Class Of Non-nucleoside Reverse Transcriptase Inhibitors Research Articles

Dynamics of Rilpivirine Resistance-Associated Mutation: E138 in Reverse Transcriptase among Antiretroviral-Naive HIV-1-Infected Individuals in Turkey.

Rilpivirine, one of the non-nucleoside reverse transcriptase inhibitors class anti-HIV agents, is used as an alternative drug to treat HIV-1-positive individuals according to current antiretroviral therapy (ART) guidelines. Mutation in the position E138 in HIV-1 reverse transcriptase (RT) leads to resistance to rilpivirine, alone reducing its susceptibility two to threefolds. The main aim of this study was to determine the dynamics of E138 mutation in the RT domain of the HIV-1 pol gene; in 6398 newly diagnosed and treatment-naive individuals in Turkey from 2013 to 2021. Rilpivirine-associated mutations were found among 424 (6.6%) out of 6398. Individuals with the E138 mutation had significantly higher HIV-1 RNA load than individuals without the E138 mutation (p = .044). The E138 mutation was mainly observed in the B subtype (40%) of HIV-1 compared to the non-B subtypes (26.9%) and the circulating recombinant forms (33.1%) (p < .001). Most E138 mutations were E138A (80%), followed by E138G (16.5%). This study uncovered the dynamics of rilpivirine-associated mutations over a long period and a large patient population. Before administering ART regimens consisting of rilpivirine, resistance monitoring is highly recommended for effective patient management in the treatment-of naive HIV-1-infected individuals.

Divergent effects of HIV reverse transcriptase inhibitors on pancreatic beta-cell function and survival: Potential role of oxidative stress and mitochondrial dysfunction

Antiretroviral therapy (ART), a life-saving treatment strategy in HIV/AIDS, has been implicated in increasing the risk of type 2 diabetes mellitus (T2DM). Direct damaging effects on beta-cell function and survival by either non-nucleoside reverse transcriptase inhibitors (NNRTIs) or nucleoside/tide reverse transcriptase inhibitors (NRTIs) may predispose individuals to developing T2DM or if already type 2 diabetic, to insulin dependency. The aim of this study was to investigate the effects of the NNRTIs efavirenz, rilpivirine and doravirine, and the NRTIs tenofovir disoproxil fumarate and emtricitabine, on beta-cell function and survival while suggesting potential cellular and molecular mechanism(s). Our results show contrasting effects within the NNRTI class as doravirine did not cause damaging effects in the rat insulinoma INS-1E cells while efavirenz and rilpivirine reduced insulin release and cell viability, and induced apoptosis in INS-1E cells. Additionally, efavirenz and rilpivirine increased ROS generation, disrupted Δψm and upregulated the mRNA and protein expression of CHOP and GRP78, key markers of endoplasmic reticulum stress. In silico docking studies predict a possible inhibition of the mitochondrial ATP synthase by rilpivirine. On the contrary, both the NRTIs tenofovir disoproxil fumarate and emtricitabine did not affect GSIS, cell viability and apoptosis/necrosis levels in INS-1E cells. The deleterious effects observed in beta-cells exposed to efavirenz or rilpivirine may be, at least partially, mediated by oxidative stress and mitochondrial toxicity. These findings provide potential mechanism(s) by which efavirenz and rilpivirine may contribute to the pathogenesis of T2DM and the progression of T2DM to insulin dependency in HIV-infected type 2 diabetics.

