Current and emerging non-nucleoside reverse transcriptase inhibitors (NNRTIs) for HIV-1 treatment

Unachieved antiviral strategies with acyclic nucleoside phosphonates: Dedicated to the memory of dr. Salvatore "Sam" Joseph Enna

Many acyclic nucleoside phosphonates such as cidofovir, adefovir dipivoxil, tenofovir disoproxil fumarate, and tenofovir alafenamide have been marketed for the treatment or prophylaxis of infectious diseases. Here, this review highlights potent acyclic nucleoside phosphonates for their potential in the treatment of retrovirus (e.g., human immunodeficiency virus) and DNA virus (e.g., adeno-, papilloma-, herpes- and poxvirus) infections. If properly assessed and/or optimized, some potent acyclic nucleoside phosphonates can be possibly applied in the control of current and emerging infectious diseases.

Design and optimization of piperidine-substituted thiophene[3,2-d]pyrimidine-based HIV-1 NNRTIs with improved drug resistance and pharmacokinetic profiles

HIV-1 reverse transcriptase (RT) has received great attention as an attractive therapeutic target for acquired immune deficiency syndrome (AIDS), but the inevitable drug resistance and side effects have always been major challenges faced by non-nucleoside reverse transcriptase inhibitors (NNRTIs). This work aimed to identify novel chemotypes of anti-HIV-1 agents with improved drug-resistance profiles, reduced toxicity, and excellent druggability. A series of diarylpyrimidine (DAPY) derivatives were prepared via structural modifications of the leads K-5a2 and 25a. Among them, 15a with dimethylphosphine oxide moiety showed the most prominent antiviral potency against all of the tested viral panel, being 1.6-fold (WT, EC50 = 1.75 nmol/L), 3.0-fold (L100I, EC50 = 2.84 nmol/L), 2.4-fold (K103N, EC50 = 1.27 nmol/L), 3.3-fold (Y181C, EC50 = 5.38 nmol/L), 2.9-fold (Y188L, EC50 = 7.96 nmol/L), 2.5-fold (E138K, EC50 = 4.28 nmol/L), 4.8-fold (F227L/V106A, EC50 = 3.76 nmol/L) and 5.3-fold (RES056, EC50 = 15.8 nmol/L) more effective than that of the marketed drug ETR. Molecular docking results illustrated the detailed interactions formed by compound 15a and WT, F227L/V106A, and RES056 RT. Moreover, 15a·HCl carried outstanding pharmacokinetic (t 1/2 = 1.32 h, F = 40.8%) and safety profiles (LD50 > 2000 mg/kg), which demonstrated that 15a HCl is a potential anti-HIV-1 drug candidate.

Artificial intelligence-driven drug repositioning uncovers efavirenz as a modulator of α-synuclein propagation: Implications in Parkinson's disease

Parkinson's disease (PD) is a complex neurodegenerative disorder with an unclear etiology. Despite significant research efforts, developing disease-modifying treatments for PD remains a major unmet medical need. Notably, drug repositioning is becoming an increasingly attractive direction in drug discovery, and computational approaches offer a relatively quick and resource-saving method for identifying testable hypotheses that promote drug repositioning. We used an artificial intelligence (AI)-based drug repositioning strategy to screen an extensive compound library and identify potential therapeutic agents for PD. Our AI-driven analysis revealed that efavirenz and nevirapine, approved for treating human immunodeficiency virus infection, had distinct profiles, suggesting their potential effects on PD pathophysiology. Among these, efavirenz attenuated α-synuclein (α-syn) propagation and associated neuroinflammation in the brain of preformed α-syn fibrils-injected A53T α-syn Tg mice and α-syn propagation and associated behavioral changes in the C. elegans BiFC model. Through in-depth molecular investigations, we found that efavirenz can modulate cholesterol metabolism and mitigate α-syn propagation, a key pathological feature implicated in PD progression by regulating CYP46A1. This study opens new avenues for further investigation into the mechanisms underlying PD pathology and the exploration of additional drug candidates using advanced computational methodologies.

The Phenomenon of Antiretroviral Drug Resistance in the Context of Human Immunodeficiency Virus Treatment: Dynamic and Ever Evolving Subject Matter

Human immunodeficiency virus (HIV) is a significant global health issue that affects a substantial number of individuals across the globe, with a total of 39 million individuals living with HIV/AIDS. ART has resulted in a reduction in HIV-related mortality. Nevertheless, the issue of medication resistance is a significant obstacle in the management of HIV/AIDS. The unique genetic composition of HIV enables it to undergo rapid mutations and adapt, leading to the emergence of drug-resistant forms. The development of drug resistance can be attributed to various circumstances, including noncompliance with treatment regimens, insufficient dosage, interactions between drugs, viral mutations, preexposure prophylactics, and transmission from mother to child. It is therefore essential to comprehend the molecular components of HIV and the mechanisms of antiretroviral medications to devise efficacious treatment options for HIV/AIDS.

Pharmacological advances in anti-retroviral therapy for human immunodeficiency virus-1 infection: A comprehensive review

The discovery of anti-retroviral (ARV) drugs over the past 36 years has introduced various classes, including nucleoside/nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, protease inhibitor, fusion, and integrase strand transfer inhibitors inhibitors. The introduction of combined highly active anti-retroviral therapies in 1996 was later proven to combat further ARV drug resistance along with enhancing human immunodeficiency virus (HIV) suppression. As though the development of ARV therapies was continuously expanding, the variation of action caused by ARV drugs, along with its current updates, was not comprehensively discussed, particularly for HIV-1 infection. Thus, a range of HIV-1 ARV medications is covered in this review, including new developments in ARV therapy based on the drug's mechanism of action, the challenges related to HIV-1, and the need for combination therapy. Optimistically, this article will consolidate the overall updates of HIV-1 ARV treatments and conclude the significance of HIV-1-related pharmacotherapy research to combat the global threat of HIV infection.

Current insights and molecular docking studies of HIV-1 reverse transcriptase inhibitors

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS), a lethal disease that is prevalent worldwide. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) data, 38.4 million people worldwide were living with HIV in 2021. Viral reverse transcriptase (RT) is an excellent target for drug intervention. Nucleoside reverse transcriptase inhibitors (NRTIs) were the first class of approved antiretroviral drugs. Later, a new type of non-nucleoside reverse transcriptase inhibitors (NNRTIs) were approved as anti-HIV drugs. Zidovudine, didanosine, and stavudine are FDA-approved NRTIs, while nevirapine, efavirenz, and delavirdine are FDA-approved NNRTIs. Several agents are in clinical trials, including apricitabine, racivir, elvucitabine, doravirine, dapivirine, and elsulfavirine. This review addresses HIV-1 structure, replication cycle, reverse transcription, and HIV drug targets. This study focuses on NRTIs and NNRTIs, their binding sites, mechanisms of action, FDA-approved drugs and drugs in clinical trials, their resistance and adverse effects, their molecular docking studies, and highly active antiretroviral therapy (HAART).

