Resistance to reverse transcriptase inhibitors used in the treatment and prevention of HIV-1 infection

Human Immunodeficiency Virus Type-1 Genetic Diversity and Drugs Resistance Mutations among People Living with HIV in Karachi, Pakistan

The human immunodeficiency virus type-1 epidemic in Pakistan has significantly increased over the last two decades. In Karachi, Pakistan, there is a lack of updated information on the complexity of HIV-1 genetic diversity and the burden of drug resistance mutations (DRMs) that can contribute to ART failure and poor treatment outcomes. This study aimed to determine HIV-1 genetic diversity and identify drug-resistance mutations among people living with HIV in Karachi. A total of 364 HIV-positive individuals, with a median age of 36 years, were enrolled in the study. The HIV-1 partial pol gene was successfully sequenced from 268 individuals. The sequences were used to generate phylogenetic trees to determine clade diversity and also to assess the burden of DRMs. Based on the partial pol sequences, 13 distinct HIV-1 subtypes and recombinant forms were identified. Subtype A1 was the most common clade (40%), followed by CRF02_AG (33.2%). Acquired DRMs were found in 30.6% of the ART-experienced patients, of whom 70.7%, 20.7%, and 8.5% were associated with resistance to NNRTIs, NRTIs, and PIs, respectively. Transmitted DRMs were found in 5.6% of the ART-naïve patients, of whom 93% were associated with resistance against NNRTIs and 7% to PIs. The high prevalence of DRMs in ART-experienced patients poses significant challenges to the long-term benefits and sustainability of the ART program. This study emphasizes the importance of continuous HIV molecular epidemiology and drug resistance surveillance to support evidence-based HIV prevention, precise ART, and targeted AIDS care.

Expanding therapeutic options: lenacapavir + bictegravir as a potential treatment for HIV

INTRODUCTION

Treatment for people with HIV/AIDS has radically evolved since the introduction of the first antiretrovirals. One newly approved antiretroviral is lenacapavir, which targets the viral capsid. Lenacapavir is currently approved as a therapeutic addition for subjects who are treatment-experienced, and who have developed resistance to multiple antiretrovirals. It is available both as a daily oral tablet and a once every 6-month subcutaneous injection. It is currently undergoing clinical trials in combination with the integrase inhibitor bictegravir as a dual therapy option, both for treatment experienced and treatment naïve individuals.

AREAS COVERED

We reviewed published articles, conference proceedings, and clinical trial databases to assess the current status of the research into lenacapavir and bictegravir. While the clinical trials are ongoing, with little published data to date, this combination shows promise for the treatment of both treatment experienced and naïve patients. We review the studies relevant to the pharmacokinetic/pharmacodynamic properties of the drugs.

EXPERT OPINION

The new combination with bictegravir will be beneficial for treatment experienced patients, as it represents a dual therapy modality with high barriers of resistance. As a therapy for treatment naïve patients, its use is likely more niche, as other combinations are available.

Identification of a Non-Nucleoside Reverse Transcriptase Inhibitor against Human Immunodeficiency Virus-1

The HIV-1 infection epidemic remains a global health problem. Current antiretroviral treatments are effective in controlling the progression of a severe infection. However, the emergence of drug resistance requires an urgent identification of new treatment regimes. HIV-1 reverse transcriptase (RTs) has been a successful therapeutic target owing to its high specificity and potent antiviral properties; therefore, it has become an essential component of current HIV-1 standard treatments. This study identified a new HIV-1 RTs inhibitor (Compound #8) that is structurally unique and greatly effective against HIV-1 through chemical library screening and a medicinal chemistry program by analyzing the structure-activity relationship (SAR). Further analysis of molecular docking and mechanisms of action demonstrated that Compound #8 is a novel type of HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI) with a flexible binding mode. Therefore, it exhibits great therapeutic potential when combined with other existing HIV-1 drugs. Our current studies suggest that Compound #8 is a promising novel scaffold for the development of new HIV-1 treatments.

Research on the Necessity of AIDS Intervention for College Students Based on Cognitive Behavioral Therapy

BACKGROUND

Despite abundant research on AIDS prevention and intervention, many residual factors influence the actual impact of the intervention at a population level. Misconceptions held by subjects lead to patterns of behavior, which do not reflect levels of cognition.

