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1.  Nonnucleoside Reverse Transcriptase Inhibitor-Resistant HIV Is Stimulated by Efavirenz during Early Stages of Infection ▿  
Journal of Virology  2011;85(20):10861-10873.
Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are potent and commonly prescribed antiviral agents used in combination therapy (CART) of human immunodeficiency virus type 1 (HIV-1) infection. The development of drug resistance is a major limitation of CART. Reverse transcriptase (RT) genotypes with the NNRTI resistance mutations K101E+G190S are highly resistant to efavirenz (EFV) and can develop during failure of EFV-containing regimens in patients. We have previously shown that virus with K101E+G190S mutations can replicate more efficiently in the presence of EFV than in its absence. In this study, we evaluated the underlying mechanism for drug-dependent stimulation, using a single-cycle cell culture assay in which EFV was added either during the infection or the virus production step. We determined that EFV stimulates K101E+G190S virus during early infection and does not affect late steps of virus replication, such as increasing the amount of active RT incorporated into virions. Additionally, we showed that another NNRTI, nevirapine (NVP), stimulated K101E+G190S virus replication during the early steps of infection similar to EFV, but that the newest NNRTI, etravirine (ETR), did not. We also showed that EFV stimulates K101E+Y188L and K101E+V106I virus, but not K101E+L100I, K101E+K103N, K101E+Y181C, or K101E+G190A virus, suggesting that the stimulation is mutation specific. Real-time PCR of reverse transcription intermediates showed that although the drug did not stimulate minus-strand transfer, it did stimulate minus-strand strong-stop DNA synthesis. Our results indicate that stimulation most likely occurs through a mechanism whereby NNRTIs stimulate priming or elongation of the tRNA.
PMCID: PMC3187512  PMID: 21835788
2.  A Tight-Binding Mode of Inhibition Is Essential for Anti-Human Immunodeficiency Virus Type 1 Virucidal Activity of Nonnucleoside Reverse Transcriptase Inhibitors 
It was previously found that certain nonnucleoside reverse transcriptase inhibitors (NNRTI) possess virucidal activity against human immunodeficiency virus type 1 (HIV-1), and it was suggested that the tight-binding mode of inhibition of reverse transcriptase might be important for this virucidal activity (Borkow et al., J. Virol. 71:3023-3030, 1997). To test this, we compared six different NNRTI, including three tight-binding NNRTI, namely UC781, efavirenz (EFV) (Sustiva), and 5-chloro-3-phenylsulfonylindole-2-carboxamide (CSIC), and three rapid-equilibrium NNRTI, delavirdine (DLV) (Rescriptor), nevirapine (NVP) (Viramune), and UC84, in a variety of virucidal tests. Incubation of isolated HIV-1 virions with UC781, EFV, or CSIC rapidly inactivated the virus, whereas DLV, NVP, and UC84 were ineffective in this respect. Exposure of H9+ cells chronically infected by HIV-1 to the tight-binding NNRTI abolished the infectivity of nascent virus subsequently produced by these cells following removal of extracellular drug, thereby preventing cell-to-cell virus transmission in the absence of exogenous drug. In contrast, cell-to-cell transmission of HIV was blocked by DLV, NVP, and UC84 only when the drug remained in the extracellular medium. Pretreatment of uninfected lymphocytoid cells with UC781, EFV, or CSIC, but not DLV, NVP, or UC84, protected these cells from subsequent HIV-1 infection in the absence of extracellular drug. The protective effect was dependent on both the dose of NNRTI and the viral load. The overall virucidal efficacy of the tight-binding NNRTI tested was CSIC > UC781 ≃ EFV. We conclude that the tight-binding mode of inhibition is an essential characteristic for virucidal NNRTI and that antiviral potency is an insufficient predictor for virucidal utility of NNRTI.
PMCID: PMC127238  PMID: 12019100
3.  Inhibition of endogenous reverse transcription of human and nonhuman primate lentiviruses: Potential for development of lentivirucides 
Virology  2006;353(2):482-490.
In the current study, we extended our previous works on natural endogenous reverse transcription (NERT) and further examined its potential as a virucide molecular target in sexual transmission of primate lentiviruses. HIV-1 and SIV virions were pretreated with select nucleoside (NRTIs) and nonnucleoside RT inhibitors (NNRTIs), either alone or in combination with NERT-stimulating substances. The effects of these antiretrovirals on virion inactivation were analyzed in human T cell lines and primary cell cultures. Pretreatment of HIV-1 virions with physiologic NERT-stimulants and 3′-azido-3′-deoxythymidine 5′-triphosphate (AZT-TP) or nevirapine potently inactivated cell-free HIV-1 virions and resulted in strong inhibition of the viral infectivity. Pretreatment of chimeric SHIV-RT virions with NERT-stimulating cocktail and select antiretrovirals also resulted in virion inactivation and inhibition of viral infectivity in T cell lines. Our findings demonstrate the potential clinical utility of approaches based on inhibiting NERT in sexual transmission of HIV-1, through the development of effective anti-HIV-1 microbicides, such as NRTIs and NNRTIs.
PMCID: PMC1626530  PMID: 16859727
4.  Amino Acid Substitutions at Position 190 of Human Immunodeficiency Virus Type 1 Reverse Transcriptase Increase Susceptibility to Delavirdine and Impair Virus Replication 
Journal of Virology  2003;77(2):1512-1523.
Suboptimal treatment of human immunodeficiency virus type 1 (HIV-1) infection with nonnucleoside reverse transcriptase inhibitors (NNRTI) often results in the rapid selection of drug-resistant virus. Several amino acid substitutions at position 190 of reverse transcriptase (RT) have been associated with reduced susceptibility to the NNRTI, especially nevirapine (NVP) and efavirenz (EFV). In the present study, the effects of various 190 substitutions observed in viruses obtained from NNRTI-experienced patients were characterized with patient-derived HIV isolates and confirmed with a panel of isogenic viruses. Compared to wild-type HIV, which has a glycine at position 190 (G190), viruses with 190 substitutions (A, C, Q, S, V, E, or T, collectively referred to as G190X substitutions) were markedly less susceptible to NVP and EFV. In contrast, delavirdine (DLV) susceptibility of these G190X viruses increased from 3 to 300-fold (hypersusceptible) or was only slightly decreased. The replication capacity of viruses with certain 190 substitutions (C, Q, V, T, and E) was severely impaired and was correlated with reduced virion-associated RT activity and incomplete protease (PR) processing of the viral p55gag polyprotein. These defects were the result of inadequate p160gagpol incorporation into virions. Compensatory mutations within RT and PR improved replication capacity, p55gag processing, and RT activity, presumably through increased incorporation of p160gagpol into virions. We observe an inverse relationship between the degree of NVP and EFV resistance and the impairment of viral replication in viruses with substitutions at 190 in RT. These observations may have important implications for the future design and development of antiretroviral drugs that restrict the outgrowth of resistant variants with high replication capacity.
