Dolutegravir reshapes the genetic diversity of HIV-1 reservoirs

Temporary increase in circulating replication-competent latent HIV-infected resting CD4+ T cells after switch to an integrase inhibitor based antiretroviral regimen

BACKGROUND

The principal barrier to an HIV cure is the presence of the latent viral reservoir (LVR), which has been understudied in African populations. From 2018 to 2019, Uganda instituted a nationwide rollout of ART consisting of Dolutegravir (DTG) with two NRTI, which replaced the previous regimen of one NNRTI and the same two NRTI.

METHODS

Changes in the inducible replication-competent LVR (RC-LVR) of ART-suppressed Ugandans with HIV (n = 88) from 2015 to 2020 were examined using the quantitative viral outgrowth assay. Outgrowth viruses were examined for viral evolution. Changes in the RC-LVR were analyzed using three versions of a Bayesian model that estimated the decay rate over time as a single, linear rate (model A), or allowing for a change at time of DTG initiation (model B&C).

FINDINGS

Model A estimated the slope of RC-LVR change as a non-significant positive increase, which was due to a temporary spike in the RC-LVR that occurred 0-12 months post-DTG initiation (p < 0.005). This was confirmed with models B and C; for instance, model B estimated a significant decay pre-DTG initiation with a half-life of 6.9 years, and an ∼1.7-fold increase in the size of the RC-LVR post-DTG initiation. There was no evidence of viral failure or consistent evolution in the cohort.

INTERPRETATION

These data suggest that the change from NNRTI- to DTG-based ART is associated with a significant temporary increase in the circulating RC-LVR.

FUNDING

Supported by the NIH (grant 1-UM1AI164565); Gilead HIV Cure Grants Program (90072171); Canadian Institutes of Health Research (PJT-155990); and Ontario Genomics-Canadian Statistical Sciences Institute.

Temporary increase in circulating replication-competent latent HIV-infected resting CD4+ T cells after switch to an integrase inhibitor based antiretroviral regimen

The principal barrier to an HIV cure is the presence of a latent viral reservoir (LVR) made up primarily of latently infected resting CD4+ (rCD4) T-cells. Studies in the United States have shown that the LVR decays slowly (half-life=3.8 years), but this rate in African populations has been understudied. This study examined longitudinal changes in the inducible replication competent LVR (RC-LVR) of ART-suppressed Ugandans living with HIV (n=88) from 2015-2020 using the quantitative viral outgrowth assay, which measures infectious units per million (IUPM) rCD4 T-cells. In addition, outgrowth viruses were examined with site-directed next-generation sequencing to assess for possible ongoing viral evolution. During the study period (2018-19), Uganda instituted a nationwide rollout of first-line ART consisting of Dolutegravir (DTG) with two NRTI, which replaced the previous regimen that consisted of one NNRTI and the same two NRTI. Changes in the RC-LVR were analyzed using two versions of a novel Bayesian model that estimated the decay rate over time on ART as a single, linear rate (model A) or allowing for an inflection at time of DTG initiation (model B). Model A estimated the population-level slope of RC-LVR change as a non-significant positive increase. This positive slope was due to a temporary increase in the RC-LVR that occurred 0-12 months post-DTG initiation (p<0.0001). This was confirmed with model B, which estimated a significant decay pre-DTG initiation with a half-life of 7.7 years, but a significant positive slope post-DTG initiation leading to a transient estimated doubling-time of 8.1 years. There was no evidence of viral failure in the cohort, or consistent evolution in the outgrowth sequences associated with DTG initiation. These data suggest that either the initiation of DTG, or cessation of NNRTI use, is associated with a significant temporary increase in the circulating RC-LVR.

T-Cell Receptor Repertoire Sequencing and Its Applications: Focus on Infectious Diseases and Cancer

The immune system is a dynamic feature of each individual and a footprint of our unique internal and external exposures. Indeed, the type and level of exposure to physical and biological agents shape the development and behavior of this complex and diffuse system. Many pathological conditions depend on how our immune system responds or does not respond to a pathogen or a disease or on how the regulation of immunity is altered by the disease itself. T-cells are important players in adaptive immunity and, together with B-cells, define specificity and monitor the internal and external signals that our organism perceives through its specific receptors, TCRs and BCRs, respectively. Today, high-throughput sequencing (HTS) applied to the TCR repertoire has opened a window of opportunity to disclose T-cell repertoire development and behavior down to the clonal level. Although TCR repertoire sequencing is easily accessible today, it is important to deeply understand the available technologies for choosing the best fit for the specific experimental needs and questions. Here, we provide an updated overview of TCR repertoire sequencing strategies, providers and applications to infectious diseases and cancer to guide researchers’ choice through the multitude of available options. The possibility of extending the TCR repertoire to HLA characterization will be of pivotal importance in the near future to understand how specific HLA genes shape T-cell responses in different pathological contexts and will add a level of comprehension that was unthinkable just a few years ago.