Efficacy, Safety, and Tolerability of Doravirine/Lamivudine/Tenofovir Disoproxil Fumarate Fixed-Dose Combination Tablets in Adolescents Living With HIV: Results Through Week 96 from IMPAACT 2014

BACKGROUND

IMPAACT 2014 study is a phase I/II, multicenter, open-label, nonrandomized study of doravirine (DOR) co-formulated with lamivudine (3TC) and tenofovir disoproxil fumarate (TDF) as fixed-dose combination (DOR FDC) in adolescents with HIV-1. We report the efficacy, safety, and tolerability of DOR FDC through 96 weeks.

METHODS

Participants were adolescents aged 12 to <18 years who weighed at least 45 kg and who were either antiretroviral (ARV)-naïve or virologically suppressed without documented resistance mutations to DOR/3TC/TDF. The efficacy endpoint was the proportion of participants with HIV-1 RNA <40 copies/mL assessed at weeks 48 and 96 using the observed failure approach. Safety and tolerability outcomes were incidence of adverse events (AEs) and treatment discontinuations.

RESULTS

A total of 45 adolescents, median age 15 (range, 12-17) years, 58% females, were enrolled and 2 (4.4%) participants were ARV naïve. Of the 45 participants, 42 (93.3%) completed the study and 41 (91.1%) completed the study treatment. At week 48, 41/42 (97.6%; 95% confidence interval [CI], 87.4-99.9) and week 96, 37/40 (92.5%; 95% CI, 79.6-98.4) participants had achieved or maintained HIV-1 RNA <40 copies/mL. There were no treatment-related discontinuations due to AEs and no drug-related AEs ≥grade 3 or deaths.

CONCLUSIONS

We found once-daily dosing of DOR FDC to be safe and well tolerated for maintaining viral suppression through 96 weeks in adolescents living with HIV-1.

Factors Associated with Virological Failure in First-Line Antiretroviral Therapy in Patients Diagnosed with HIV-1 between 2010 and 2018 in Israel

Despite the progress in contemporary antiretroviral therapy (ART) and the continuous changes in treatment guidelines, virological failure (VF) is still an ongoing concern. The goal of this study was to assess factors related to VF after first-line ART. A longitudinal cohort retrospective study of individuals on first-line ART diagnosed with HIV-1 in 2010-2018 and followed-up for a median of two years was conducted. Demographics, baseline and longitudinal CD4 counts, treatment regimens, adherence and VF were recorded. The Cox proportional hazards regression and mixed models were used. A cohort of 1130 patients were included. Overall, 80% were males and 62% were Israeli-born individuals. Compared to individuals diagnosed in 2010-2014, when treatment was initiated according to CD4 levels, those diagnosed in 2015-2018 were older and had lower baseline CD4 counts. VF was recorded in 66 (5.8%) patients. Diagnosis with CD4 <200 cells/mmᶟ with AIDS-defining conditions (HR = 2.75, 95%CI:1.52-4.97, p < 0.001) and non-integrase strand transfer inhibitor regimens (non-INSTI, HR = 1.80, 95%CI:1.01-3.24, p = 0.047) increased VF risk. No impact of baseline resistance was observed. We concluded that the early detection of HIV-1 infection and usage of INSTI-based regimens are recommended to reduce VF.

Current drugs for HIV-1: from challenges to potential in HIV/AIDS

The human immunodeficiency virus (HIV) persists in latently infected CD4+T cells and integrates with the host genome until cell death. Acquired immunodeficiency syndrome (AIDS) is associated with HIV-1. Possibly, treating HIV/AIDS is an essential but challenging clinical goal. This review provides a detailed account of the types and mechanisms of monotherapy and combination therapy against HIV-1 and describes nanoparticle and hydrogel delivery systems. In particular, the recently developed capsid inhibitor (Lenacapavir) and the Ainuovirine/tenofovir disoproxil fumarate/lamivudine combination (ACC008) are described. It is interestingly to note that the lack of the multipass transmembrane proteins serine incorporator 3 (SERINC3) and the multipass transmembrane proteins serine incorporator 5 (SERINC5) may be one of the reasons for the enhanced infectivity of HIV-1. This discovery of SERINC3 and SERINC5 provides new ideas for HIV-1 medication development. Therefore, we believe that in treating AIDS, antiviral medications should be rationally selected for pre-exposure and post-exposure prophylaxis to avoid the emergence of drug resistance. Attention should be paid to the research and development of new drugs to predict HIV mutations as accurately as possible and to develop immune antibodies to provide multiple guarantees for the cure of AIDS.

Exploring antiviral potency of N-1 substituted pyrimidines against HIV-1 and other DNA/RNA viruses: Design, synthesis, characterization, ADMET analysis, docking, molecular dynamics and biological activity

A novel series of pyrimidine derivatives, bearing modified benzimidazoles at N-1 position, has been designed, synthesized and screened as NNRTIs against HIV and as broad-spectrum antiviral agents. The molecules were screened against different HIV targets using molecular docking experiment. The docking results indicated that the molecules interacted well with the residues Lys101, Tyr181, Tyr188, Trp229, Phe227 and Tyr318 present in NNIBP of HIV-RT protein, formed quite stable complexes and, thus, behaved as probable NNRTIs. Among these compounds, 2b and 4b showed anti-HIV activity with IC50 values as 6.65 µg/mL (SI = 15.50) and 15.82 µg/mL (SI = 14.26), respectively. Similarly, compound 1a showed inhibitory property against coxsackie virus B4 and compound 3b against different viruses. Molecular dynamics simulation results unequivocally demonstrated the higher stability of the complex HIV-RT:2b than the HIV-RT:nevirapine complex. The MM/PBSA-based binding free energy (-) 114.92 kJ/mol of HIV-RT:2b complex in comparison to that of HIV-RT:nevirapine complex (-) 88.33 kJ/mol, further demonstrated the higher binding strength of 2b and thus, established the potential of compound 2b as a lead molecule as an HIV-RT inhibitor.