Effect of non-nucleoside reverse transcriptase inhibitors and protease inhibitors on serum levels of myeloperoxidase and C-reactive protein in HIV-infected individuals

It remains unclear whether increased inflammatory and cardiovascular risk biomarkers differ depending on the class of antiretroviral that is used. This study evaluated the plasma levels of inflammatory and cardiovascular risk biomarkers, such as MPO, hs-CRP, glucose, lipid profile, ALT (GPT), AST (GOT), urea and creatinine, as well as the blood count, of all the 164 participants in the study, either infected or un-infected with HIV. Thirty of the 104 HIV-infected individuals did not receive any antiretroviral; twenty-four of them were treated with non-nucleoside reverse transcriptase inhibitor class; and fifty took protease inhibitors. The control group consisted of sixty non-HIV infected individuals. In the case of the HIV-infected volunteers, the CD4+ T lymphocyte counts and viral load were also analyzed. Regardless of the hematological and biochemical changes resulting from the antiretroviral therapy (ART), the MPO and hs-CRP values significantly increased for the HIV-infected individuals (treated or untreated), irrespective of the class of ART that was used. This is important because these biomarkers are designed to be predictors of the risk of cardiovascular disease. The results of this study provide supporting evidence for the hypothesis that HIV-infected individuals are at increased risk of developing cardiovascular disease related to chronic inflammations, despite virological control with ART, and regardless of the class of ART that is used.

An Alternative HIV-1 Non-Nucleoside Reverse Transcriptase Inhibition Mechanism: Targeting the p51 Subunit.

The ongoing development of drug resistance in HIV continues to push for the need of alternative drug targets in inhibiting HIV. One such target is the Reverse transcriptase (RT) enzyme which is unique and critical in the viral life cycle—a rational target that is likely to have less off-target effects in humans. Serendipitously, we found two chemical scaffolds from the National Cancer Institute (NCI) Diversity Set V that inhibited HIV-1 RT catalytic activity. Computational structural analyses and subsequent experimental testing demonstrated that one of the two chemical scaffolds binds to a novel location in the HIV-1 RT p51 subunit, interacting with residue Y183, which has no known association with previously reported drug resistance. This finding supports the possibility of a novel druggable site on p51 for a new class of non-nucleoside RT inhibitors that may inhibit HIV-1 RT allosterically. Although inhibitory activity was shown experimentally to only be in the micromolar range, the scaffolds serve as a proof-of-concept of targeting the HIV RT p51 subunit, with the possibility of medical chemistry methods being applied to improve inhibitory activity towards more effective drugs.

ACQUIRED ANTIRETROVIRAL DRUG RESISTANCE MUTATIONS UPON TREATMENT FAILURE IN HIV-1 INFECTED PEDIATRIC PATIENTS IN CENTRAL BRAZIL

Antiretroviral drug-resistance mutations compromise the successful treatment of children and adolescents infected with human immunodeficiency virus type 1 (HIV-1). We describe the clinical, virological, and immunological follow-up of a cohort of children and adolescents perinatally infected with HIV-1 treated at Hospital Estadual de Doenças Tropicais Dr. Anuar Auad – HDT, in Central Brazil, after therapeutic failure related to drug resistance mutations.We analyzed the results of the genotypic test (protease codons 1–99 and reverse transcriptase codons 1–325) performed from 2003 to 2015. The ARV susceptibility profile was analyzed according to Stanford HIV drug resistance database. A total of 65 patients (median age of 10 years; range, 18 m–18 y) with therapeutic failure (after a median of 55 months of follow up; range, 9 m–13 y) and plasma levels of HIV-1 RNA greater than 1,000 copies/mL which were included and demonstrated mutations in: nucleoside reverse transcriptase inhibitors (NRTIs), 98.5%; non nucleoside reverse transcriptase inhibitors (NNRTIs), 75.4%; and protease inhibitors (PI), 44.6%. The most frequent NRTI mutations were found in codon T215 (83.1%) with a predominance of T215Y (56.9%), followed by M184V (69.3%). In the NNRTI class, mutations K103N (36.9%) and 190A (23.1%) were predominant, and, in the protease, mutations 54VL (35.4%) and 82ASTL (32.3%) were found in approximately the same proportion, with a predominance of the M54V mutation. These results demonstrate the high levels of resistance to different classes of antiretrovirals in HIV-infected children and adolescents and the importance of genotypic resistance tests in this population.KEY WORDS: HIV; drug resistance; genotypes; child; adolescent.

Rational Design of Doravirine: From Bench to Patients.

