstructions. Recombination events and transmission clusters were also analyzed. Variant distribution and genetic diversity were compared to historical available pol sequences from the DRC in Los Alamos Database (LANL). We characterized 165 HIV-1 pol variants circulating in Kinshasa (2016-2018) and compared them with 2641 LANL sequences from the DRC (1976-2012) and Kinshasa (1983-2008). During 2016-2018 the main subtypes were A (26.7%), G (9.7%) and C (7.3%). Recombinants accounted for a third of infections (12.7%/23.6% Circulant/Unique Recombinant Forms). We identified the first CRF47_BF reported in Africa and four transmission clusters. A significant increase of subtype A and sub-subtype F1 and a significant reduction of sub-subtype A1 and subtype D were observed in Kinshasa during 2016-2018 compared to variants circulating in the city from 1983 to 2008. We provide unique and updated information related to HIV-1 variants currently circulating in Kinshasa, reporting the temporal trends of subtypes/CRF/URF during 43 years in the DRC, and providing the most extensive data on children/adolescents.

A Stronger Transcription Regulatory Circuit of HIV-1C Drives the Rapid Establishment of Latency with Implications for the Direct Involvement of Tat

The magnitude of transcription factor binding site variation emerging in HIV-1 subtype C (HIV-1C), especially the addition of NF-κB motifs by sequence duplication, makes the examination of transcriptional silence challenging. How can HIV-1 establish and maintain latency despite having a strong long terminal repeat (LTR)? We constructed panels of subgenomic reporter viral vectors with varying copy numbers of NF-κB motifs (0 to 4 copies) and examined the profile of latency establishment in Jurkat cells. Surprisingly, we found that the stronger the viral promoter, the faster the latency establishment. Importantly, at the time of commitment to latency and subsequent points, Tat levels in the cell were not limiting. Using highly sensitive strategies, we demonstrate the presence of Tat in the latent cell, recruited to the latent LTR. Our data allude, for the first time, to Tat establishing a negative feedback loop during the late phases of viral infection, leading to the rapid silencing of the viral promoter.IMPORTANCE Over the past 10 to 15 years, HIV-1 subtype C (HIV-1C) has been evolving rapidly toward gaining stronger transcriptional activity by sequence duplication of major transcription factor binding sites. The duplication of NF-κB motifs is unique and exclusive to HIV-1C, a property not shared with any of the other eight HIV-1 genetic families. What mechanism(s) does HIV-1C employ to establish and maintain transcriptional silence despite the presence of a strong promoter and concomitant strong, positive transcriptional feedback is the primary question that we attempted to address in the present manuscript. The role that Tat plays in latency reversal is well established. Our work with the most common HIV-1 subtype, HIV-1C, offers crucial leads toward Tat possessing a dual role in serving as both a transcriptional activator and repressor at different phases of viral infection of the cell. The leads that we offer through the present work have significant implications for HIV-1 cure research.