PMCID: PMC140843  PMID: 12502865
5.  Non-nucleoside reverse transcriptase inhibitor efavirenz increases monolayer permeability of human coronary artery endothelial cells 
Atherosclerosis  2009;208(1):104.
Highly active antiretroviral therapy (HAART) is often associated with endothelial dysfunction and cardiovascular complications. In this study, we determined whether HIV non-nucleoside reverse transcriptase inhibitor efavirenz (EFV) could increase endothelial permeability. Human coronary artery endothelial cells (HCAECs) were treated with EFV (1, 5 and 10 µg/ml) and endothelial permeability was determined by a transwell system with a fluorescence-labeled dextran tracer. HCAECs treated with EFV showed a significant increase of endothelial permeability in a concentration-dependent manner. With real time PCR analysis, EFV significantly reduced the mRNA levels of tight junction proteins claudin-1, occludin, zonula occluden-1 and junctional adhesion molecule-1 compared with controls (P < 0.05). Protein levels of these tight junction molecules were also reduced substantially in the EFV-treated cells by western blot and flow cytometry analyses. In addition, EFV also increased superoxide anion production with dihydroethidium and cellular glutathione assays, while it decreased mitochondrial membrane potential with JC-staining. Antioxidants (ginkgolide B and MnTBAP) effectively blocked EFV-induced endothelial permeability and mitochondrial dysfunction. Furthermore, EFV increased the phosphorylation of MAPK JNK and IκBα, thereby increasing NFκB translocation to the nucleus. Chemical JNK inhibitor and dominant negative mutant JNK and IkBa adenoviruses effectively blocked the effects of EFV on HCAECs. Thus, EFV increases endothelial permeability which may be due to the decrease of tight junction proteins and the increase of superoxide anion. JNK and NFκB activation may be directly involved in the signal transduction pathway of EFV action in HCAECs.
PMCID: PMC2813420  PMID: 19674747
Efavirenz; HAART; endothelial permeability; tight junction protein; oxidative stress; antioxidant; ginkgolide B; MnTBAP; JNK; NFκB
6.  Restoration of Wild-Type Infectivity to Human Immunodeficiency Virus Type 1 Strains Lacking nef by Intravirion Reverse Transcription 
Journal of Virology  2001;75(24):12081-12087.
Human immunodeficiency virus type 1 (HIV-1) Nef protein exerts several effects, both on infected cells and as a virion protein, which work together to enhance viral replication. One of these activities is the ability to enhance infectivity and the formation of proviral DNA. The mechanism of this enhancement remains incompletely understood. We show that virions with nef deleted can be restored to wild-type infectivity by stimulating intravirion reverse transcription. Particle composition and measures of reverse transcriptase activity remain the same for Nef+ and Nef− virions both before and after natural endogenous reverse transcription (NERT) treatment. The effect of NERT treatment on virions pseudotyped with murine leukemia virus envelope protein was similar to that on particles pseudotyped with HIV-1 envelope protein. However, virions pseudotyped with vesicular stomatitis virus G envelope protein showed no influence of Nef on NERT enhancement of infectivity. These observations suggest that Nef may function at a level prior to reverse transcription. Since NERT treatment results in partial disassembly of the viral core, we speculate that Nef may function at the level of core particle disassembly.
PMCID: PMC116103  PMID: 11711598
7.  Nevirapine and Efavirenz Elicit Different Changes in Lipid Profiles in Antiretroviral- Therapy-Naive Patients Infected with HIV-1 
PLoS Medicine  2004;1(1):e19.
Patients infected with HIV-1 initiating antiretroviral therapy (ART) containing a non-nucleoside reverse transcriptase inhibitor (NNRTI) show presumably fewer atherogenic lipid changes than those initiating most ARTs containing a protease inhibitor. We analysed whether lipid changes differed between the two most commonly used NNRTIs, nevirapine (NVP) and efavirenz (EFV).
Methods and Findings
Prospective analysis of lipids and lipoproteins was performed in patients enrolled in the NVP and EFV treatment groups of the 2NN study who remained on allocated treatment during 48 wk of follow-up. Patients were allocated to NVP (n = 417), or EFV (n = 289) in combination with stavudine and lamivudine. The primary endpoint was percentage change over 48 wk in high-density lipoprotein cholesterol (HDL-c), total cholesterol (TC), TC:HDL-c ratio, non-HDL-c, low-density lipoprotein cholesterol, and triglycerides. The increase of HDL-c was significantly larger for patients receiving NVP (42.5%) than for patients receiving EFV (33.7%; p = 0.036), while the increase in TC was lower (26.9% and 31.1%, respectively; p = 0.073), resulting in a decrease of the TC:HDL-c ratio for patients receiving NVP (−4.1%) and an increase for patients receiving EFV (+5.9%; p < 0.001). The increase of non-HDL-c was smaller for patients receiving NVP (24.7%) than for patients receiving EFV (33.6%; p = 0.007), as were the increases of triglycerides (20.1% and 49.0%, respectively; p < 0.001) and low-density lipoprotein cholesterol (35.0% and 40.0%, respectively; p = 0.378). These differences remained, or even increased, after adjusting for changes in HIV-1 RNA and CD4+ cell levels, indicating an effect of the drugs on lipids over and above that which may be explained by suppression of HIV-1 infection. The increases in HDL-c were of the same order of magnitude as those seen with the use of the investigational HDL-c-increasing drugs.
NVP-containing ART shows larger increases in HDL-c and decreases in TC:HDL-c ratio than an EFV-containing regimen. Based on these findings, protease-inhibitor-sparing regimens based on non-nucleoside reverse transcriptase inhibitor, particularly those containing NVP, may be expected to result in a reduced risk of coronary heart disease.
Comparison of two commonly prescribed non-nucleoside reverse transcriptase inhibitors shows that patients on nevirapine have better blood lipid profiles
PMCID: PMC523838  PMID: 15526045
8.  Impact of Y181C and/or H221Y mutation patterns of HIV-1 reverse transcriptase on phenotypic resistance to available non-nucleoside and nucleoside inhibitors in China 
BMC Infectious Diseases  2014;14:237.
The aim of this study was to investigate the role of K101Q, Y181C and H221Y emerging in HIV-1 reverse transcriptase with different mutations patterns in phenotypic susceptibility to currently available NNRTIs (nevirapine NVP, efavirenz EFV) and NRTIs (zidovudine AZT, lamivudine 3TC, stavudine d4T) in China.
Phenotype testing of currently available NNRTIs (NVP, EFV) and NRTIs (AZT, 3TC, d4T) was performed on TZM-b1 cells using recombined virus strains. P ≤ 0.05 was defined significant considering the change of 50% inhibitory drug concentration (IC50) compared with the reference, while P ≤ 0.01 was considered to be statistically significant considering multiple comparisons.