Since the approval of nevirapine, the first HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI) in 1996, NNRTIs have helped play a critical role in maintaining viral suppression in people living with HIV. The many positive attributes of the class, including potency and long plasma half-life, make them attractive drug discovery targets. Given the availability of multiple once-daily integrase-based treatments for HIV-1 infection, the challenge to develop a new antiretroviral agent that addresses the needs of today's patients is formidable. However, with the increased availability of antiretrovirals for treatment and new pre-exposure prophylaxis guidelines, which should globally expand the use of antiretrovirals in prevention, it will be increasingly important to have access to multiple regimens with options from different classes that are well tolerated and convenient to ensure a sustained impact on the global epidemic. Many attempts to improve upon the NNRTI class have failed to deliver a desirable clinical profile consistent with the current landscape of treatment options. Doravirine is the only NNRTI to successfully advance through phase 3 clinical development and approval in recent years. Learning from the liabilities of approved NNRTIs, as well as past development failures, facilitated a rational approach to the discovery of doravirine by focusing on addressing the known safety/tolerability issues of commonly prescribed NNRTIs, such as central nervous system toxicity with efavirenz and potential cardiotoxicity due to off-target effects on cardiac ion channels with rilpivirine, using structural biology and characterization of resistance in vitro to address resistance liabilities and concentrating on the metabolic profile to limit the potential for drug-drug interactions. These preclinical efforts were critical to the design and selection of doravirine as a novel NNRTI that possessed the desired next-generation profile with the ultimate proof that these attributes translate to patients derived from clinical trials.

Doravirine: A Return of the NNRTI Class?

Objective: To compare and contrast doravirine (DOR) with other agents in the nonnucleoside reverse transcriptase inhibitor (NNRTI) class, review safety and efficacy data from both completed and ongoing clinical trials, and outline the potential place in therapy of DOR. Data Sources: A literature search using the PubMed database (inception to June 2019) was conducted using the search terms HIV, doravirine, non-nucleoside reverse transcriptase inhibitor, NNRTI, and MK-1439. Study Selection and Data Extraction: Clinical data were limited to those published in the English language from phase 2 or 3 clinical trials. Ongoing trials were identified through ClinicalTrials.gov. Data Synthesis: DOR was approved by the US Food and Drug Administration on the strength of 2 phase 3 randomized, double-blind, noninferiority clinical trials with additional studies currently underway examining its utility in other clinical scenarios. Relevance to Patient Care and Clinical Practice: The role of NNRTIs as part of antiretroviral (ARV) therapy has diminished in recent years given the introduction of more tolerable individual ARV agents and regimens. Despite this, new agents are still needed in the therapeutic arena because treatment failure as well as intolerance can still occur with many first-line therapies. The optimal place in therapy of DOR remains to be defined. Conclusions: DOR is a new NNRTI that represents a potential treatment option for treatment-naïve patients, without many of the previously described untoward effects of the NNRTI class.

Challenges and approaches in the discovery of human immunodeficiency virus type-1 non-nucleoside reverse transcriptase inhibitors.

The type I human immunodeficiency virus (HIV-1) pandemic affecting over 37 million people worldwide continues, with 1.8 million people newly infected each year. Highly active antiretroviral therapy is efficient at reducing viral load and nearly one-half of the infected population is on treatment. One of the most successful approaches for the treatment of HIV infections is the use of inhibitors for human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT). At present, there are six nonnucleoside reverse transcriptase inhibitors (NNRTIs) approved for clinical use: nevirapine (NVP), delavirdine (DLV), efavirenz (EFV), etravirine (ETV), rilpivirine (RPV), and elsulfavirine. In this review, we will cover the development of different classes of NNRTIs over the last two decades. We will give an overview of traditional medicinal chemistry strategies for structural modification as bioisosterism principles, scaffold hopping, substitute decoration, and molecular hybridization. Furthermore, computer-aid design as virtual screening, de novo design and free-energy perturbation will be described in details.

Resistance profile of children and adolescents infected with HIV-1 in urban areas in Togo.