METHODS

Cognition and behavioral patterns relating to HIV were investigated without intervention in freshmen before and after a two-year study period. A total of 461 freshmen studying at the university in Wuhan, Hubei Province, China, were enrolled in September 2019. Data management and analysis were performed by SPSS 25.0 software.

RESULTS

Throughout the two years' study, no significant changes in the cognitive level regarding AIDS were found while the frequency of sexual behavior increased significantly. A trend of inconsistency between cognition and behavior was identified.

CONCLUSION

During a two-year period without intervention, it was found that the sexual behavior of university students gradually increased, perceptions regarding AIDS-related subjects were incomplete and awareness of HIV infection risk was still weak. A phenomenon described as the separation of knowledge from behavior was detected. Misconceptions that influenced behavioral patterns were identified as critical factors. Therefore, we propose that cognitive behavioral therapy may change the actual impact of AIDS prevention interventions.

Cryo-EM structures of wild-type and E138K/M184I mutant HIV-1 RT/DNA complexed with inhibitors doravirine and rilpivirine

The enzyme reverse transcriptase (RT) is a key antiviral target, and nonnucleoside RT inhibitors (NNRTIs) are among the frequently used components of antiretroviral therapy for treating HIV-1 infection. The emergence of drug-resistant mutations continues to pose a challenge in HIV treatment. The RT mutations M184I and E138K emerge in patients receiving rilpivirine. We obtained the structural snapshots of rilpivirine, doravirine, and nevirapine inhibited wild-type and M184I/E138K RT/DNA polymerase complexes by cryo-electron microscopy. Key structural changes observed in the rilpivirine- and doravirine-bound structures have implications for understanding NNRTI drug resistance. Additionally, the cryo-EM structure determination strategy outlined in this study can be adapted to aid drug design targeting smaller and flexible proteins.

Structures trapping a variety of functional and conformational states of HIV-1 reverse transcriptase (RT) have been determined by X-ray crystallography. These structures have played important roles in explaining the mechanisms of catalysis, inhibition, and drug resistance and in driving drug design. However, structures of several desired complexes of RT could not be obtained even after many crystallization or crystal soaking experiments. The ternary complexes of doravirine and rilpivirine with RT/DNA are such examples. Structural study of HIV-1 RT by single-particle cryo-electron microscopy (cryo-EM) has been challenging due to the enzyme’s relatively smaller size and higher flexibility. We optimized a protocol for rapid structure determination of RT complexes by cryo-EM and determined six structures of wild-type and E138K/M184I mutant RT/DNA in complexes with the nonnucleoside inhibitors rilpivirine, doravirine, and nevirapine. RT/DNA/rilpivirine and RT/DNA/doravirine complexes have structural differences between them and differ from the typical conformation of nonnucleoside RT inhibitor (NNRTI)–bound RT/double-stranded DNA (dsDNA), RT/RNA–DNA, and RT/dsRNA complexes; the primer grip in RT/DNA/doravirine and the YMDD motif in RT/DNA/rilpivirine have large shifts. The DNA primer 3′-end in the doravirine-bound structure is positioned at the active site, but the complex is in a nonproductive state. In the mutant RT/DNA/rilpivirine structure, I184 is stacked with the DNA such that their relative positioning can influence rilpivirine in the pocket. Simultaneously, E138K mutation opens the NNRTI-binding pocket entrance, potentially contributing to a faster rate of rilpivirine dissociation by E138K/M184I mutant RT, as reported by an earlier kinetic study. These structural differences have implications for understanding molecular mechanisms of drug resistance and for drug design.

Insights into HIV-1 Reverse Transcriptase (RT) Inhibition and Drug Resistance from Thirty Years of Structural Studies

The enzyme reverse transcriptase (RT) plays a central role in the life cycle of human immunodeficiency virus (HIV), and RT has been an important drug target. Elucidations of the RT structures trapping and detailing the enzyme at various functional and conformational states by X-ray crystallography have been instrumental for understanding RT activities, inhibition, and drug resistance. The structures have contributed to anti-HIV drug development. Currently, two classes of RT inhibitors are in clinical use. These are nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). However, the error-prone viral replication generates variants that frequently develop resistance to the available drugs, thus warranting a continued effort to seek more effective treatment options. RT also provides multiple additional potential druggable sites. Recently, the use of single-particle cryogenic electron microscopy (cryo-EM) enabled obtaining structures of NNRTI-inhibited HIV-1 RT/dsRNA initiation and RT/dsDNA elongation complexes that were unsuccessful by X-ray crystallography. The cryo-EM platform for the structural study of RT has been established to aid drug design. In this article, we review the roles of structural biology in understanding and targeting HIV RT in the past three decades and the recent structural insights of RT, using cryo-EM.