Progressive emergence of an S153F plus R263K combination of integrase mutations in the proviral DNA of one individual successfully treated with dolutegravir

OBJECTIVES

The development of HIV drug resistance against the integrase strand transfer inhibitor dolutegravir is rare. We report here the transient detection, by near full-genome ultradeep sequencing, of minority HIV-1 subtype B variants bearing the S153F and R263K integrase substitutions in the proviral DNA from blood cells of one patient who successfully initiated dolutegravir-based ART, over 24 weeks. Our objective was to study the effects of these substitutions.

METHODS

Strand transfer and DNA-binding activities of recombinant integrase proteins were measured in cell-free assays. Cell-based resistance, infectivity and replicative capacities were measured using molecular clones. Structural modelling was performed to understand experimental results.

RESULTS

R263K emerged first, followed by the addition of S153F at Week 12. By Week 24, both mutations remained present, but at lower prevalence. We confirmed the coexistence of S153F and R263K on single viral genomes. Combining S153F or S153Y with R263K decreased integration and viral replicative capacity and conferred high levels of drug resistance against all integrase inhibitors. Alone, S153Y and S153F did little to infectivity or dolutegravir resistance. We identified altered DNA binding as a mechanism of resistance. The patient remained with undetectable viral loads at all timepoints.

CONCLUSIONS

Drug-resistant minority variants have often been reported under suppressive ART. Our study adds to these observations by unravelling a progression towards higher levels of resistance through a novel pathway despite continuous undetectable viral loads. Poorly replicative HIV drug-resistant minority proviral variants did not compromise viral suppression in one individual treated with dolutegravir.

Single-cell TCR sequencing reveals phenotypically diverse clonally expanded cells harboring inducible HIV proviruses during ART

Clonal expansions occur in the persistent HIV reservoir as shown by the duplication of proviral integration sites. However, the source of the proliferation of HIV-infected cells remains unclear. Here, we analyze the TCR repertoire of single HIV-infected cells harboring translation-competent proviruses in longitudinal samples from eight individuals on antiretroviral therapy (ART). When compared to uninfected cells, the TCR repertoire of reservoir cells is heavily biased: expanded clonotypes are present in all individuals, account for the majority of reservoir cells and are often maintained over time on ART. Infected T cell clones are detected at low frequencies in the long-lived central memory compartment and overrepresented in the most differentiated memory subsets. Our results indicate that clonal expansions highly contribute to the persistence of the HIV reservoir and suggest that reservoir cells displaying a differentiated phenotype are the progeny of infected central memory cells undergoing antigen-driven clonal expansion during ART.

The cause of clonal expansions in the HIV reservoir remains unclear. Here, Gantner et al. perform single-cell TCR sequencing on longitudinal samples from eight individuals on antiretroviral therapy and find that antigens inducing clonal expansions of memory cells are major contributors to the HIV reservoir.

HIV-1 integrase resistance associated mutations and the use of dolutegravir in Sub-Saharan Africa: a systematic review and meta-analysis protocol

BACKGROUND

Sub-Saharan Africa carries the greatest burden of HIV-infection with increasing drug resistance burden, which requires improved patient management and monitoring. Current WHO recommendations suggest transitioning to dolutegravir-based (adults) or raltegravir-based-regimens (neonates) for initial antiretroviral therapy (ART) and as a suitable alternative in cases of multi-resistance in resource-limited settings. This review aims at synthesizing the current knowledge on dolutegravir use and integrase resistance-associated mutations found before the wide use of dolutegravir-based regimens.

METHODS

This systematic review will include randomized and non-randomized trials, cohort, and cross-sectional studies published on dolutegravir use or integrase resistance-associated mutations in Sub-Saharan Africa. Searches will be conducted (from 2007 onwards) in PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Latin American and Caribbean Health Sciences Literature (LILAC), Web of Science, African Journals Online, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases. Hand searching of the reference lists of relevant reviews and trials will be conducted and we will also look for conference abstracts. We will include studies of adults and/or children exposed to integrase inhibitors-based therapies; especially dolutegravir or raltegravir (which is our intervention of interest as compared to other antiretroviral regimens). We will exclude studies of patients with specific co-morbidities such as tuberculosis or opportunistic infections. Primary outcomes will be "the rate of viral suppression" and "the level of drug resistance" on integrase inhibitor-based regimens among patients in Sub-Saharan Africa. Secondary outcomes will be "the effect of baseline viremia on viral suppression," "the effect of treatment duration on viral suppression," "the proportion of patients with immune recovery," "the rate of non-adherence," "rate of adverse events;" "drug resistance according to different integrase inhibitor-based regimens," and "drug resistance according to viral subtypes/recombinants." Two reviewers will independently screen titles and abstracts, assess the full texts for eligibility, and extract data. If data permits, random effects models will be used where appropriate. Subgroup and additional analyses will be conducted to explore the potential sources of heterogeneity (e.g., age, sex, baseline viremia, CD4 following treatment, treatment duration, and adherence level).