Children and adolescents are more vulnerable than adults to virologic failure and the emergence of resistance. The objective of our study was to determine the resistance patterns in adolescents on antiretroviral therapy at Sylvanus Olympio University Hospital in Lome, Togo. From June 1 to September 30, 2014, we included patients who had been on HAART for more than 12 months in the pediatric ward of Sylvanus Olympio University Hospital. Patients with an HIV viral load ≥1000copies underwent resistance genotyping. Virologic failure was found in 36 of the 198 children and adolescents in the study (18.2%). Half were in WHO stage 3,72.2% were treated with a combination of two NRTIs (nucleoside reverse transcriptase inhibitors) and one NNRTI (non-nucleoside reverse transcriptase inhibitor). The mutations were mostly found in the NNRTI class with 100% mutations for EFV and NVP. The mutations associated with the most frequent NRTIs were M184V, Y181C, and T215Y. Our study shows the need to use PIs (boosted protease inhibitors) in most children treated with NNRTI. It is necessary to strengthen the virological monitoring of children on HAART.

Structural optimization of N1-aryl-benzimidazoles for the discovery of new non-nucleoside reverse transcriptase inhibitors active against wild-type and mutant HIV-1 strains

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are recommended components of preferred combination antiretroviral therapies used for the treatment of human immunodeficiency virus (HIV) infection. These regimens are extremely effective in suppressing virus replication. Recently, our research group identified some N1-aryl-2-arylthioacetamido-benzimidazoles as a novel class of NNRTIs. In this research work we report the design, the synthesis and the structure–activity relationship studies of new compounds (20–34) in which some structural modifications have been introduced in order to investigate their effects on reverse transcriptase (RT) inhibition and to better define the features needed to increase the antiviral activity. Most of the new compounds proved to be highly effective in inhibiting both RT enzyme at nanomolar concentrations and HIV-1 replication in MT4 cells with minimal cytotoxicity. Among them, the most promising N1-aryl-2-arylthioacetamido-benzimidazoles and N1-aryl-2-aryloxyacetamido-benzimidazoles were also tested toward a panel of single- and double-mutants strain responsible for resistance to NNRTIs, showing in vitro antiviral activity toward single mutants L100I, K103N, Y181C, Y188L and E138K. The best results were observed for derivatives 29 and 33 active also against the double mutants F227L and V106A. Computational approaches were applied in order to rationalize the potency of the new synthesized inhibitors.

HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors: SAR and Lead Optimization Using CoMFA and CoMSIA Studies (1995-2016).

Design of inhibitors for HIV-1 reverse transcriptase inhibition (HIV-1 RT) is one of the successful chemotherapies for the treatment of HIV infection. Among the inhibitors available for HIV-1 RT, non-nucleoside reverse transcriptase inhibitors (NNRTIs) have shown to be very promising and clinically approved drugs. However, the efficiency of many of these drugs has been reduced by the drug-resistant variants of HIV-1 RT. The aim of the current review is to provide a summary of lead optimization strategies from the 3D-QSARs studies on NNRTI class from the past 21 years (1995 to 2016). The conformation dependent-alignment based (CoMFA and CoMSIA) methods have been proven very successful ligand based strategy in the drug design. Here, CoMFA and CoMSIA studies reported for structurally distinct NNRTIs including thiazolobenzimidazole, dipyridodiazepinone, 1,1,3-trioxo [1,2,4]-thiadiazine, formimidoester disulfides, thiocarbamate, thiazolidinone derivatives, etc. have been discussed in detail. In addition, we explore the position of the functional groups that drive the protein-ligand interaction. The structure-activity relationship (SAR) revealed from CoMFA and CoMSIA studies of these drug classes is not only in agreement with the structure-based method but also provides an efficient way of lead optimization. In addition to molecular docking experiments, protein-ligand interaction fingerprints were calculated in order to understand the common binding mode of NNRTI compounds. Overall, this review enlightens the protein-ligand interactions with a detailed SAR discussion for chemotypes. Such discussion will help medicinal chemist to gain a better understanding for the design of novel and promising NNRTI candidates.