Triple-mutation K101Q/Y181C/H221Y and double-mutation K101Q/Y181C resulted in significant increase in NVP resistance (1253.9-fold and 986.4-fold), while only K101Q/Y181C/H221Y brought a 5.00-fold significant increase in EFV resistance. Remarkably, K101Q/H221Y was hypersusceptible to EFV (FC = 0.04), but was significantly resistant to the three NRTIs. Then, the interaction analysis suggested the interaction was not significant to NVP (F = 0.77, P = 0.4061) but significant to EFV and other three NRTIs.
Copresence of mutations reported to be associated with NNRTIs confers significant increase to NVP resistance. Interestingly, some may increase the susceptibility to EFV. Certainly, the double mutation (K101Q/H221Y) also changes the susceptibility of viruses to NRTIs. Interaction between two different sites makes resistance more complex.
PMCID: PMC4024112  PMID: 24885612
Nucleoside reverse transcriptase inhibitors (NRTIs); Non-nucleoside reverse transcriptase inhibitors (NNRTIs); HIV-1 resistance mutation; 50% inhibitory drug concentration
9.  Efficacy of Short-Course AZT Plus 3TC to Reduce Nevirapine Resistance in the Prevention of Mother-to-Child HIV Transmission: A Randomized Clinical Trial 
PLoS Medicine  2009;6(10):e1000172.
Neil Martinson and colleagues report a randomized trial of adding short-course zidovudine+lamivudine to reduce drug resistance from single-dose nevirapine used to prevent mother-to-child transmission of HIV.
Single-dose nevirapine (sdNVP)—which prevents mother-to-child transmission of HIV—selects non-nucleoside reverse-transcriptase inhibitor (NNRTI) resistance mutations in the majority of women and HIV-infected infants receiving it. This open-label, randomised trial examined the efficacy of short-course zidovudine (AZT) and lamivudine (3TC) with sdNVP in reducing NNRTI resistance in mothers, and as a secondary objective, in infants, in a setting where sdNVP was standard-of-care.
Methods and Findings
sdNVP alone, administered at the onset of labour and to the infant, was compared to sdNVP with AZT plus 3TC, given as combivir (CBV) for 4 (NVP/CBV4) or 7 (NVP/CBV7) days, initiated simultaneously with sdNVP in labour; their newborns received the same regimens. Women were randomised 1∶1∶1. HIV-1 resistance was assessed by population sequencing at: baseline, 2, and 6 wk after birth. An unplanned interim analysis resulted in early stopping of the sdNVP arm. 406 pregnant women were randomised and took study medication (sdNVP 74, NVP/CBV4 164, and NVP/CBV7 168). HIV-1 resistance mutations emerged in 59.2%, 11.7%, and 7.3% of women in the sdNVP, NVP/CBV4, and NVP/CBV7 arms by 6 wk postpartum; differences between NVP-only and both NVP/CBV arms were significant (p<0.0001), but the difference between NVP/CBV4 and NVP/CBV7 was not (p = 0.27). Estimated efficacy comparing combined CBV arms with sdNVP was 85.6%. Similar resistance reductions were seen in infants who were HIV-infected by their 6-wk visit.
A short course of AZT plus 3TC, supplementing maternal and infant sdNVP, reduces emergent NNRTI resistance mutations in both mothers and their infants. However, this trial was not powered to detect small differences between the CBV arms.
Trial registration NCT 00144183
Please see later in the article for the Editors' Summary
Editors' Summary
Currently, about 33 million people are infected with the human immunodeficiency virus (HIV), which causes AIDS. HIV can be treated with combination antiretroviral therapy (ART), commonly three individual antiretroviral drugs that together efficiently suppress the replication of the virus. HIV infection of a child by an HIV-positive mother during pregnancy, labor, delivery, or breastfeeding is called mother-to-child transmission (MTCT). In 2007, an estimated 420,000 children were newly infected with HIV, the majority through MTCT. Most of these mothers and children live in sub-Saharan Africa where child and maternal mortality rates are high and mortality in HIV-infected children is extremely high. MTCT is preventable and there is a global commitment, agreed at the UN General Assembly Session on HIV/AIDS in 2001, to reduce the proportion of infants infected with HIV by 50% by 2010.
Why Was This Study Done?
In many resource-limited settings, MTCT is prevented by giving a single dose of nevirapine (an antiretroviral drug which has a long duration in the body and protects the fetus during labor and delivery only) to HIV-infected women in labor and also to a baby within 72 hours of birth. However, nevirapine, a non-nucleoside reverse-transcriptase inhibitor (NNRTI), which suppresses the replication of the virus, is associated with increased resistance of HIV, in mother and child, to NNRTI. This resistance reduces the effectiveness of future treatments of both mother and child with combination ART that includes an NNRTI; such regimens are the mainstay for long-term treatment of HIV in developing countries. The researchers investigated whether giving other antiretroviral drugs with nevirapine, during labor and delivery, to both mother and her newborn reduced the chances of them developing resistance to NNRTIs.
What Did the Researchers Do and Find?
The researchers selected 406 HIV-positive pregnant women for study across five sites in South Africa between February 2003 and May 2007. The women and their newborn babies were randomly assigned to receive, either (i) a single dose of nevirapine, (ii) a single dose of nevirapine plus combivir (zidovudine combined with lamivudine) for four days, or (iii) a single dose of nevirapine plus combivir for seven days. At two days, two weeks, and six weeks after delivery blood was collected from mothers and babies. HIV virus from blood samples was analyzed for resistance mutations, and mothers and children with resistance mutations were monitored for a further 96 weeks until no resistance was detected or combination ART (also called “HAART”) was started. Enrollment into the single-dose nevirapine arm was stopped early because a very high rate of NNRTI resistance mutations was found and other investigators reported long-term bad consequences of NNRTI-resistance on subsequent ART. The two nevirapine plus combivir arms were continued. The researchers found that selection of resistance mutations by single-dose nevirapine was reduced in mother and child by the addition of zidovudine and lamivudine for a short period; resistance mutations were found in 59.2% of women who got nevirapine only but only 11.7%, and 7.3% of women treated nevirapine plus four days combivir, and nevirapine plus seven days combivir respectively. A reduction was also seen in new NNRTI resistant mutations in the HIV-infected infants that received combivir. The study did not have enough women to show that there was a real difference between the resistance in the four-day and seven-day combivir regimens.
What Do These Findings Mean?