Mutation patterns, cross resistance and virological failure among HIV type-1 patients in Alexandria, Egypt

Aim: The main purpose of this cross-sectional study was to detect the prevalence of drug resistance mutations related to nonnucleoside/nucleoside reverse transcriptase inhibitors (NNRTIs/NRTIs) and protease inhibitors (PIs). Patients & methods: Patients (n = 45) with HIV type-1 were recruited, 30 of whom were treatment naive and 15 treatment experienced. A partial pol gene covering the protease/reverse transcriptase (PRRT) region was amplified and then sequenced by the Sanger method. Results & conclusion: The most common NNRTI/NRTI-related mutations were ‘V179I (24%) and K103N (14.3%)’ and ‘M41L and V75M’ (14.3% each). M36I and H69K were the most prevalent PI-related mutations (86% each). The results of the current study serve as an initial crucial step in defining the overall prevalence of HIV type-1 drug resistance in Egypt.

Current structure-based methods for designing non-nucleoside reverse transcriptase inhibitors

In 2019, structure-based methods continue to guide the design of novel antiretroviral therapies targeting HIV reverse transcriptase. This Review summarizes key findings from reverse transcriptase–non-nucleoside reverse transcriptase inhibitor analog crystal structure complexes reported from 2015 to 2019. Results from the literature and structure analysis have informed new ideas for structure-guided non-nucleoside reverse transcriptase inhibitor drug design.

Activity of Selected Nucleoside Analogue ProTides against Zika Virus in Human Neural Stem Cells

Zika virus (ZIKV), an emerging flavivirus that causes neurodevelopmental impairment to fetuses and has been linked to Guillain-Barré syndrome continues to threaten global health due to the absence of targeted prophylaxis or treatment. Nucleoside analogues are good examples of efficient anti-viral inhibitors, and prodrug strategies using phosphate masking groups (ProTides) have been employed to improve the bioavailability of ribonucleoside analogues. Here, we synthesized and tested a small library of 13 ProTides against ZIKV in human neural stem cells. Strong activity was observed for 2′-C-methyluridine and 2′-C-ethynyluridine ProTides with an aryloxyl phosphoramidate masking group. Substitution of a 2-(methylthio) ethyl phosphoramidate for the aryloxyl phosphoramidate ProTide group of 2′-C-methyluridine completely abolished antiviral activity of the compound. The aryloxyl phosphoramidate ProTide of 2′-C-methyluridine outperformed the hepatitis C virus (HCV) drug sofosbuvir in suppression of viral titers and protection from cytopathic effect, while the former compound’s triphosphate active metabolite was better incorporated by purified ZIKV NS5 polymerase over time. These findings suggest both a nucleobase and ProTide group bias for the anti-ZIKV activity of nucleoside analogue ProTides in a disease-relevant cell model.

Next-generation sequencing of HIV-1 single genome amplicons

The analysis of HIV-1 sequences has helped understand the viral molecular epidemiology, monitor the development of antiretroviral drug resistance, and design candidate vaccines. The introduction of single genome amplification (SGA) has been a major advancement in the field, allowing for the characterization of multiple sequences per patient while preserving linkage among polymorphisms in the same viral genome copy. Sequencing of SGA amplicons is performed by capillary Sanger sequencing, which presents low throughput, requires a high amount of template, and is highly sensitive to template/primer mismatching. In order to meet the increasing demand for HIV-1 SGA amplicon sequencing, we have developed a platform based on benchtop next-generation sequencing (NGS) (IonTorrent) accompanied by a bioinformatics pipeline capable of running on computer resources commonly available at research laboratories. During assay validation, the NGS-based sequencing of 10 HIV-1 env SGA amplicons was fully concordant with Sanger sequencing. The field test was conducted on plasma samples from 10 US Navy and Marine service members with recent HIV-1 infection (sampling interval: 2005–2010; plasma viral load: 5,884–194,984 copies/ml). The NGS analysis of 101 SGA amplicons (median: 10 amplicons/individual) showed within-individual viral sequence profiles expected in individuals at this disease stage, including individuals with highly homogeneous quasispecies, individuals with two highly homogeneous viral lineages, and individuals with heterogeneous viral populations. In a scalability assessment using the Ion Chef automated system, 41/43 tested env SGA amplicons (95%) multiplexed on a single Ion 318 chip showed consistent gene-wide coverage >50×. With lower sample requirements and higher throughput, this approach is suitable to support the increasing demand for high-quality and cost-effective HIV-1 sequences in fields such as molecular epidemiology, and development of preventive and therapeutic strategies.