Strategies in the Design and Development of Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

AIDS (acquired immunodeficiency syndrome) is a potentially life-threatening infectious disease caused by human immunodeficiency virus (HIV). To date, thousands of people have lost their lives annually due to HIV infection, and it continues to be a big public health issue globally. Since the discovery of the first drug, Zidovudine (AZT), a nucleoside reverse transcriptase inhibitor (NRTI), to date, 30 drugs have been approved by the FDA, primarily targeting reverse transcriptase, integrase, and/or protease enzymes. The majority of these drugs target the catalytic and allosteric sites of the HIV enzyme reverse transcriptase. Compared to the NRTI family of drugs, the diverse chemical class of non-nucleoside reverse transcriptase inhibitors (NNRTIs) has special anti-HIV activity with high specificity and low toxicity. However, current clinical usage of NRTI and NNRTI drugs has limited therapeutic value due to their adverse drug reactions and the emergence of multidrug-resistant (MDR) strains. To overcome drug resistance and efficacy issues, combination therapy is widely prescribed for HIV patients. Combination antiretroviral therapy (cART) includes more than one antiretroviral agent targeting two or more enzymes in the life cycle of the virus. Medicinal chemistry researchers apply different optimization strategies including structure- and fragment-based drug design, prodrug approach, scaffold hopping, molecular/fragment hybridization, bioisosterism, high-throughput screening, covalent-binding, targeting highly hydrophobic channel, targeting dual site, and multi-target-directed ligand to identify and develop novel NNRTIs with high antiviral activity against wild-type (WT) and mutant strains. The formulation experts design various delivery systems with single or combination therapies and long-acting regimens of NNRTIs to improve pharmacokinetic profiles and provide sustained therapeutic effects.

Clinical spectrum and currently available treatment of type I interferonopathy Aicardi-Goutières syndrome

BACKGROUND

Aicardi-Goutières syndrome (AGS) is a genetically determined disorder with a variable phenotype. Since the original description of AGS, advances in gene sequencing techniques have resulted in a significant broadening of the phenotypic spectrum associated with AGS genes, and new clinical pictures have emerged beyond the classic presentation. The aim of this review is to provide a comprehensive analysis of the clinical spectrum of AGS and report currently available treatments and new immunosuppressive strategies.

DATA SOURCES

Literature reviews and original research articles were collected from databases, including PubMed and ClinicalTrials.gov. Relevant articles about AGS were included.

RESULTS

The involvement of the nervous system certainly represents the major cause of mortality and morbidity in AGS patients. However, other clinical manifestations, such as chilblains, hepatosplenomegaly, and hematological disturbances, may lead to the diagnosis and considerably impact the prognosis and overall quality of life of these patients. Therapeutic approaches of AGS are limited to interventions aimed at specific symptoms and the management of multiple comorbidities. However, advances in understanding the pathogenesis of AGS could open new and more effective therapies.

CONCLUSIONS

The over-activation of innate immunity due to upregulated interferon production plays a critical role in AGS, leading to multi-organ damage with the main involvement of the central nervous system. To date, there is no specific and effective treatment for AGS. New drugs specifically targeting the interferon pathway may bring new hope to AGS patients.

Discovery of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles as potent HIV-1 NNRTIs with improved anti-resistance and drug-like profiles

Taking our previously reported HIV-1 NNRTIs BH-11c and XJ-10c as lead compounds, series of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles were designed to improve anti-resistance and drug-like profiles. According to the three rounds of in vitro antiviral activity screening, compound 12g was the most active inhibitor against wild-type and five prevalent NNRTI-resistant HIV-1 strains with EC₅₀ values ranging from 0.024 to 0.0010 μM. This is obviously better than the lead compound BH-11c and the approved drug ETR. Detailed structure-activity relationship was investigated to provide valuable guidance for further optimization. The MD simulation study indicated that 12g could form additional interactions with residues around the binding site in HIV-1 RT, which provided reasonable explanations for its improved anti-resistance profile compared to ETR. Furthermore, 12g showed significant improvement in water solubility and other drug-like properties compared to ETR. The CYP enzymatic inhibitory assay indicated that 12g was unlikely to induce CYP-mediated drug-drug interactions. 12g pharmacokinetics parameters were investigated and it displayed a long half-life of 6.59 h in vivo. The properties of compound 12g make it a promising lead compound for the development of new generation of antiretroviral drugs.

Discovery of diarylpyrimidine derivatives bearing piperazine sulfonyl as potent HIV-1 nonnucleoside reverse transcriptase inhibitors

HIV-1 reverse transcriptase is one of the most attractive targets for the treatment of AIDS. However, the rapid emergence of drug-resistant strains and unsatisfactory drug-like properties seriously limit the clinical application of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Here we show that a series of piperazine sulfonyl-bearing diarylpyrimidine-based NNRTIs were designed to improve the potency against wild-type and NNRTI-resistant strains by enhancing backbone-binding interactions. Among them, compound 18b1 demonstrates single-digit nanomolar potency against the wild-type and five mutant HIV-1 strains, which is significantly better than the approved drug etravirine. The co-crystal structure analysis and molecular dynamics simulation studies were conducted to explain the broad-spectrum inhibitory activity of 18b1 against reverse transcriptase variants. Besides, compound 18b1 demonstrates improved water solubility, cytochrome P450 liability, and other pharmacokinetic properties compared to the currently approved diarylpyrimidine (DAPY) NNRTIs. Therefore, we consider compound 18b1 a potential lead compound worthy of further study.

Tracing the recent updates on vaccination approaches and significant adjuvants being developed against HIV

INTRODUCTION

Human Immunodeficiency Virus type 1 (HIV1); the causative agent of Acquired Immunodeficiency Syndrome (AIDS), has been a major target of the scientific community to develop an anti-viral therapy. Some successful discoveries have been made during the last two decades in the form of availability of antiviral therapy in endemic regions. Nevertheless, a total cure and safety vaccine has not yet been designed to eradicate HIV from the world.

AREAS COVERED

The purpose of this comprehensive study is to compile recent data regarding therapeutic interventions against HIV and to determine future research needs in this field. A systematic research strategy has been used to gather data from recent, most advanced published electronic sources. Literature based results show that experiments at the invitro level and animal models are continuously in research annals and are providing hope for human trials.

EXPERT OPINION

There is still a gap and more work is needed in the direction of modern drug and vaccination designs. Moreover coordination is necessary among researchers, educationists, public health workers, and the general community to communicate and coordinate the repercussions associated with the deadly disease. It is important for taking timely measures regarding mitigation and adaptation with HIV in future.

Various strategies for developing APOBEC3G protectors to circumvent human immunodeficiency virus type 1

Host restriction factor APOBEC3G (A3G) efficiently restricts Vif-deficient HIV-1 by being packaged with progeny virions and causing the G to A mutation during HIV-1 viral DNA synthesis as the progeny virus infects new cells. HIV-1 expresses Vif protein to resist the activity of A3G by mediating A3G degradation. This process requires the self-association of Vif in concert with A3G proteins, protein chaperones, and factors of the ubiquitination machinery, which are potential targets to discover novel anti-HIV drugs. This review will describe compounds that have been reported so far to inhibit viral replication of HIV-1 by protecting A3G from Vif-mediated degradation.

Residual phenotypic susceptibility to doravirine in multidrug-resistant HIV-1 from subjects enrolled in the PRESTIGIO Registry

OBJECTIVES

Doravirine shows a rather distinct resistance profile within the nonnucleoside reverse transcriptase inhibitor (NNRTI) class. This study aimed to evaluate the phenotypic susceptibility to doravirine, rilpivirine and etravirine in a panel of multidrug-resistant (MDR) HIV-1 isolates collected from people living with HIV (PLWH) enrolled in the PRESTIGIO Registry.