These findings show that a short-course treatment of zidovudine and lamivudine in addition to a single dose of nevirapine during labor and birth reduces the selection of NNRTI resistance mutations in both mother and child. The drug regimens appeared safe, and easy to provide and adhere to. Preliminary results from this study contributed to a change in clinical practice for the care of pregnant women with HIV; in 2004 the World Health Organisation guidelines introduced a short course of combivir with nevirapine for the management of pregnant HIV-infected women. However, the study had some limitations. It used HIV-positive women who were mainly infected with a subtype of HIV called HIV-1 clade C and who had a lot of virus in their blood. NNRTI resistance after treatment with nevirapine is more common in clade C than in others and this study does not address the effect of these combinations for preventing NNRTI resistance in other HIV subtypes. Also, World Health Organization, national, and international guidelines recommend combination ART during pregnancy, as it decreases HIV transmission from mother to child in the uterus to <2% in resource-limited settings. Although long-term combination treatment may not be available in all locations, this study does not tell us how the short-term combinations during and after delivery tested would compare to longer-term combinations given to pregnant women in reducing both HIV transmission and HIV drug resistance.
Additional Information
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Lehman et al.
The US Centers for Disease Control and Prevention provide information for HIV treatment and prevention
MedlinePlus provides extensive information on symptoms and treatment for HIV/AIDS as well as access to related clinical trials and medical literature
aidsmap, a nonprofit, nongovernmental organization provides information on HIV and supporting those living with HIV
The World Health Organization gives information on the prevention of mother-to-child transmission of HIV
PMCID: PMC2760761  PMID: 19859531
10.  The M230L Nonnucleoside Reverse Transcriptase Inhibitor Resistance Mutation in HIV-1 Reverse Transcriptase Impairs Enzymatic Function and Viral Replicative Capacity▿  
The M230L mutation in HIV-1 reverse transcriptase (RT) is associated with resistance to first-generation nonnucleoside reverse transcriptase inhibitors (NNRTIs). The present study was designed to determine the effects of M230L on enzyme function, viral replication capacity (RC), and the extent to which M230L might confer resistance to the second-generation NNRTI etravirine (ETR) as well as to the first-generation NNRTIs efavirenz (EFV) and nevirapine (NVP). Phenotyping assays with TZM-bl cells confirmed that M230L conferred various degrees of resistance to each of the NNRTIs tested. Recombinant viruses containing M230L displayed an 8-fold decrease in RC compared to that of the parental wild-type (WT) virus. Recombinant HIV-1 WT and M230L mutant RT enzymes were purified; and both biochemical and cell-based phenotypic assays confirmed that M230L conferred resistance to each of EFV, NVP, and ETR. RT that contained M230L was also deficient in regard to each of minus-strand DNA synthesis, both DNA- and RNA-dependent polymerase activities, processivity, and RNase H activity, suggesting that this mutation contributes to diminished viral replication kinetics.
PMCID: PMC2876396  PMID: 20308384
11.  Rilpivirine versus etravirine validity in NNRTI-based treatment failure in Thailand 
Journal of the International AIDS Society  2014;17(4Suppl 3):19740.
Etravirine (ETR) and rilpivirine (RPV) are the second-generation non-nucleoside reverse transcriptase inhibitors (NNRTI) for treatment of HIV-1 infection. Etravirine is recommended for patients with virologic failure from first generation NNRTI-based regimen [1]. RPV has profile with similar properties to ETR but this agent is approved for treatment-naïve patients [2]. In Thailand, ETR is approximately 45 times more expensive than RPV. We aimed to study the patterns of genotypic resistance and possibility of using RPV in patients with virologic failure from two common NNRTI-based regimens: efavirenz (EFV)- or nevirapine (NVP)-based regimen.
Materials and Methods
Data of clinical samples with confirmed virologic failure during 2003–2010 were reviewed. We selected the samples from patients who failed EFV- or NVP-based regimen. Resistance-associated mutations (RAMs) were determined by IAS-USA Drug Resistance Mutations. DUET, Monogram scoring system and Stanford Genotypic Resistance Interpretation were applied to determine the susceptibility of ETR and RPV.
A total of 2086 samples were analyzed. Samples from 1482 patients with virologic failure from NVP-based regimen treatment failure (NVP group) and 604 patients with virologic failure from EFV-based regimen treatment failure (EFV group) were included. 95% of samples were HIV-1 CRF01_AE subtype. Approximately 80% of samples in each group had one to three NNRTI-RAMs and 20% had four to seven NNRTI-RAMs. 181C mutation was the most common NVP-associated RAM (54.3% vs 14.7%, p<0.01). 103N mutation was the most common EFV-associated RAM (56.5% vs 19.1%, p<0.01). The calculated scores from all three scoring systems were concordant. In NVP group, 165 (11.1%) and 161 (10.9%) patients were susceptible to ETR and RPV, respectively (p=0.81). In EFV group, 195 (32.2%) and 191 (31.6%) patients were susceptible to ETR and RPV, respectively (p=0.81). The proportions of viruses that remained susceptible to ETR and RPV in EFV group were significantly higher than NPV group (ETR susceptibility 32.2% vs 11.1%, p<0.01, RPV susceptibility 31.6% vs 10.9%, p<0.01), respectively.
RPV might be a cost saving and reasonable second line NNRTI for patients who failed EFV- or NVP-containing regimens, especially in resource-limited setting because these two agents have comparable susceptibility identified by genotyping. From our study, approximately 30% of patients who failed EFV-based regimens had viruses that remained susceptible to RPV.
PMCID: PMC4225409  PMID: 25397485
12.  Altered Viral Fitness and Drug Susceptibility in HIV-1 Carrying Mutations That Confer Resistance to Nonnucleoside Reverse Transcriptase and Integrase Strand Transfer Inhibitors 
Journal of Virology  2014;88(16):9268-9276.
Nonnucleoside reverse transcriptase (RT) inhibitors (NNRTI) and integrase (IN) strand transfer inhibitors (INSTI) are key components of antiretroviral regimens. To explore potential interactions between NNRTI and INSTI resistance mutations, we investigated the combined effects of these mutations on drug susceptibility and fitness of human immunodeficiency virus type 1 (HIV-1). In the absence of drug, single-mutant viruses were less fit than the wild type; viruses carrying multiple mutations were less fit than single-mutant viruses. These findings were explained in part by the observation that mutant viruses carrying NNRTI plus INSTI resistance mutations had reduced amounts of virion-associated RT and/or IN protein. In the presence of efavirenz (EFV), a virus carrying RT-K103N together with IN-G140S and IN-Q148H (here termed IN-G140S/Q148H) mutations was fitter than a virus with a RT-K103N mutation alone. Similarly, in the presence of EFV, the RT-E138K plus IN-G140S/Q148H mutant virus was fitter than one with the RT-E138K mutation alone. No effect of INSTI resistance mutations on the fitness of RT-Y181C mutant viruses was observed. Conversely, RT-E138K and -Y181C mutations improved the fitness of the IN-G140S/Q148H mutant virus in the presence of raltegravir (RAL); the RT-K103N mutation had no effect. The NNRTI resistance mutations had no effect on RAL susceptibility. Likewise, the IN-G140S/Q148H mutations had no effect on EFV or RPV susceptibility. However, both the RT-K103N plus IN-G140S/Q148H and the RT-E138K plus IN-G140S/Q148H mutant viruses had significantly greater fold increases in 50% inhibitory concentration (IC50) of EFV than viruses carrying a single NNRTI mutation. Likewise, the RT-E138K plus IN-G140S/Q148H mutant virus had significantly greater fold increases in RAL IC50 than that of the IN-G140S/Q148H mutant virus. These results suggest that interactions between RT and IN mutations are important for NNRTI and INSTI resistance and viral fitness.