Microwave-Assisted Expeditious Synthesis of 2-Alkyl-2-(N-arylsulfonylindol-3-yl)-3-N-acyl-5-aryl-1,3,4-oxadiazolines Catalyzed by HgCl₂ under Solvent-Free Conditions as Potential Anti-HIV-1 Agents

A series of 2-alkyl-2-(N-arylsulfonylindol-3-yl)-3-N-acyl-5-aryl-1,3,4-oxadiazolines were expeditious prepared under microwave-assisted, catalyzed by HgCl₂ and solvent-free conditions. This method has the advantage of low catalyst loading and recovering catalyst, ease reaction and repaid reaction times, easy separation products and excellent yields, and more conducive to the large-scale synthesis products. Furthermore, compounds 3s, 3y, 3a', 3b', 3f', 3i', 3q', and 3r' exhibited more potent anti-HIV-1 activity with EC50 values of 3.35, 6.12, 3.63, 9.54, 1.79, 0.51, 3.00, and 4.01 μg/mL, and TI values of 32.66, >32.68, 31.22, 13.94, 24.27, 39.59, 26.01, and 24.51, respectively. Especially compound 3i' displayed the highest anti-HIV-1 activity with TI values of 39.59.

Focus on recently developed assays for detection of resistance/sensitivity to reverse transcriptase inhibitors

The biology of HIV is rather complex due to high rate of replication, frequent recombination, and introduction of mutations. This gives rise to a number of distinct variants referred as quasispecies. In addition, the latency within reservoir allows the periodic reactivation of virus replication. The rapid replication of HIV allows immune response escape and establishment of resistance to therapy that can be acquired through drug selection and/or transmitted among individuals. This prompted, over the years, the development of a range of assays aimed to determine drug resistance and sensitivity, to be used both in clinical practice and in antiviral research. Reverse transcriptase (RT) inhibitors have an eminent place among the anti-HIV drugs, being constantly present from the beginning until today in the most commonly used antiviral regimens. This mini-review seeks to provide an up-to-date overview of recent efforts in developing even more reliable and simple methods, of both genotypic and phenotypic types, for specifically detecting drug resistance and sensitivity to RT inhibitors.

Antiretroviral resistance in HIV-1 patients at a tertiary medical institute in Saudi Arabia: a retrospective study and analysis

Background

Since the early 90’s antiretroviral drugs have been available at King Faisal Specialist Hospital and Research Centre (KFSH&RC), a referral hospital in Riyadh, Saudi Arabia, for the treatment of both adults and children infected with HIV-1. However, up to date, there are no genetic profiling data for the resistance-causing mutations in HIV-1 virus in patients on antiretroviral drugs therapy. This paper presents an initial report and a profiling survey of drug resistance-associated mutations of 103 HIV-1 patients seen at KFSH&RC.

Methods

This is a retrospective study on Patients treated at KFSH&RC since 2003 up to 2016. The analysis was done on the drug resistance mutations profiles of 103 patients who were undergoing highly active antiretroviral therapy protocols.

Results

Our analysis shows that the drug resistance mutations reported in our treatment cohort of HIV-infected adults patients is similar what is internationally reported to some extent. Additionally, we have identified novel drug resistance causing mutations. Furthermore, different profile of drug resistance causing mutations was also observed.

Conclusion

Patients showed both similar and new drug resistant causing mutations, early identification of these mutations is crucial to guide and avoid failure future therapy.