Viral Suppression and HIV Drug Resistance at 6 Months Among Women in Malawi's Option B+ Program: Results From the PURE Malawi Study.

In 2011, Malawi launched Option B+, a program of universal antiretroviral therapy (ART) treatment for pregnant and lactating women to optimize maternal health and prevent pediatric HIV infection. For optimal outcomes, women need to achieve HIVRNA suppression. We report 6-month HIVRNA suppression and HIV drug resistance in the PURE study. PURE study was a cluster-randomized controlled trial evaluating 3 strategies for promoting uptake and retention; arm 1: Standard of Care, arm 2: Facility Peer Support, and arm 3: Community Peer support. Pregnant and breastfeeding mothers were enrolled and followed according to Malawi ART guidelines. Dried blood spots for HIVRNA testing were collected at 6 months. Samples with ART failure (HIVRNA ≥1000 copies/ml) had resistance testing. We calculated odds ratios for ART failure using generalized estimating equations with a logit link and binomial distribution. We enrolled 1269 women across 21 sites in Southern and Central Malawi. Most enrolled while pregnant (86%) and were WHO stage 1 (95%). At 6 months, 950/1269 (75%) were retained; 833/950 (88%) had HIVRNA testing conducted, and 699/833 (84%) were suppressed. Among those with HIVRNA ≥1000 copies/ml with successful amplification (N = 55, 41% of all viral loads > 1000 copies/ml), confirmed HIV resistance was found in 35% (19/55), primarily to the nonnucleoside reverse transcriptase inhibitor class of drugs. ART failure was associated with treatment default but not study arm, age, WHO stage, or breastfeeding status. Virologic suppression at 6 months was <90% target, but the observed confirmed resistance rates suggest that adherence support should be the primary approach for early failure in option B+.

Design of New Uracil Derivatives Possessing Inhibitory Activity with Respect to Reverse Transcriptase of HIV-1 Mutant K103N/Y181C

New highly active N 1-substituted uracil derivatives of the HIV-1 nonnucleoside reverse transcriptase inhibitor class were designed. The structure—activity relationship provided a basis for building a computer model of the inhibitory activity against reverse transcriptase of HIV-1 mutant K103N/Y181C. New compounds that were more active than nevirapine were synthesized.

Prevalence of drug resistance mutations in HAART patients infected with HIV-1 CRF06_cpx in Estonia.

HIV-1 drug resistance mutations (DRMs) and substitutions were assessed after the failure of the first line non-nucleoside reverse transcriptase inhibitors (NNRTIs) + 2 nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) treatment regimens (efavirenz [EFV] + lamivudine[3TC] + zidovudine [ZDV] vs. EFV + 3TC + ddI) among the HIV-1 CRF06_cpx infected subjects in Estonia. HIV-1 genomic RNA was sequenced; DRMs and amino acid substitutions were compared in 44 treatment naïve and 45 first-line NNRTI + 2 NRTI treatment failed patients consisting of EFV + 3TC + ZDV (n = 17) and EFV + 3TC + didanosine[ddI] (n = 21) therapy failed sub-populations. At least one DRM was found in 78% of treatment experienced patients. The most common NRTI mutations were M184V (80%), L74V (31%), L74I (17%), K219E (9%), and M184I (9%), NNRTI mutations were K103N (83%), P225H (14%), L100I (11%), and Y188L (11%), reflecting generally the similar pattern of DRMs to that seen in treatment failed subtype B viruses. Sub-population analysis revealed that EFV + 3TC + ddI failed patients had more DRMs compared to EFV + 3TC + ZDV failed patients, especially the ddI DRM L74IV and several additional NNRTI DRMs. Additionally, CRF06_cpx specific mutation E179V and substitutions R32K, K122E, and V200AE were also detected in treatment experienced population. After the failure of the first-line EFV + 3TC + ddI therapy HIV-1 CRF06_cpx viruses develop additional NRTI and NNRTI mutations compared to EFV + 3TC + ZDV regimen. Therefore the usage of EFV + 3TC + ddI in this subtype decreases the options for next regimens containing abacavir, and NNRTI class agents.