IMPORTANCE Nonnucleoside reverse transcriptase inhibitors and integrase inhibitors are used to treat infection with HIV-1. Mutations that confer resistance to these drugs reduce the ability of HIV-1 to reproduce (that is, they decrease viral fitness). It is known that reverse transcriptase and integrase interact and that some mutations can disrupt their interaction, which is necessary for proper functioning of these two enzymes. To determine whether resistance mutations in these enzymes interact, we investigated their effects on drug sensitivity and viral fitness. Although individual drug resistance mutations usually reduced viral fitness, certain combinations of mutations increased fitness. When present in certain combinations, some integrase inhibitor resistance mutations increased resistance to nonnucleoside reverse transcriptase inhibitors and vice versa. Because these drugs are sometimes used together in the treatment of HIV-1 infection, these interactions could make viruses more resistant to both drugs, further limiting their clinical benefit.
PMCID: PMC4136249  PMID: 24899199
13.  Human Immunodeficiency Virus Type 1 Resistance or Cross-Resistance to Nonnucleoside Reverse Transcriptase Inhibitors Currently under Development as Microbicides ▿ †  
Microbicides based on nonnucleoside reverse transcriptase inhibitors (NNRTIs) are currently being developed to protect women from HIV acquisition through sexual contact. However, the large-scale introduction of these products raises two major concerns. First, when these microbicides are used by undiagnosed HIV-positive women, they could potentially select for viral resistance, which may compromise subsequent therapeutic options. Second, NNRTI-based microbicides that are inactive against NNRTI-resistant strains might promote the selective transmission of these viruses. In order to address these concerns, drug resistance was selected in vitro by the serial passage of three viral isolates from subtypes B and C and CRF02_AG (a circulating recombinant form) in activated peripheral blood mononuclear cells (PBMCs) under conditions of increasing concentrations of three NNRTIs (i.e., TMC120, UC781, and MIV-160) that are currently being developed as candidate microbicides. TMC120 and MIV-160 displayed a high genetic barrier to resistance development, whereas resistance to UC781 emerged rapidly, similarly to efavirenz and nevirapine. Phenotypically, the selected viruses appeared to be highly cross-resistant to current first-line therapeutic NNRTIs (i.e., delavirdine, nevirapine, and efavirenz), although they retained some susceptibility to the more recently developed NNRTIs lersivirine and etravirine. The ability of UC781, TMC120, and MIV-160 to inhibit the in vitro-selected NNRTI-resistant viruses was also limited, although residual activity could be observed for the candidate microbicide NNRTI MIV-170. Interestingly, only four p2/p7/p1/p6/PR/RT/INT recombinant NNRTI-resistant viruses (i.e., TMC120-resistant VI829, EFV-resistant VI829, MIV-160-resistant VI829, and EFV-resistant MP568) showed impairments in replicative fitness. Overall, these in vitro analyses demonstrate that due to potential cross-resistance, the large-scale introduction of single-NNRTI-based microbicides should be considered with caution.
PMCID: PMC3067143  PMID: 21282453
14.  Combination of V106I and V179D Polymorphic Mutations in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Efavirenz and Nevirapine but Not Etravirine▿ †  
Etravirine (ETV) is a second-generation nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) introduced recently for salvage antiretroviral treatment after the emergence of NNRTI-resistant human immunodeficiency virus type 1 (HIV-1). Following its introduction, two naturally occurring mutations in HIV-1 RT, V106I and V179D, were listed as ETV resistance-associated mutations. However, the effect of these mutations on the development of NNRTI resistance has not been analyzed yet. To select highly NNRTI-resistant HIV-1 in vitro, monoclonal HIV-1 strains harboring V106I and V179D (HIV-1V106I and HIV-1V179D) were propagated in the presence of increasing concentrations of efavirenz (EFV). Interestingly, V179D emerged in one of three selection experiments from HIV-1V106I and V106I emerged in two of three experiments from HIV-1V179D. Analysis of recombinant HIV-1 clones showed that the combination of V106I and V179D conferred significant resistance to EFV and nevirapine (NVP) but not to ETV. Structural analysis indicated that ETV can overcome the repulsive interactions caused by the combination of V106I and V179D through fine-tuning of its binding module to RT facilitated by its plastic structure, whereas EFV and NVP cannot because of their rigid structures. Analysis of clinical isolates showed comparable drug susceptibilities, and the same combination of mutations was found in some database patients who experienced virologic NNRTI-based treatment failure. The combination of V106I and V179D is a newly identified NNRTI resistance pattern of mutations. The combination of polymorphic and minor resistance-associated mutations should be interpreted carefully.
PMCID: PMC2849364  PMID: 20124001
15.  Endogenous reverse transcription of human immunodeficiency virus type 1 in physiological microenviroments: an important stage for viral infection of nondividing cells. 
Journal of Virology  1996;70(5):2809-2824.
Endogenous reverse transcription (ERT) of retroviruses has long been considered a somewhat artificial process which only mimics reverse transcription occurring in target cells, as detergents or amphipathic peptides have classically been used to make the envelopes of retroviruses in these reaction systems permeable. Recently, several studies suggested that ERT of human immunodeficiency virus type 1 (HIV-1) might occur without detergent treatment. However, this phenomenon could be due to damage of the retroviral envelope during the process of virion purification or freezing and thawing. In this report, intravirion HIV-1 ERT, without detergent-induced permeabilization, is demonstrated to occur in the natural microenvironments of HIV-1 virions and is not caused by artificial processes. Therefore, this stage of the viral life cycle was termed natural ERT (NERT). The efficiency of NERT in HIV-1 virions was markedly augmented by several physiological substances in the extracellular milieu, such as polyamines and deoxyribonucleoside triphosphates. In addition, HIV-1 virions in seminal plasma samples harbored dramatically higher levels of full-length or nearly full-length reverse transcripts than virions isolated from peripheral blood plasma samples of HIV-1-seropositive men. When HIV-1 virions were incubated with seminal plasma samples, infectivity in initially nondividing cells was also significantly enhanced. Thus, we suggest that HIV-1 virions are actively altered by the extracellular microenvironment and that NERT may play an important role in viral infection of nondividing cells.