Emergence of resistance mutations in simian immunodeficiency virus (SIV)-infected rhesus macaques receiving non-suppressive antiretroviral therapy (ART)

Two SIVmac251-infected rhesus macaques received tenofovir/emtricitabine with raltegravir intensification. Viral rebound occurred during treatment and sequencing of reverse transcriptase and integrase genes identified multiple resistance mutations. Similar to HIV infection, antiretroviral-resistance mutations may occur in SIV-infected nonhuman primates receiving nonsuppressive ART. As ART administration to nonhuman primates is currently dramatically expanding, fueled by both cure research and the study of HIV-related comorbidities, viral resistance should be factored in the study design and data interpretation.

Validation and implementation of liquid chromatographic-mass spectrometric (LC-MS) methods for the quantification of tenofovir prodrugs

BACKGROUND

The nucleotide reverse transcriptase inhibitor tenofovir (TFV) is widely administered in a disoproxil prodrug form (tenofovir disoproxil fumarate, TDF) for HIV management and prevention. Recently, novel prodrugs tenofovir alafenamide fumarate (TAF) and hexadecyloxypropyl tenofovir (CMX157) have been pursued for HIV treatment while minimizing adverse effects associated with systemic TFV exposure. Dynamic and sensitive bioanalytical tools are required to characterize the pharmacokinetics of these prodrugs in systemic circulation. Two parallel methods have been developed, one to combinatorially quantify TAF and TFV, and a second method for CMX157 quantification, in plasma.

METHODS

K₂EDTA plasma was spiked with TAF and TFV, or CMX157. Following the addition of isotopically labeled internal standards and sample extraction via solid phase extraction (TAF and TFV) or protein precipitation (CMX157), samples were subjected to liquid chromatographic-tandem mass spectrometric (LC-MS/MS) analysis. For TAF and TFV, separation occurred using a Zorbax Eclipse Plus C18 Narrow Bore RR, 2.1 × 50 mm, 3.5 μm column and analytes were detected on an API5000 mass analyzer; CMX157 was separated using a Kinetex C8, 2.1 × 50 mm, 2.6 μm column and quantified using an API4500 mass spectrometer. Methods were validated according to FDA Bioanalytical Method Validation guidelines.

RESULTS

Analytical methods: were optimized for the multiplexed monitoring of TAF and TFV, and CMX157 in plasma. The lower limits of quantification (LLOQs) for TAF, TFV, and CMX157 were 0.03, 1.0, and 0.25 ng/mL, respectively. Calibration curves were generated via weighted linear regression of standards. Intra- and inter-assay precision and accuracy studies demonstrated %CVs ≤ 14.4% and %DEVs ≤ ± 7.95%, respectively. Stability and matrix effects studies were also performed. All results were acceptable and in accordance with the recommended guidelines for bioanalytical methods. Assays were also applied to quantify in vivo concentrations of prodrugs and TFV in a preclinical study post-rectal administration.

CONCLUSIONS

Sensitive, specific, and dynamic LC-MS/MS assays have been developed and validated for the multiplexed quantification TAF and TFV, as well as an independent assay for CMX157 quantification, in plasma. The described methods meet sufficient throughput criteria to support large research trials.

Decoding HIV resistance: from genotype to therapy

Genetic variation in HIV poses a major challenge for prevention and treatment of the AIDS pandemic. Resistance occurs by mutations in the target proteins that lower affinity for the drug or alter the protein dynamics, thereby enabling viral replication in the presence of the drug. Due to the prevalence of drug-resistant strains, monitoring the genotype of the infecting virus is recommended. Computational approaches for predicting resistance from genotype data and guiding therapy are discussed. Many prediction methods rely on rules derived from known resistance-associated mutations, however, statistical or machine learning can improve the classification accuracy and assess unknown mutations. Adding classifiers such as information on the atomic structure of the protein can further enhance the predictions.