METHODS

Recombinant viruses expressing PLWH-derived protease, reverse transcriptase coding regions were generated from plasma samples at virological failure with documented resistance to protease inhibitors, nucleoside reverse transcriptase inhibitors, NNRTIs and integrase strand transfer inhibitors. In vitro susceptibility was assessed through a phenotypic assay measuring fold-change values with respect to the reference NL4-3 virus. Genotypic susceptibility was computed by the Stanford HIVdb algorithm 8.9-1.

RESULTS

Plasma samples were collected from 22 PLWH: 20 (91%) were male, median age 55 years (IQR 50-58), time since HIV-1 diagnosis 27 years (23-31) and time on antiretroviral treatment 23 years (22-26). Median doravirine, etravirine and rilpivirine fold-change values were 9.8 (2.9-40.4), 42.9 (3.1-100.0) and 100.0 (17.9-100.0), respectively. According to the fold-change cut-offs, full susceptibility was observed in five (23%), four (18%) and one (5%) cases with doravirine, etravirine and rilpivirine, respectively. Irrespective of the presence of specific doravirine mutations, higher numbers of NNRTI mutations correlated with higher fold-change values for doravirine. By comparing the distribution of fold-change values with the Stanford HIVdb predicted susceptibility, a significant correlation was detected for doravirine and rilpivirine but not etravirine.

CONCLUSION

Despite extensive cross-resistance among NNRTIs, doravirine can be a valid option in a proportion of PLWH with MDR HIV-1. Doravirine activity appeared to be inferred with fair accuracy by the HIVdb algorithm.

The Potential of Moringa oleifera to Ameliorate HAART-Induced Pathophysiological Complications

Highly active antiretroviral therapy (HAART) comprises a combination of two or three antiretroviral (ARV) drugs that are administered together in a single tablet. These drugs target different steps within the human immunodeficiency virus (HIV) life cycle, providing either a synergistic or additive antiviral effect; this enhances the efficiency in which viral replication is suppressed. HIV cannot be completely eliminated, making HAART a lifetime treatment. With long-term HAART usage, an increasing number of patients experience a broadening array of complications, and this significantly affects their quality of life, despite cautious use. The mechanism through which ARV drugs induce toxicity is associated with metabolic complications such as mitochondrial dysfunction, oxidative stress, and inflammation. To address this, it is necessary to improve ARV drug formulation without compromising its efficacy; alternatively, safe supplementary medicine may be a suitable solution. The medicinal plant Moringa oleifera (MO) is considered one of the most important sources of novel nutritionally and pharmacologically active compounds that have been shown to prevent and treat various diseases. MO leaves are rich in polyphenols, vitamins, minerals, and tannins; studies have confirmed the therapeutic properties of MO. MO leaves provide powerful antioxidants, scavenge free radicals, promote carbohydrate metabolism, and repair DNA. MO also induces anti-inflammatory, hepatoprotective, anti-proliferative, and anti-mutagenic effects. Therefore, MO can be a source of affordable and safe supplement therapy for HAART-induced toxicity. This review highlights the potential of MO leaves to protect against HAART-induced toxicity in HIV patients.

Current medicinal chemistry strategies in the discovery of novel HIV-1 ribonuclease H inhibitors

During HIV-1 genome replication, the viral reverse transcriptase-associated ribonuclease H (RT-associated RNase H) activity hydrolyzes the RNA strand of RNA/DNA heteroduplex intermediates. As of today, HIV-1 RNase H inhibitors (RHIs) remain at an investigational level, although none of them reached clinical trials. Therefore, RNase H remains as an attractive target for drug design and development. In this paper, we review the current status of medicinal chemistry strategies aimed at the discovery of novel RHIs, while discussing problems encountered in their characterization and further development, thereby providing an update on recent progress in the field.

APOBEC3 selects V179I in HIV-1 reverse transcriptase to provide selective advantage for non-nucleoside reverse transcriptase inhibitor-resistant mutants

The V179I substitution in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is selected in humans or mouse models treated with certain nonnucleoside reverse transcriptase inhibitors (NNRTIs). While it is often observed together with other NNRTI resistance mutations, V179I does not confer drug resistance. To understand how V179I arises during NNRTI treatment, we characterized it in HIV-1 molecular clones with or without the NNRTI resistance mutations Y181C or Y181V. While V179I alone did not confer resistance to any NNRTIs tested, when present with Y181C/V it enhanced drug resistance to some NNRTIs by 3- to 8-fold. In replication competition experiments in the presence of the NNRTI rilpivirine (RPV), V179I modestly enhanced Y181C HIV-1 or Y181V HIV-1 replication compared to viruses without V179I. As V179I arises from a G to A mutation, we evaluated whether it could arise due to host APOBEC3 deaminase activity and be maintained in the presence of a NNRTI to provide a selective advantage for the virus. V179I was detected in some humanized mice treated with RPV and was associated with G to A mutations characteristic of APOBEC3 activity. In RPV selection experiments, the frequency of V179I in HIV-1 was accelerated in CD4+ T cells expressing higher APOBEC3F and APOBEC3G levels. Our results provide evidence that V179I in HIV-1 RT can arise due to APOBEC-mediated G to A hypermutation and can confer a selective advantage to drug-resistant HIV-1 isolates in the presence of some NNRTIs.

Epidemiology and Clinical Outcomes of HIV Infection in South-Central China: A Retrospective Study From 2003 to 2018

Objective

HIV epidemiology in South-Central China is rarely reported. This study aims to characterize epidemiological and clinical features of HIV-infected patients in Hunan Province, located in South-Central China, for better management of HIV infections.

Methods

This retrospective study retrieved multi-center records of laboratory-confirmed HIV-infected patients in Hunan province. Information on HIV-associated mortality and antiretroviral therapies was also collected.

Results

Among 34,297 patients diagnosed with HIV infections from 2003 to 2018, 73.9% were males, 41.3% were older adults (≥50 years), and 71.2% were infected by heterosexual transmission. Despite a slow growth of new HIV infections in the overall population, annual percentages of HIV infections increased in older males (85.3% through heterosexual transmission) and young patients <30 years (39.9% through homosexual transmission). At baseline, serum levels of CD4+ T-cell counts were lower in older adults (191.0 cells/μl) than in young patients (294.6 cells/μl, p-value < 0.0001). A large proportion (47.2%, N = 16,165) of HIV-infected patients had advanced HIV disease (CD4+ T-cell counts < 200 cells/μl) from 2003 to 2018. All-cause mortality (57.0% due to AIDS-related illnesses) was reported among 4411 HIV-infected patients, including 2619 older adults. The 10-year survival rate was significantly lower in elderly males than in other patients (59.0 vs. 78.4%, p-value < 0.05).

Conclusions

Elderly males are prone to HIV infections with a high risk of HIV-associated fatality. Our findings support early prevention and critical care for elderly populations to control HIV infections.