PMCID: PMC190138  PMID: 8627755
16.  Frequent Emergence of N348I in HIV-1 Subtype C Reverse Transcriptase with Failure of Initial Therapy Reduces Susceptibility to Reverse-Transcriptase Inhibitors 
N348I emerges frequently with failure of first-line antiretroviral therapy (ART) in subtype C human immunodeficiency virus type 1 infection and affects susceptibility to nevirapine, efavirenz, etravirine, and zidovudine. This finding has implications for cross-resistance to subsequent ART regimens in resource-limited settings.
Background. It is not known how often mutations in the connection and ribonuclease H domains of reverse transcriptase (RT) emerge with failure of first-line antiretroviral therapy (ART) in subtype C human immunodeficiency virus type 1 (HIV-1) infection and how these mutations affect susceptibility to other antiretrovirals.
Methods. We compared full-length RT sequences in plasma obtained before therapy and at virologic failure of initial ART among 63 participants with subtype C HIV-1 infection enrolled in the Comprehensive International Program of Research on AIDS in South Africa (CIPRA-SA) study. Recombinant viruses containing full-length plasma-derived RT sequences from participants with N348I at virologic failure were assayed for drug susceptibility.
Results. Y181C and M184V mutations in the RT polymerase domain were associated with failure of stavudine-lamivudine-nevirapine (d4T/3TC/NVP; P < .01), and K103N, V106M, and M184V with failure of d4T/3TC/efavirenz (EFV; P < .01). N348I in the RT connection domain emerged in 45% (P = .002) and 12% (P = .06) of participants receiving failing regimens containing NVP or EFV, respectively. Longitudinal analyses revealed that nonnucleoside RT inhibitor resistance mutations in the polymerase domain generally appeared first. N348I emerged at the same time, or after, M184V. N348I in the context of polymerase domain mutations reduced susceptibility to NVP (8.9–13-fold), EFV (4–56-fold), etravirine (ETV; 1.9–4.7-fold) and decreased hypersusceptibility to zidovudine (AZT; 1.4–2.2-fold).
Conclusions. N348I emerges frequently with virologic failure of first-line ART in subtype C HIV-1 infection and reduces susceptibility to NVP, EFV, ETV, and AZT. Additional studies are warranted to characterize the effects of N348I on virologic response to second- and third-line regimens in resource-limited settings where subtype C predominates.
PMCID: PMC3491849  PMID: 22618567
17.  The triple combination of tenofovir, emtricitabine and efavirenz shows synergistic anti-HIV-1 activity in vitro: a mechanism of action study 
Retrovirology  2009;6:44.
Tenofovir disoproxil fumarate (TDF), emtricitabine (FTC), and efavirenz (EFV) are the three components of the once-daily, single tablet regimen (Atripla) for treatment of HIV-1 infection. Previous cell culture studies have demonstrated that the double combination of tenofovir (TFV), the parent drug of TDF, and FTC were additive to synergistic in their anti-HIV activity, which correlated with increased levels of intracellular phosphorylation of both compounds.
In this study, we demonstrated the combinations of TFV+FTC, TFV+EFV, FTC+EFV, and TFV+FTC+EFV synergistically inhibit HIV replication in cell culture and synergistically inhibit HIV-1 reverse transcriptase (RT) catalyzed DNA synthesis in biochemical assays. Several different methods were applied to define synergy including median-effect analysis, MacSynergy®II and quantitative isobologram analysis. We demonstrated that the enhanced formation of dead-end complexes (DEC) by HIV-1 RT and TFV-terminated DNA in the presence of FTC-triphosphate (TP) could contribute to the synergy observed for the combination of TFV+FTC, possibly through reduced terminal NRTI excision. Furthermore, we showed that EFV facilitated efficient formation of stable, DEC-like complexes by TFV- or FTC-monophosphate (MP)-terminated DNA and this can contribute to the synergistic inhibition of HIV-1 RT by TFV-diphosphate (DP)+EFV and FTC-TP+EFV combinations.
This study demonstrated a clear correlation between the synergistic antiviral activities of TFV+FTC, TFV+EFV, FTC+EFV, and TFV+FTC+EFV combinations and synergistic HIV-1 RT inhibition at the enzymatic level. We propose the molecular mechanisms for the TFV+FTC+EFV synergy to be a combination of increased levels of the active metabolites TFV-DP and FTC-TP and enhanced DEC formation by a chain-terminated DNA and HIV-1 RT in the presence of the second and the third drug in the combination. This study furthers the understanding of the longstanding observations of synergistic anti-HIV-1 effects of many NRTI+NNRTI and certain NRTI+NRTI combinations in cell culture, and provides biochemical evidence that combinations of anti-HIV agents can increase the intracellular drug efficacy, without increasing the extracellular drug concentrations.
PMCID: PMC2693498  PMID: 19439089
18.  In Vitro Microbicidal Activity of the Nonnucleoside Reverse Transcriptase Inhibitor (NNRTI) UC781 against NNRTI-Resistant Human Immunodeficiency Virus Type 1 
Journal of Virology  2006;80(9):4440-4446.
The nonnucleoside reverse transcriptase inhibitor (NNRTI) UC781 is under development as a microbicide to prevent sexual transmission of the human immunodeficiency virus type 1 (HIV-1). However, NNRTI-resistant HIV-1 is increasingly prevalent in the infected population, and one of the concerns for NNRTI-based microbicides is that they will be ineffective against drug-resistant virus and may in fact selectively transmit NNRTI-resistant virus. We evaluated the microbicidal activity of UC781 against UC781-resistant (UCR), efavirenz-resistant (EFVR), and nevirapine-resistant (NVPR) strains in a variety of microbicide-relevant tests, including inactivation of cell-free virus, inhibition of cell-to-cell HIV-1 transmission, and the ability of UC781 pretreatment to protect cells from subsequent infection in the absence of exogenous drug. UC781 was 10- to 100-fold less effective against NNRTI-resistant HIV-1 compared to wild-type (wt) virus in each of these tests, with UC781 microbicidal activity against the various virus strains being wt ≥ NVPR > UCR ≥ EFVR. Breakthrough experiments using UC781-pretreated cells and mixtures of wt and NNRTI-resistant HIV-1 showed that UC781-pretreatment selected for NNRTI-resistant HIV-1. However, the efficacy of UC781 was dose dependent, and 25 μM UC781 provided essentially equivalent microbicidal activity against NNRTI-resistant and wt virus. The amount of UC781 in topical microbicide formulations under current development is approximately 100-fold greater than this concentration, so transmission of NNRTI-resistant virus may not be an issue at these microbicide formulation levels of UC781. Nonetheless, the reduced microbicidal activity of UC781 against NNRTI-resistant HIV-1 suggests that additional antiviral agents should be included in NNRTI-based microbicide formulations.