The emerging profile of cross-resistance among the nonnucleoside HIV-1 reverse transcriptase inhibitors.

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are widely used to treat HIV-1-infected individuals; indeed most first-line antiretroviral therapies typically include one NNRTI in combination with two nucleoside analogs. In 2008, the next-generation NNRTI etravirine was approved for the treatment of HIV-infected antiretroviral therapy-experienced individuals, including those with prior NNRTI exposure. NNRTIs are also increasingly being included in strategies to prevent HIV-1 infection. For example: (1) nevirapine is used to prevent mother-to-child transmission; (2) the ASPIRE (MTN 020) study will test whether a vaginal ring containing dapivirine can prevent HIV-1 infection in women; (3) a microbicide gel formulation containing the urea-PETT derivative MIV-150 is in a phase I study to evaluate safety, pharmacokinetics, pharmacodynamics and acceptability; and (4) a long acting rilpivirine formulation is under-development for pre-exposure prophylaxis. Given their widespread use, particularly in resource-limited settings, as well as their low genetic barriers to resistance, there are concerns about overlapping resistance between the different NNRTIs. Consequently, a better understanding of the resistance and cross-resistance profiles among the NNRTI class is important for predicting response to treatment, and surveillance of transmitted drug-resistance.

2,4,5-Trisubstituted thiazole derivatives: A novel and potent class of non-nucleoside inhibitors of wild type and mutant HIV-1 reverse transcriptase

Novel 2,4,5-trisubstituted thiazole derivatives (TSTs) were designed and synthesized as HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Among the thirty-eight synthesized target compounds, thirty TSTs showed potent inhibition against HIV-1 replication in wild type HIV-1 at submicromolar concentrations (from 0.046 to 9.59 μM). Compounds 21, 23 and 24 were also tested on seven NNRTI-resistant HIV-1 strains, and all exhibited inhibitory effects with fold changes in IC50 ranging from 2.6 to 111, which were better than those of nevirapine (15.6-fold–371-fold). Docking simulations of compound 24 revealed a reasonable mechanism for the binding mode, and three-dimensional quantitative structure activity relationship (3-DQSAR) studies on this novel series of TST further elucidated the structure–activity relationship (SAR). The results suggested the great potential of TSTs as a novel class of NNRTIs with antiviral efficacy and a good resistance profile.

Profile of etravirine in the treatment of HIV in pediatrics

Profile of etravirine in the treatment of HIV in pediatrics Walter Dehority,1 Rolando M Viani2 1Department of Pediatrics, Division of Infectious Diseases, The University of New Mexico Health Sciences Center, University of New Mexico, Albuquerque, NM, USA; 2Department of Pediatrics, Division of Infectious Diseases, Center for AIDS Research, University of California, San Diego School of Medicine, Rady Children&#39;s Hospital, San Diego, CA, USA Abstract: Etravirine is a non-nucleoside reverse transcriptase inhibitor now licensed for treatment of human immunodeficiency virus (HIV)-1 infection in both children over 6 years of age and adults. Etravirine demonstrates a high genetic barrier to the development of resistance, as multiple mutations are typically required prior to the onset of reduced susceptibility to the drug. It retains in vitro and clinical activity against many HIV-1 isolates, demonstrating resistance to other non-nucleoside reverse transcriptase inhibitors, such as efavirenz and nevirapine. Given the ability of HIV to develop resistance rapidly across the non-nucleoside reverse transcriptase inhibitor class of antiretrovirals, etravirine has a welcome place in the management of HIV-infected patients, particularly treatment-experienced individuals harboring non-nucleoside reverse transcriptase inhibitor mutations. Etravirine has been shown to improve CD4 counts and viral load significantly in HIV-infected adults on combination antiretroviral therapy when compared with placebo in a large, randomized controlled trial. Data on the utility of etravirine in children are still somewhat limited, although a recent pediatric trial has demonstrated adequate pharmacokinetics, safety, and efficacy of etravirine in a small number of HIV-infected children and adolescents. In both children and adults, rash appears to be the most common adverse effect described. Despite its high genetic barrier to resistance, evidence of mutations conferring etravirine resistance has been documented in both adult and pediatric patients. Such mutations have been best described in treatment-experienced populations, including those who have never been exposed to the drug. This review describes the existing literature on the use of etravirine in the pediatric population, and highlights future and ongoing directions of investigation. Keywords: etravirine, pediatric, human immunodeficiency virus, antiretrovirals, non-nucleoside reverse transcriptase inhibitor