Doravirine and Islatravir Have Complementary Resistance Profiles and Create a Combination with a High Barrier to Resistance

Doravirine (DOR), a non-nucleoside reverse transcriptase inhibitor (NNRTI), was approved for treatment of HIV-1 infection in 2018. In the pivotal phase 3 trials, DRIVE-FORWARD and DRIVE-AHEAD, 7 out of 747 (0.9%) treatment-naive participants treated with DOR plus two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) met protocol-defined virologic failure criteria and showed phenotypic resistance to DOR at week 48. The most common DOR resistance-associated mutation (RAM) detected in 5 of the 7 resistant isolates was F227C. Six isolates bearing NRTI RAMs (M184V and/or K65R) were resistant to lamivudine (3TC) and emtricitabine (FTC) but not to other approved NRTIs. All DOR-resistant isolates were susceptible or hypersusceptible (fold change of <0.25) to islatravir (ISL), a nucleoside reverse transcriptase translocation inhibitor (NRTTI). Isolate hypersusceptibility to ISL required F227C, in contrast to zidovudine, an NRTI, which required M184V. Based on the frequent emergence of F227C, we hypothesized that DOR and ISL would create a combination (DOR/ISL) with a high barrier to resistance. In de novo resistance selection studies in MT4-GFP cells (MT4 cells engineered to express green fluorescent protein), DOR/ISL synergistically prevented viral breakthrough at a threshold of 2× the half-maximal inhibitory concentration (IC₅₀). DOR/ISL exhibited a higher barrier to resistance than DOR/3TC and dolutegravir (DTG)/3TC. Resistance analysis showed no emergence of substitutions at F227, an observation consistent with its ability to confer hypersusceptibility to ISL. Overall, the data demonstrate that DOR/ISL creates a 2-drug combination with a higher barrier to resistance, consistent with the reported clinical activity.

Approved HIV reverse transcriptase inhibitors in the past decade

HIV reverse transcriptase (RT) inhibitors are the important components of highly active antiretroviral therapies (HAARTs) for anti-HIV treatment and pre-exposure prophylaxis in clinical practice. Many RT inhibitors and their combination regimens have been approved in the past ten years, but a review on their drug discovery, pharmacology, and clinical efficacy is lacking. Here, we provide a comprehensive review of RT inhibitors (tenofovir alafenamide, rilpivirine, doravirine, dapivirine, azvudine and elsulfavirine) approved in the past decade, regarding their drug discovery, pharmacology, and clinical efficacy in randomized controlled trials. Novel RT inhibitors such as islatravir, MK-8504, MK-8507, MK8583, IQP-0528, and MIV-150 will be also highlighted. Future development may focus on the new generation of novel antiretroviral inhibitors with higher bioavailability, longer elimination half-life, more favorable side-effect profiles, fewer drug-drug interactions, and higher activities against circulating drug-resistant strains.

Contemporary Medicinal Chemistry Strategies for the Discovery and Development of Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors

Currently, HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a major component of the highly active anti-retroviral therapy (HAART) regimen. However, the occurrence of drug-resistant strains and adverse reactions after long-term usage have inevitably compromised the clinical application of NNRTIs. Therefore, the development of novel inhibitors with distinct anti-resistance profiles and better pharmacological properties is still an enormous challenge. Herein, we summarize state-of-the-art medicinal chemistry strategies for the discovery of potent NNRTIs, such as structure-based design strategies, contemporary computer-aided drug design, covalent-binding strategies, and the application of multi-target-directed ligands. The strategies described here will facilitate the identification of promising HIV-1 NNRTIs.

Liposomes as Carriers for the Delivery of Efavirenz in Combination with Glutathione—An Approach to Combat Opportunistic Infections

Human immunodeficiency virus (HIV)-infected individuals display an enhanced production of reactive oxygen species (ROS). This reduction of antioxidant capacity in host tissues has been related to the decrease in total levels of ROS scavengers such as glutathione (GSH). Prevention of opportunistic infections due to a weakened immune system is becoming a key strategy along with HIV elimination. Research in these directions is clearly warranted, especially a combination of antiretrovirals and antioxidants to ameliorate oxidative stress, improve intracellular uptake and target viral reservoirs. Hence, we aimed to formulate liposomes loaded with the antiretroviral drug efavirenz (EFA) in the presence of glutathione, as these carriers can be engineered to enhance the ability to reach the target reservoirs. The goal of the present work was to investigate the intracellular uptake of EFA-loaded liposome (with and without GSH) by human monocytic leukemia cells (THP-1 cells) and examine cell viability and ROS scavenging activity. Results obtained provided significant data as follows: (i) treatment with EFA and GSH combination could enhance the uptake and reduce cytotoxicity; (ii) encapsulation of EFA into liposomes increased its levels in the macrophages, which was further enhanced in the presence of GSH; (iii) delivery of EFA in the presence of GSH quenched the intracellular ROS, which was significantly higher when delivered via liposomes. Data revealed that a combination of EFA and GSH encompasses advantages; hence, GSH supplementation could be a safe and cost-effective treatment to slow the development of HIV infection and produce an immune-enhancing effect.

Doravirine: its role in HIV treatment

PURPOSE OF REVIEW

We reviewed evidence concerning the novel nonnucleoside reverse transcriptase inhibitor doravirine, aiming to identify situations where it may be selected in preference to integrase inhibitors.

RECENT FINDINGS

Doravirine is licenced for the treatment of HIV-1 in North America and Europe. In two multicentre randomized controlled trials, noninferiority with comparator drugs efavirenz and darunavir/ritonavir was observed at 96 weeks. Doravirine is associated with a lower incidence of neuropsychiatric side effects relative to efavirenz, and favourable lipid changes relative to darunavir over 96 weeks. A lower incidence of weight gain, relative to indirect comparisons with integrase inhibitors, was observed. Doravirine has a high genetic barrier to resistance with retained activity in the presence of single NNRTI mutations K103N, Y181C and G190A. Primary drug resistance is infrequent and may be higher in South Africa relative to European populations. Doravirine may be used in renal or hepatic impairment and has a low potential for drug-drug interactions.

SUMMARY

Doravirine is a well tolerated and effective agent in ART-naive patients. Direct comparison with integrase inhibitors, and evidence on the outcomes of treatment with doravirine in the presence of prior NNRTI experience are required to better elucidate which patients will benefit most from doravirine therapy.