PMCID: PMC1472006  PMID: 16611904
19.  Switch to Stribild versus continuation of NVP or RPV with FTC and TDF in virologically suppressed HIV adults: a STRATEGY-NNRTI subgroup analysis 
Journal of the International AIDS Society  2014;17(4Suppl 3):19793.
Switch to Stribild (STB) was non-inferior to continuation of a non-nucleoside reverse transcriptase inhibitor (NNRTI) with emtricitabine and tenofovir DF (FTC/TDF) at week 48 in virologically suppressed HIV adults [1]. We report the Week 48 efficacy and safety of STB versus nevirapine (NVP) or rilpivirine (RPV) with FTC/TDF in suppressed subjects.
Materials and Methods
Virologically suppressed subjects on an NNRTI with FTC/TDF regimens for ≥6 months were randomized (2:1) to switch to STB versus continue their NNRTI regimen. Eligibility criteria included no documented resistance to FTC and TDF, no history of virologic failure and eGFR ≥70 mL/min. The primary endpoint was the proportion of subjects in the modified ITT population who maintained HIV-1 RNA <50 copies(c)/mL at Week 48 by FDA snapshot algorithm (12% non-inferiority margin). Subgroup analysis by non-EFV NNRTI use (NVP [74]; RPV [19]; etravirine [3]) at screening was pre-specified.
The mITT population included 433 subjects who were randomized and treated. In the non-EFV NNRTI subgroup, 59 switched to STB; 37 continued a non-EFV NNRTI (27 NVP, 10 RPV) with FTC/TDF. At week 48, 97% STB versus 95% non-EFV NNRTI maintained HIV-1 RNA <50 c/mL. No emergent resistance was detected in either group. No difference in median increases from baseline in CD4 count at week 48 (cells/µL): 25 STB versus 55 non-EFV NNRTI (p=0.78). No discontinuation due to adverse events; no cases of proximal renal tubulopathy. As expected, there were no significant changes in the frequency of neuropsychiatric symptoms (i.e. anxiety, insomnia, dizziness, vivid dreams, weird/intense dreams, and nightmares) reported on the HIV Symptom Index at week 48 compared to baseline after switching to STB. There was a greater but non-progressive decrease from baseline in eGFR in the STB versus non-EFV NNRTI group; median changes (mL/min) at week 48: −9.1 versus −1.4. Switch to STB was associated with a higher treatment ease (convenience, flexibility, demand, lifestyle, understanding) score (range: −15 to 15) at week 4 (median: 14 vs 11; p=0.047) and week 24 (median: 14 vs 12.5; p=0.038).
In this small group of virologically suppressed subjects, switch to STB vs continuation of NVP or RPV with FTC/TDF was safe, well-tolerated, and associated with a high rate of virologic suppression at week 48. There was more treatment ease with STB use.
PMCID: PMC4225425  PMID: 25397537
20.  Outcomes for Efavirenz versus Nevirapine-Containing Regimens for Treatment of HIV-1 Infection: A Systematic Review and Meta-Analysis 
PLoS ONE  2013;8(7):e68995.
There is conflicting evidence and practice regarding the use of the non-nucleoside reverse transcriptase inhibitors (NNRTI) efavirenz (EFV) and nevirapine (NVP) in first-line antiretroviral therapy (ART).
We systematically reviewed virological outcomes in HIV-1 infected, treatment-naive patients on regimens containing EFV versus NVP from randomised trials and observational cohort studies. Data sources include PubMed, Embase, the Cochrane Central Register of Controlled Trials and conference proceedings of the International AIDS Society, Conference on Retroviruses and Opportunistic Infections, between 1996 to May 2013. Relative risks (RR) and 95% confidence intervals were synthesized using random-effects meta-analysis. Heterogeneity was assessed using the I2 statistic, and subgroup analyses performed to assess the potential influence of study design, duration of follow up, location, and tuberculosis treatment. Sensitivity analyses explored the potential influence of different dosages of NVP and different viral load thresholds.
Of 5011 citations retrieved, 38 reports of studies comprising 114 391 patients were included for review. EFV was significantly less likely than NVP to lead to virologic failure in both trials (RR 0.85 [0.73–0.99] I2 = 0%) and observational studies (RR 0.65 [0.59–0.71] I2 = 54%). EFV was more likely to achieve virologic success than NVP, though marginally significant, in both randomised controlled trials (RR 1.04 [1.00–1.08] I2 = 0%) and observational studies (RR 1.06 [1.00–1.12] I2 = 68%).
EFV-based first line ART is significantly less likely to lead to virologic failure compared to NVP-based ART. This finding supports the use of EFV as the preferred NNRTI in first-line treatment regimen for HIV treatment, particularly in resource limited settings.
PMCID: PMC3718822  PMID: 23894391
21.  Lack of association between plasma levels of non-nucleoside reverse transcriptase inhibitors & virological outcomes during rifampicin co-administration in HIV-infected TB patients 
Background & objectives:
Among patients with HIV-associated tuberculosis (TB), reduced plasma non-nucleoside reverse transcriptase inhibitors (NNRTI) concentrations during rifampicin (RMP) co-administration could lead to HIV treatment failure. This study was undertaken to examine the association between plasma nevirapine (NVP) and efavirenz (EFV) concentrations and virological outcomes in patients infected with HIV-1 and TB.
This was a nested study undertaken in a clinical trial of patients with HIV-1 and TB, randomized to two different once-daily antiretroviral treatment (ART) regimens along with anti-TB treatment (ATT). Trough concentrations of plasma NVP and EFV were estimated at months 1 (during ATT and ART) and 6 months (ART only) by HPLC. Plasma HIV-1 RNA level >400 copies/ml or death within 6 months of ART were considered as unfavourable outcomes. Genotyping of CYP2B6 516G>T polymorphism was performed.
Twenty nine per cent of patients in NVP arm had an unfavourable outcome at 6 months compared to 9 per cent in EFV arm (P<0.08). The mean NVP and EFV levels estimated at 1 and 6 months did not significantly differ between favourable and unfavourable responders. Logistic regression analysis showed CYP2B6 516G>T polymorphism significantly associated with virologic outcome in patients receiving EFV–based regimen.
Interpretation & conclusions:
Trough plasma concentrations of NVP and EFV did not show any association with response to ART in patients on ATT and once-daily ART. CYP2B6 516G>T polymorphism was associated with virologic outcome among patients on EFV.
PMCID: PMC3978988  PMID: 24521642
HIV-1 & tuberculosis; NNRTIs; rifampicin; TDM; virologic outcome
22.  Efficacy and Safety of Three Antiretroviral Regimens for Initial Treatment of HIV-1: A Randomized Clinical Trial in Diverse Multinational Settings 
PLoS Medicine  2012;9(8):e1001290.
Thomas Campbell and colleagues report findings of a randomized trial conducted in multiple countries regarding the efficacy of antiretroviral regimens with simplified dosing.