Discovery of Phenylaminopyridine Derivatives as Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors.

We identified a novel class of aryl-substituted triazine compounds as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) during a high-throughput screening campaign that evaluated more than 200000 compounds for antihuman immunodeficiency virus (HIV) activity using a cell-based full replication assay. Herein, we disclose the optimization of the antiviral activity in a cell-based assay system leading to the discovery of compound 27, which possessed excellent potency against wild-type HIV-1 (EC50 = 0.2 nM) as well as viruses bearing Y181C and K103N resistance mutations in the reverse transcriptase gene. The X-ray crystal structure of compound 27 complexed with wild-type reverse transcriptase confirmed the mode of action of this novel class of NNRTIs. Introduction of a chloro functional group in the pyrazole moiety dramatically improved hERG and CYP inhibition profiles, yielding highly promising leads for further development.

Epidemiology of Transmitted Drug Resistance in Chronically HIV-Infected Patients in Germany: The RESINA Study 2001–2009

Objectives: Transmitted HIV drug resistance may impair treatment efficacy of combination antiretroviral therapy (ART). This study describes the epidemiology of transmitted resistance in chronically infected patients. Methods: In a prospective multicenter trial in Nordrhein-Westfalen, Germany, transmitted drug resistance was determined by genotypic resistance testing in patients on initiation of first-line ART. Results: From 2001 to 2009, 2,078 patients were enrolled in the study. 79.9% were male, 81.2% were Caucasians, and a homosexual transmission mode was found in 51.3%. Of these patients, 41.5% were at the stage of AIDS, median CD4 cell count was 230/µl, and median viral load was 64.466 copies/ml. Transmitted drug resistance mutations were seen in 9.2% (95% CI, 7.9–10.4). Resistance in the nucleoside reverse transcriptase inhibitor class was found in 5.8% (4.8–6.8), in the nonnucleoside reverse transcriptase inhibitor class in 2.8% (2.1–3.6), and in the protease inhibitor class in 2.7% (2.0–3.4). After a continuous increase to a level above 10% in the years 2006 and 2007, a decline of drug resistance prevalence followed in 2008 and 2009. Conclusions: Transmitted HIV drug resistance was found in around 10% of chronically infected patients in Germany who started their ART. We showed a moderate decline of the prevalence of mutant virus strains in recent years. Further surveillance of this phenomenon is mandatory.

Reverse Transcriptase Inhibitors as Microbicides

The CAPRISA 004 study in South Africa has accelerated the development of vaginal and rectal microbicides containing antiretrovirals that target specific enzymes in the reproduction cycle of HIV, especially reverse transcriptase inhibitors (RTI). In this review we discuss the potential relevance of HIV-1 RTIs as microbicides, focusing in the nucleotide RTI tenofovir and six classes of nonnucleoside RTIs (including dapivirine, UC781, urea and thiourea PETTs, DABOs and a pyrimidinedione). Although tenofovir and dapivirine appear to be most advanced in clinical trials as potential microbicides, several issues remain unresolved, e.g., the importance of nonhuman primates as a "gatekeeper" for clinical trials, the emergence and spread of drug-resistant mutants, the combination of microbicides that target different phases of viral reproduction and the accessibility to microbicides in low-income countries. Thus, here we discuss the latest research on RTI as microbicides in the light of the continuing spread of the HIV pandemic from the point of view of medicinal chemistry, virological, and pharmaceutical studies.