Epidemiology and Transmitted HIV-1 Drug Resistance among Treatment-Naïve Individuals in Israel, 2010-2018

Despite the low prevalence of HIV-1 in Israel, continuous waves of immigration may have impacted the local epidemic. We characterized all people diagnosed with HIV-1 in Israel in 2010–2018. The demographics and clinical data of all individuals (n = 3639) newly diagnosed with HIV-1 were retrieved. Subtypes, transmitted drug-resistance mutations (TDRM), and phylogenetic relations, were determined in >50% of them. In 39.1%, HIV-1 transmission was through heterosexual contact; 34.3% were men who have sex with men (MSM); and 10.4% were people who inject drugs. Many (>65%) were immigrants. Israeli-born individuals were mostly (78.3%) MSM, whereas only 9% of those born in Sub-Saharan Africa (SSA), Eastern Europe and Central Asia (EEU/CA), were MSM. The proportion of individuals from SSA decreased through the years 2010–2018 (21.1% in 2010–2012; 16.8% in 2016–2018) whereas those from EEU/CA increased significantly (21% in 2010–2012; 27.8% in 2016–2018, p < 0.001). TDRM were identified in 12.1%; 3.7, 3.3 and 6.6% had protease inhibitors (PI), nucleotide reverse transcriptase inhibitors (NRTI), and non-nucleoside reverse transcriptase inhibitors (NNRTI) TDRM, respectively, with the overall proportion remaining stable in the studied years. None had integrase TDRM. Subtype B was present in 43.9%, subtype A in 25.2% (A6 in 22.8 and A1 in 2.4%) and subtype C in 17.1% of individuals. Most MSM had subtype B. Subtype C carriers formed small clusters (with one unexpected MSM cluster), A1 formed a cluster mainly of locally-born patients with NNRTI mutations, and A6 formed a looser cluster of individuals mainly from EEU. Israelis, <50 years old, carrying A1, had the highest risk for having TDRM. In conclusion, an increase in immigrants from EEU/CA and a decrease in those from SSA characterized the HIV-1 epidemic in 2010–2018. Baseline resistance testing should still be recommended to identify TDRM, and improve surveillance and care.

Update and latest advances in antiretroviral therapy

Since the first cases of AIDS appeared in 1981, human immunodeficiency virus type 1 (HIV-1) infection has reached pandemic proportions. Forty years later, research has led to the approval of more than 30 antiretroviral drugs, while combination therapies have turned HIV-1 infection into a chronic, but manageable disease. Still, drug toxicity and acquired and transmitted drug resistance remain as major threats to therapy success. In this review, we provide an overview on currently available anti-HIV drugs and the latest developments in antiretroviral therapy, focused on new antiretroviral agents acting on known and unexploited antiviral targets, prevention therapies aimed to improve available drug combinations, and research on new long-acting therapies, particularly those involving novel drug candidates such as lenacapavir or islatravir.

Continuum of Care UNAIDS Fast-Track Targets Evaluation of Patients Living with Human Immunodeficiency Virus Infection

The current study evaluated the progress of continuum healthcare for patients living with human immunodeficiency virus (HIV) infection from Cluj County in two moments, 2016 and 2020, and compared the results to the Fast-Track targets (FTTs) proposed by the Joint United Nations Programme (UNAIDS) on HIV/AIDS. By the end of 2020, 368 out of 385 confirmed HIV-positive patients from Cluj County were under surveillance in our center, representing almost 95% of the patients living with HIV and knowing their diagnosis, compared to 87.9% in 2016. Nearly 97% of those in active follow-up from Cluj County were under antiretroviral therapy (ART) in 2020, compared to 89% in 2016. The number of virally suppressed patients from those under ART was almost 94% in 2020, compared to 82.7% in 2016, and the increase is observed regardless of the ART regime. A shift towards integrase strand transfer inhibitors, with a higher efficacy, fewer adverse effects, and fewer drug interactions, is observed, which could contribute to the decrease in HIV transmission.

An Overview of Human Immunodeficiency Virus-1 Antiretroviral Drugs: General Principles and Current Status

Treatment with highly active antiretroviral therapy (HAART) can prolong a patient's life-span by disrupting pivotal steps in the replication cycle of the human immunodeficiency virus-1 (HIV-1). However, drug resistance is emerging as a major problem worldwide due to the prolonged period of treatment undergone by HIV-1 patients. Since the approval of zidovudine in 1987, over thirty antiretroviral drugs have been categorized into the following six distinct classes based on their biological function and resistance profiles: (1) nucleoside analog reverse-transcriptase inhibitors; (2) non–nucleoside reverse transcriptase inhibitors; (3) integrase strand transferase inhibitors; (4) protease inhibitors; (5) fusion inhibitors; and (6) co-receptor antagonists. Additionally, several antiretroviral drugs have been developed recently, such as a long active drug, humanized antibody and pro-drug metabolized into an active form in the patient's body. Although plenty of antiretroviral drugs are beneficially used to treat patients with HIV-1, the ongoing efforts to develop antiretroviral drugs have overcome the drug resistances, adverse effects, and limited adherence of drugs observed in previous drugs to some extent. Furthermore, studies focused on agents targeting latent HIV-1 reservoirs should be strengthened, as that may lead to eradication of HIV-1.

Cell culture selections reveal favourable drug resistance profiles for doravirine and islatravir

BACKGROUND

The newer generation NNRTIs, including doravirine and rilpivirine, were designed to show high potency and overcome K103N, Y181C and G190A resistance.

OBJECTIVES

To assess emergent resistance to doravirine and rilpivirine, alone and paired with lamivudine or islatravir through in vitro drug selections.

METHODS

Subtype B (n = 3), non-B subtype (n = 3), and pNL4.3 viral isolates were passaged in cord blood mononuclear cells with progressively increasing concentrations of drug(s). Genotypic analysis compared the acquisition and accumulation of drug resistance mutations at weeks 8 and 24 following drug pressure. Cell-based phenotypic assays assessed cross-resistance patterns to NNRTIs by acquired resistance mutations.

RESULTS

Doravirine pressure resulted in the acquisition of V108I (6/7) and V106A/I/M (5/7) mutations at weeks 8, followed by F227L (4/7), Y318F (4/7), M230L (2/7) or L234I (2/7) by weeks 24. In contrast, rilpivirine resulted in E138K (5/7) followed by L100I (3/7), K101E (1/7), or M230L (1/7). Doravirine resistance pathways retained susceptibility to rilpivirine, whereas rilpivirine resistance conferred intermediate resistance (12-152-fold) to doravirine. Dual selections with islatravir or lamivudine delayed and diminished emergent resistance to doravirine, resulting in V108I (9/15) with fewer or no other changes at weeks 24. There was a lesser delay in emergent resistance to rilpivirine when combined with islatravir or lamivudine. The M184V mutation did not arise in dual selections with islatravir or lamivudine.

CONCLUSIONS

Doravirine showed a more robust resistance profile compared with other NNRTIs. The long intracellular half-life of islatravir and delayed acquisition of resistance in dual selections provide an opportunity for long-acting treatment options.