Nevirapine induced mitochondrial dysfunction in HepG2 cells

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor frequently used in combination with other antiretroviral agents for highly active antiretroviral therapy (HAART) of patients infected with the human immunodeficiency virus type 1 (HIV-1). However NVP can cause serious, life-threatening complications. Hepatotoxicity is one of the most severe adverse effects, particularly in HIV patients with chronic hepatitis C virus co-infection as these patients can develop liver toxicity after a relatively short course of treatment. However, the mechanism of NVP-associated hepatotoxicity remains unclear. This study sought to investigate the effect of NVP on protein expression in liver cells using a proteomic approach. HepG2 cells were treated or not treated with NVP and proteins were subsequently resolved by two-dimensional gel electrophoresis. A total of 33 differentially regulated proteins were identified, of which nearly 40% (13/33) were mitochondrial proteins. While no obvious differences were observed between NVP treated and untreated cells after staining mitochondria with mitotracker, RT-PCR expression analysis of three mitochondrially encoded genes showed all were significantly up-regulated in NVP treated cells. Mitochondrial dysfunction was observed in response to treatment even with slightly sub-optimal therapeutic treatment concentrations of NVP. This study shows that NVP induces mitochondrial dysregulation in HepG2 cells.

Rilpivirine use in the Swiss HIV cohort study: a prospective cohort study

Background

Rilpivirine is safe and effective in HIV-naïve patients with low baseline HIV-RNA or in switch strategy. It offers the advantages of few drug-drug interactions and a favourable toxicity profile. We aimed to determine the reasons for prescribing the rilpivirine (RPV)/tenofovir disoproxil (TDF)/emtricitabine (FTC) co-formulation within the Swiss HIV Cohort Study and to assess its effectiveness and safety over a 24 months period.

Methods

All individuals enrolled in the Swiss HIV Cohort Study who initiated a RPV/TDF/FTC co-formulation between April 2013 and March 2014 were included. Primary outcomes were the HIV-RNA viral load (copies/mL) and CD4 cell count (cells/mm³) at 6, 12 and 24 months. Reasons for a switch to RPV/TDF/FTC were evaluated through a standardized questionnaire. We also assessed discontinuation and reasons for discontinuation of RPV/TDF/FTC until October 30, 2015.

Results

Of 644 individuals who started the RPV/TDF/FTC co-formulation, only 7.5% were treatment-naïve. At 24 months, viral suppression (HIV-RNA <50 copies/mL) was achieved in 100% and 96.7% of cART-naïve and cART-experienced patients respectively. The switch to RPV was mainly done for simplification (44.6%) and to overcome central nervous system toxicity symptoms due to efavirenz (24%). Six months after switch, 74.8% of patients reported an improvement of psycho-neurological symptoms with continued improvement at 12 months for almost 80%. However, one quarter of patients reported a discontinuation of RPV/TDF/FTC on October 30, 2015 after a median time of 18.4 months. Reasons for discontinuation included physician decision (5.3%) and side-effects (3.9%) mainly related to the central nervous system and to renal toxicity.

Conclusion

The RPV/TDF/FTC co-formulation was safe and effective throughout 24 months of follow-up but barely prescribed for HIV-naïve patients. Despite excellent virological suppression among both treatment-naïve and -experienced patients, we observed a high rate of treatment discontinuation.

How to win the HIV-1 drug resistance hurdle race: running faster or jumping higher?

Infections by the human immunodeficiency virus type 1 (HIV-1), the causative agent of the acquired immunodeficiency syndrome (AIDS), are still totaling an appalling 36.7 millions worldwide, with 1.1 million AIDS deaths/year and a similar number of yearly new infections. All this, in spite of the discovery of HIV-1 as the AIDS etiological agent more than 30 years ago and the introduction of an effective combinatorial antiretroviral therapy (cART), able to control disease progression, more than 20 years ago. Although very effective, current cART is plagued by the emergence of drug-resistant viral variants and most of the efforts in the development of novel direct-acting antiviral agents (DAAs) against HIV-1 have been devoted toward the fighting of resistance. In this review, rather than providing a detailed listing of all the drugs and the corresponding resistance mutations, we aim, through relevant examples, at presenting to the general reader the conceptual shift in the approaches that are being taken to overcome the viral resistance hurdle. From the classic 'running faster' strategy, based on the development of novel DAAs active against the mutant viruses selected by the previous drugs and/or presenting to the virus a high genetic barrier toward the development of resilience, to a 'jumping higher' approach, which looks at the cell, rather than the virus, as a source of valuable drug targets, in order to make the cellular environment non-permissive toward the replication of both wild-type and mutated viruses.