DISCUSSION

This review will help to strengthen evidence on the effectiveness of integrase strand transfer inhibitors by contributing to current knowledge on the use of dolutegravir and/or raltegravir (especially for neonates) in Sub-Saharan Africa. Results will therefore help in setting-up baseline data for an optimal management of people living with HIV as Sub-Saharan African countries are transitioning to dolutegravir-based regimens. Evidence will also support HIV/AIDS programs in identifying gaps and actions to be undertaken for improved long-term care and treatment of people living with HIV in Sub-Saharan Africa.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019122424.

Integrase strand transfer inhibitor-based regimen is related with a limited HIV-1 V3 loop evolution in clinical practice

Integrase-strand-transfer inhibitors (INSTIs) are known to rapidly reduce HIV-1 plasma viral load, replication cycles, and new viral integrations, thus potentially limiting viral evolution. Here, we assessed the role of INSTIs on HIV-1 V3 evolution in a cohort of 89 HIV-1-infected individuals starting an INSTI- (N = 41, [dolutegravir: N = 1; elvitegravir: N = 3; raltegravir: N = 37]) or a non-INSTI-based (N = 48) combined antiretroviral therapy (cART), with two plasma RNA V3 genotypic tests available (one before [baseline] and one during cART). V3 sequences were analysed for genetic distance (Tajima-Nei model) and positive selection (dN/dS ratio). Individuals were mainly infected by B subtype (71.9%). Median (interquartile-range, IQR) plasma viral load and CD4 + T cell count at baseline were 4.8 (3.5-5.5) log₁₀ copies/mL and 207 (67-441) cells/mm³, respectively. Genetic distance (median, IQR) between the V3 sequences obtained during cART and those obtained at baseline was 0.04 (0.01-0.07). By considering treatment, genetic distance was significantly lower in INSTI-treated than in non-INSTI-treated individuals (median [IQR]: 0.03[0.01-0.04] vs. 0.05[0.02-0.08], p = 0.026). In line with this, a positive selection (defined as dN/dS ≥ 1) was observed in 36.6% of V3 sequences belonging to the INSTI-treated group and in 56.3% of non-INSTI group (p = 0.05). Multivariable logistic regression confirmed the independent correlation of INSTI-based regimens with a lower probability of both V3 evolution (adjusted odds-ratio: 0.35 [confidence interval (CI) 0.13-0.88], p = 0.027) and positive selection (even if with a trend) (adjusted odds-ratio: 0.46 [CI 0.19-1.11], p = 0.083). Overall, this study suggests a role of INSTI-based regimen in limiting HIV-1 V3 evolution over time. Further studies are required to confirm these findings.

Bictegravir in a fixed-dose tablet with emtricitabine and tenofovir alafenamide for the treatment of HIV infection: pharmacology and clinical implications

INTRODUCTION

Current antiretroviral therapy is more effective and simpler than in previous times due to the development of new drugs with improved pharmacokinetic and pharmacodynamic profiles and the advent of single pill regimens with low toxicity that facilitate long-term adherence. The recent approval of the novel potent integrase strand-transfer inhibitor bictegravir (BIC) co-formulated with emtricitabine (FTC) and tenofovir alafenamide (TAF) in a fixed daily dose pill, B/F/TAF, adds to the list of single-tablet regimens available to treat HIV infection. Areas covered: This review provides an overview of the pharmacological and clinical information obtained from MEDLINE/PubMed publications and the latest international conferences. Expert opinion: BIC is a potent antiretroviral with an improved resistance profile over previous integrase inhibitors. Its combination with the new tenofovir prodrug TAF and FTC creates an effective regimen B/F/TAF for treatment-naïve patients and for those switching from another successful combination. B/F/TAF's favorable pharmacokinetic profile, simple dose, low pill burden, and few drug-drug interactions or treatment-related adverse events, will make it one of the preferred regimens in the future.

Dolutegravir-rilpivirine: first 2-drug regimen for HIV-positive adults

INTRODUCTION

New strategies for HIV treatment are being investigated to reduce drug-exposure, toxicities, and costs. Dolutegravir (DTG) 50 mg/rilpivirine (RPV) 25 mg was approved in November 2017 by FDA and in May 2018 by the European Medicines Agency (EMA). It is indicated as a complete regimen for HIV-1 infected adults with undetectable plasmatic HIV-RNA for at least 6 months on their current HIV treatment combination. Its approval was based on the data of two randomized, multicenter, non-inferiority trials (SWORD-1 and SWORD-2). Areas covered: We reviewed data from literature about DTG and RPV. We mainly focused on the efficacy and on the safety of this new dual therapy. Its impact on renal function, its bone and cardiovascular profile, its reservoir penetration and its role on inflammation were also evaluated. Expert commentary: Dual therapies may be an attractive alternative to standard triple regimens in terms of tolerability and simplicity. Long-term efficacy of DTG and RPV dual regimen need to be confirmed, where only the extensive use of this new treatment and a longer follow-up will give us the answers.