Biochemical profiling of anti-HIV prodrug Elsulfavirine (Elpida®) and its active form VM1500A against a panel of twelve human carbonic anhydrase isoforms

The non-nucleoside reverse transcriptase inhibitor VM1500A is approved for the treatment of HIV/AIDS in its N-acyl sulphonamide prodrug form elsulfavirine (Elpida^®). Biochemical profiling against twelve human carbonic anhydrase (CA, EC 4.2.1.1) isoforms showed that while elsulfavirine was a weak inhibitor of all isoforms, VM1500A potently and selectively inhibited human (h) hCA VII isoform, a proven target for the therapy of neuropathic pain. The latter is a common neurologic complication of HIV infection and we hypothesise that by using Elpida^® in patients may help alleviate this debilitating symptom.

An Update on Antiretroviral Therapy

Human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS) still claim many lives across the world. However, research efforts during the last 40 years have led to the approval of over 30 antiretroviral drugs and the introduction of combination therapies that have turned HIV infection into a chronic but manageable disease. In this chapter, we provide an update on current available drugs and treatments, as well as future prospects towards reducing pill burden and developing long-acting drugs and novel antiretroviral therapies. In addition, we summarize efforts to cure HIV, including pharmaceutical strategies focused on the elimination of the virus.

Comparative safety review of recommended, first-line single-tablet regimens in patients with HIV

Introduction Different single-tablet regimens (STRs), containing one or two nucleoside reverse transcriptase inhibitors (NRTIs) plus an anchor drug, are available for the use in naïve, HIV-infected patients. Despite some restrictions in the use of particular regimens in certain situations (e.g., HBV coinfection), International guidelines do not provide indications to prefer any regimen over others concerning the tolerability profile. We aimed to assess advantages and disadvantages of the most prescribed STRs.Areas covered An extensive review of articles published in English language was conducted on PubMed, looking for evidence about STRs in naïve, HIV-infected population. Safety outcomes of registrational trials were assessed, giving priority to studies directly comparing STRs included in our research (abacavir/lamivudine/dolutegravir, tenofovir alafenamide/emtricitabine/bictegravir, lamivudine/dolutegravir, tenofovir alafenamide/emtricitabine/darunavir/cobicistat, tenovofir disoproxil fumarate/lamivudine/doravirine). Data from cohort studies and meta-analyses were also assessed, extrapolating the main evidence about the combinations of interest.Expert opinion Integrase inhibitors (InsTIs)-based regimens have few interruptions for adverse events and few drug-related adverse events, with tenofovir alafenamide/emtricitabine/dolutegravir and lamivudine/dolutegravir being the most tolerable ones. However, neuropsychiatric adverse events and metabolic issues could prompt the alternative use of darunavir or doravirine-based combinations, even if a superior safety profile of these combinations over InSTIs has yet to be demonstrated.

Genetic Diversity of SARS-CoV-2 over a One-Year Period of the COVID-19 Pandemic: A Global Perspective

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic of coronavirus disease in 2019 (COVID-19). Genome surveillance is a key method to track the spread of SARS-CoV-2 variants. Genetic diversity and evolution of SARS-CoV-2 were analyzed based on 260,673 whole-genome sequences, which were sampled from 62 countries between 24 December 2019 and 12 January 2021. We found that amino acid (AA) substitutions were observed in all SARS-CoV-2 proteins, and the top six proteins with the highest substitution rates were ORF10, nucleocapsid, ORF3a, spike glycoprotein, RNA-dependent RNA polymerase, and ORF8. Among 25,629 amino acid substitutions at 8484 polymorphic sites across the coding region of the SARS-CoV-2 genome, the D614G (93.88%) variant in spike and the P323L (93.74%) variant in RNA-dependent RNA polymerase were the dominant variants on six continents. As of January 2021, the genomic sequences of SARS-CoV-2 could be divided into at least 12 different clades. Distributions of SARS-CoV-2 clades were featured with temporal and geographical dynamics on six continents. Overall, this large-scale analysis provides a detailed mapping of SARS-CoV-2 variants in different geographic areas at different time points, highlighting the importance of evaluating highly prevalent variants in the development of SARS-CoV-2 antiviral drugs and vaccines.

Life-long passion for antiviral research and drug development: 80th birthday of Prof. Dr. Erik De Clercq

Since the 1950s, great efforts have been made to develop antiviral agents against many infectious diseases such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), human cytomegalovirus (HCMV), herpes simplex virus (HSV), and varicella-zoster virus (VZV). Among the list of nearly 106 antiviral agents approved in the past five decades, Prof. Erik De Clercq has contributed to the development of 7 antiviral drugs: tenofovir disoproxil fumarate (Viread®) for HIV and HBV treatment, tenofovir alafenamide (Vemlidy®) for HIV and HBV treatment, brivudine (Zostex®) for HSV-1 and VZV treatment, valacyclovir (Valtrex®) for HSV and VZV treatment, adefovir dipivoxil (Hepsera®) for HBV treatment, stavudine (Zerit®) for HIV treatment, and cidofovir (Vistide®) for treating HCMV retinitis in AIDS patients. In addition to the above antiviral drugs, his contributions include two anti-cancer drugs: rabacfosadine (Tanovea®-CA1) for canine lymphoma and plerixafor (Mozobil®) for multiple myeloma and non-Hodgkin's lymphoma. These achievements are driven by his life-long passions for antiviral research and successful collaborations worldwide. To honor the 80th birthday of Prof. Erik De Clercq, this study highlights his scientific achievements and the importance of life-long passions and collaborations in the success of antiviral research and drug development.

Covalent Inhibition of Wild-Type HIV-1 Reverse Transcriptase Using a Fluorosulfate Warhead

Covalent inhibitors of wild-type HIV-1 reverse transcriptase (CRTIs) are reported. Three compounds derived from catechol diether non-nucleoside inhibitors (NNRTIs) with addition of a fluorosulfate warhead are demonstrated to covalently modify Tyr181 of HIV-RT. X-ray crystal structures for complexes of the CRTIs with the enzyme are provided, which fully demonstrate the covalent attachment, and confirmation is provided by appropriate mass shifts in ESI-TOF mass spectra. The three CRTIs and six noncovalent analogues are found to be potent inhibitors with both IC₅₀ values for in vitro inhibition of WT RT and EC₅₀ values for cytopathic protection of HIV-1-infected human T-cells in the 5-320 nM range.