Isatin thiazoline hybrids as dual inhibitors of HIV-1 reverse transcriptase

A series of 3-3-{2-[2-3-methyl-4-phenyl-2,3-dihydro-1,3-thiazol-2-ylidene]hydrazin-1-ylidene-2,3-dihydro-1H-indol-2-one derivatives has been designed and synthesized to study their activity on both HIV-1 (Human Immunodeficiency Virus type 1) RT (Reverse Transcriptase) associated functions. These derivatives are analogs of previously reported series whose biological activity and mode of action have been investigated. In this work we investigated the influence of the introduction of a methyl group in the position 3 of the dihydrothiazole ring and of a chlorine atom in the position 5 of the isatin nucleus. The new synthesized compounds are active towards both DNA polymerase and ribonuclease H in the µM range. The nature of the aromatic group in the position 4 of the thiazole was relevant in determining the biological activity.

Pre-exposure prophylaxis: a useful tool to prevent human immunodeficiency virus infection?

The aim of preventive measures against human immunodeficiency virus (HIV) is to reduce the incidence of HIV infection in the general population and in high-risk groups, such as men having sex with men (MSM), and to reduce the risk that a given individual will contract or spread the virus. Male and female condoms, post-exposure prophylaxis and circumcision are preventive methods currently recognized or promoted worldwide. Although modest success has been reported in a phase-III vaccine trial, other methods are being evaluated, such as vaginal and rectal microbicides, and pre-exposure prophylaxis (PrEP). Herein, we discuss results from prevention trials, especially those focusing on PrEP and particularly on recent results from 'on-demand' PrEP regimens. The efficacy of PrEP (rates of 0%-86%) is strongly correlated with adherence and plasma concentrations of antiretrovirals. Adverse events are rare. Selection of emtricitabine-resistant strains is mainly reported in individuals with an undiagnosed HIV infection using PrEP. PrEP is now strongly recommended in WHO prevention programmes for individuals at substantial risk for HIV with a view to controlling this epidemic by 2030.

Discovery, characterization, and lead optimization of 7-azaindole non-nucleoside HIV-1 reverse transcriptase inhibitors

A library of 585 compounds built off a 7-azaindole core was evaluated for anti-HIV-1 activity, and ten hits emerged with submicromolar potency and therapeutic index >100. Of these, three were identified as non-nucleoside reverse transcriptase (RT) inhibitors and were assayed against relevant resistant mutants. Lead compound 8 inhibited RT with submicromolar potency (IC50=0.73μM) and also maintained some activity against the clinically important RT mutants K103N and Y181C (IC50=9.2, 3.5μM) in cell-free assays. Free energy perturbation guided lead optimization resulted in the development of a compound with a two-fold increase in potency against RT (IC50=0.36μM). These data highlight the discovery of a unique scaffold with the potential to move forward as next-generation anti-HIV-1 agents.

Effect on HIV-1 viral replication capacity of DTG-resistance mutations in NRTI/NNRTI resistant viruses

Background

Recommended regimens for HIV-positive individuals include the co-administration of dolutegravir (DTG) with two reverse transcriptase inhibitors (RTIs). Although rare, emerging resistance against DTG is often associated with the R263K substitution in integrase. In-vitro-selected R263K was associated with impaired viral replication capacity, DNA integration, and integrase strand-transfer activity, especially when accompanied by the secondary mutation H51Y. Given the reduced fitness of RTI-resistant viruses, we investigated potential impacts on viral replication of combining R263K and H51Y/R263K with major RTI-resistance substitutions including K65R, L74V, K103N, E138K, and M184I/V.

Results

We combined the R263K or H51Y/R263K with RTI-resistance mutations into the proviral plasmid pNL4.3 and measured the resulting viral infectiousness, replication capacity, and ability to integrate viral DNA into host cells. Infectiousness was determined by luciferase assay in TZM-bl cells. Replicative capacity was monitored over 7 days and viral DNA integration was studied by real-time Alu-qPCR in PM1 cells. We found that viral infectiousness, replication capacities and integration levels were greatly reduced in triple mutants, i.e. H51Y/R263K plus a RT mutation, and moderately reduced in double mutants, i.e. R263K plus a RT mutation, compared to wild-type and single RT-mutant viruses.

Conclusions

Our findings help to explain the absence of RTI mutations in individuals who experienced DTG-treatment failure.