Drug Discovery of Nucleos(t)ide Antiviral Agents: Dedicated to Prof. Dr. Erik De Clercq on Occasion of His 80th Birthday

Nucleoside and nucleotide analogues are essential antivirals in the treatment of infectious diseases such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), herpes simplex virus (HSV), varicella-zoster virus (VZV), and human cytomegalovirus (HCMV). To celebrate the 80th birthday of Prof. Dr. Erik De Clercq on 28 March 2021, this review provides an overview of his contributions to eight approved nucleos(t)ide drugs: (i) three adenosine nucleotide analogues, namely tenofovir disoproxil fumarate (Viread^®) and tenofovir alafenamide (Vemlidy^®) against HIV and HBV infections and adefovir dipivoxil (Hepsera^®) against HBV infections; (ii) two thymidine nucleoside analogues, namely brivudine (Zostex^®) against HSV-1 and VZV infections and stavudine (Zerit^®) against HIV infections; (iii) two guanosine analogues, namely valacyclovir (Valtrex^®, Zelitrex^®) against HSV and VZV and rabacfosadine (Tanovea^®-CA1) for the treatment of lymphoma in dogs; and (iv) one cytidine nucleotide analogue, namely cidofovir (Vistide^®) for the treatment of HCMV retinitis in AIDS patients. Although adefovir dipivoxil, stavudine, and cidofovir are virtually discontinued for clinical use, tenofovir disoproxil fumarate and tenofovir alafenamide remain the most important antivirals against HIV and HBV infections worldwide. Overall, the broad-spectrum antiviral potential of nucleos(t)ide analogues supports their development to treat or prevent current and emerging infectious diseases worldwide.

Integrase Strand Transfer Inhibitors Are Effective Anti-HIV Drugs

Integrase strand transfer inhibitors (INSTIs) are currently recommended for the first line treatment of human immunodeficiency virus type one (HIV-1) infection. The first-generation INSTIs are effective but can select for resistant viruses. Recent advances have led to several potent second-generation INSTIs that are effective against both wild-type (WT) HIV-1 integrase and many of the first-generation INSTI-resistant mutants. The emergence of resistance to these new second-generation INSTIs has been minimal, which has resulted in alternative treatment strategies for HIV-1 patients. Moreover, because of their high antiviral potencies and, in some cases, their bioavailability profiles, INSTIs will probably have prominent roles in pre-exposure prophylaxis (PrEP). Herein, we review the current state of the clinically relevant INSTIs and discuss the future outlook for this class of antiretrovirals.

Avoiding Drug Resistance in HIV Reverse Transcriptase

HIV reverse transcriptase (RT) is an enzyme that plays a major role in the replication cycle of HIV and has been a key target of anti-HIV drug development efforts. Because of the high genetic diversity of the virus, mutations in RT can impart resistance to various RT inhibitors. As the prevalence of drug resistance mutations is on the rise, it is necessary to design strategies that will lead to drugs less susceptible to resistance. Here we provide an in-depth review of HIV reverse transcriptase, current RT inhibitors, novel RT inhibitors, and mechanisms of drug resistance. We also present novel strategies that can be useful to overcome RT's ability to escape therapies through drug resistance. While resistance may not be completely avoidable, designing drugs based on the strategies and principles discussed in this review could decrease the prevalence of drug resistance.

Emerging Trends in the Long-Acting Antiretroviral Therapy: Current Status and Therapeutic Challenges

Antiretroviral drug therapy has significantly improved the prognosis and life expectancy of people living with HIV over the years. But this progress comes with an important caveat that antiretroviral regimens generally require adherence to life-long, daily dosing, to keep viral multiplication under check. Non-adherence to such dosing leads to decreased efficacy and increased drug resistance against antiretroviral drugs. Besides, poor drug penetration to certain tissues like CNS and lymph nodes leads to the build-up of viral reservoirs in these sites. To combat some of these challenges and improve patient compliance, long-acting antiretroviral drugs, are a new weapon in the arsenal, in the fight against HIV. Few long-acting preparations have been approved, and several others are in various clinical and preclinical stages of development. However, long-acting formulations also have their share of clinical issues like limited drug distribution, long term adverse drug reactions, drug-drug interactions, and gradual development of drug resistance. Modern technological premises are being tested to mitigate some of these problems. One such promising approach involves nanotechnological methods, which are being used to develop ultra-long acting formulations and drug delivery systems, targeting tissues with residual HIV concentration. Long-Acting Slow Effective Release Antiretroviral Therapy aka LASER ART, also builds on nanotechnology and prodrug modifications to design preparations with tailor-made favorable pharmacokinetics and wider drug distribution. These recent advances are fueling the progression of antiretroviral therapy towards eliminating the disease.

Druggability modification strategies of the diarylpyrimidine-type non-nucleoside reverse transcriptase inhibitors

Drug discovery of human immunodeficiency virus (HIV) is a hot field in medicinal chemistry community for many years. The diarylpyrimidines (DAPYs) are the second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) targeting reverse transcriptase, playing a great irreplaceable role in HIV transcriptional therapy. However, fast-growing drug-resistant mutations as nonnegligible challenge are still unpredictably appeared in the clinical practice, leading to deactivate or reduce the existing drugs. In the last 20 years, more and more novel DAPY derivatives have developed with the purpose to counter the mutants. Nevertheless, most of them have dissatisfactory pharmacokinetics (PK) or poor antiviral activity toward resistant mutant strains. In this article, we will analyze the NNRTI derivatives with promising druggability, and summarize a series of druggability modification strategies to improve the antiviral activity, reduce toxicity and improve the PK properties in recent years. The prospects of DAPYs and the directions for future efforts will be discussed.

Design, synthesis, and evaluation of "dual-site"-binding diarylpyrimidines targeting both NNIBP and the NNRTI adjacent site of the HIV-1 reverse transcriptase

Inspired by our previous efforts to improve the drug-resistance profiles of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs), a novel series of "dual-site" binding diarylpyrimidine (DAPY) derivatives targeting both the NNRTI adjacent site and NNRTIs binding pocket (NNIBP) were designed, synthesized, and evaluated for their anti-HIV potency in TZM-bl and MT-4 cells. Eight compounds exhibited moderate to excellent potencies in inhibiting wild-type (WT) HIV-1 replication with EC₅₀ values ranging from 2.45 nM to 5.36 nM, and 14c (EC₅₀ = 2.45 nM) proved to be the most promising inhibitor. Of note, 14c exhibited potent activity against the single mutant strain E138K (EC₅₀ = 10.6 nM), being comparable with ETR (EC₅₀ = 9.80 nM) and 3.5-fold more potent than that of compound 7 (EC₅₀ = 37.3 nM). Moreover, 14c acted as a classical NNRTI with high affinity for WT HIV-1 RT (IC₅₀ = 0.0589 μM). The detailed structure-activity relationships (SARs) of the representative compounds were also determined, and further supported by molecular dynamics simulation. Overall, we envision that the "dual-site"-binding NNRTIs have significant prospects and pave the way for the next round of rational design of potent anti-HIV-1 agents.

Advances in understanding the initiation of HIV-1 reverse transcription

Many viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Human Immunodeficiency Virus (HIV), use RNA as their genetic material. How viruses harness RNA structure and RNA-protein interactions to control their replication remains obscure. Recent advances in the characterization of HIV-1 reverse transcriptase, the enzyme that converts its single-stranded RNA genome into a double-stranded DNA copy, reveal how the reverse transcription complex evolves during initiation. Here we highlight these advances in HIV-1 structural biology and discuss how they are furthering our understanding of HIV and related ribonucleoprotein complexes implicated in viral disease.