Antiretroviral regimens with simplified dosing and better safety are needed to maximize the efficiency of antiretroviral delivery in resource-limited settings. We investigated the efficacy and safety of antiretroviral regimens with once-daily compared to twice-daily dosing in diverse areas of the world.
Methods and Findings
1,571 HIV-1-infected persons (47% women) from nine countries in four continents were assigned with equal probability to open-label antiretroviral therapy with efavirenz plus lamivudine-zidovudine (EFV+3TC-ZDV), atazanavir plus didanosine-EC plus emtricitabine (ATV+DDI+FTC), or efavirenz plus emtricitabine-tenofovir-disoproxil fumarate (DF) (EFV+FTC-TDF). ATV+DDI+FTC and EFV+FTC-TDF were hypothesized to be non-inferior to EFV+3TC-ZDV if the upper one-sided 95% confidence bound for the hazard ratio (HR) was ≤1.35 when 30% of participants had treatment failure.
An independent monitoring board recommended stopping study follow-up prior to accumulation of 472 treatment failures. Comparing EFV+FTC-TDF to EFV+3TC-ZDV, during a median 184 wk of follow-up there were 95 treatment failures (18%) among 526 participants versus 98 failures among 519 participants (19%; HR 0.95, 95% CI 0.72–1.27; p = 0.74). Safety endpoints occurred in 243 (46%) participants assigned to EFV+FTC-TDF versus 313 (60%) assigned to EFV+3TC-ZDV (HR 0.64, CI 0.54–0.76; p<0.001) and there was a significant interaction between sex and regimen safety (HR 0.50, CI 0.39–0.64 for women; HR 0.79, CI 0.62–1.00 for men; p = 0.01). Comparing ATV+DDI+FTC to EFV+3TC-ZDV, during a median follow-up of 81 wk there were 108 failures (21%) among 526 participants assigned to ATV+DDI+FTC and 76 (15%) among 519 participants assigned to EFV+3TC-ZDV (HR 1.51, CI 1.12–2.04; p = 0.007).
EFV+FTC-TDF had similar high efficacy compared to EFV+3TC-ZDV in this trial population, recruited in diverse multinational settings. Superior safety, especially in HIV-1-infected women, and once-daily dosing of EFV+FTC-TDF are advantageous for use of this regimen for initial treatment of HIV-1 infection in resource-limited countries. ATV+DDI+FTC had inferior efficacy and is not recommended as an initial antiretroviral regimen.
Trial Registration NCT00084136
Please see later in the article for the Editors' Summary.
Editors' Summary
Despite the enormous gains in reducing HIV-related illness and death over the past decade, there are still considerable challenges to meeting the global goal of universal access to highly active antiretroviral treatment—a combination of effective drugs that attack the HIV virus in various ways—to everyone living with HIV/AIDS who could benefit from treatment. In recognition of the related financial, technical, and system obstacles to providing universal access to HIV treatment, in 2010 the UN agency responsible for HIV/AIDS—UNAIDS—launched an ambitious plan called Treatment 2.0, which aims to simplify the way HIV treatment is currently provided. One of the main focuses of Treatment 2.0 is to simplify drug regimes for the treatment of HIV and to make treatment regimes less toxic. In line with Treatment 2.0, the World Health Organization currently recommends that antiretroviral regimens for the initial treatment of HIV should include two nucleoside reverse transcriptase inhibitors (zidovudine or tenofovir disoproxil fumarate [DF] with lamivudine or emtricitabine) and a non-nucleoside reverse transcriptase inhibitor (efavirenz or nevirapine.)
Why Was This Study Done?
Most of the evidence about the safety and effectiveness of clinical trials come from clinical trials in high-income countries and thus is not generally representative of the majority of people with HIV. So in this study, the researchers conducted a randomized controlled trial in diverse populations in many different settings to investigate whether antiretroviral regimens administered once daily were as effective as twice-daily regimens and also whether a regimen containing the drug atazanavir administered once daily was as safe and effective as a regimen containing efavirenz—data from previous studies have suggested that atazanavir has characteristics, such as its side effect profile, which may make it more suitable for low income settings.
What Did the Researchers Do and Find?
The researchers recruited eligible patients from centers in Brazil, Haiti, India, Malawi, Peru, South Africa, Thailand, the United States, and Zimbabwe—almost half (47%) were women. Then the researchers randomly assigned participants to one of three regimens: efavirenz 600 mg daily plus co-formulated lamivudine-zidovudine 150 mg/300 mg twice daily (EFV+3TC-ZDV); or atazanavir 400 mg once daily, plus didanosine-EC 400 mg once daily, plus emtricitabine 200 mg once daily (ATV+DDI+FTC); or efavirenz 600 mg once daily plus coformulated emtricitabine-tenofovir-DF 200 mg/300 mg once daily (EFV+FTC-TDF). During the study period ATV+DDI+FTC was found to be inferior to EFV+3TC-ZDV, so the Multinational Data Safety Monitoring Board ordered this arm of the trial to stop. Then a year later, due to the low number of treatment failures (deaths, severe HIV disease, or serious opportunistic infections) in the remaining two arms, the board advised the trial to stop early. So the researchers analyzed the data obtained up to this point and pooled the results from all of the centers.
The researchers found that during an average of 184 weeks of follow-up, there were 95 treatment failures (18%) among 526 participants taking EFV+FTC-TDF compared to 98 failures among 519 participants taking EFV+3TC-ZDV. During an average 81 weeks follow-up, there were 108 failures (21%) among 526 participants assigned to ATV+DDI+FTC and 76 (15%) among 519 participants assigned to EFV+3TC-ZDV. As for safety, 243 (46%) participants assigned to EFV+FTC-TDF reached a safety endpoint (grade 3 disease, abnormal lab measurement, or the need to change drug) compared to 313 (60%) in the EFV+3TC-ZDV group. Importantly, the researchers found that there was greater risk of safety events for women assigned to EFV+3TC-ZDV and also that the atazanavir-based regimen had a higher relative efficacy in women compared to men.
What Do These Findings Mean?
These findings suggest that in diverse populations, EFV+FTC-TDF is as effective as EFV+3TC-ZDV but importantly, the once-daily dosing of EFV+FTC-TDF makes this regimen useful for the initial treatment of HIV, especially in low-income countries. Therefore, as per the guidance in Treatment 2.0, EFV+FTC-TDF in a single combination tablet that can be taken once a day is an attractive option. These findings also indicate that as ATV+DDI+FTC was found to be inferior to the other regimens, this combination should not be used in the initial treatment of HIV. These findings also add to the evidence that antiretroviral efficacy and safety can differ between women and men and support further development of sex-specific recommendations for antiretroviral regimen options.
Additional Information
Please access these Web sites via the online version of this summary at
The UNAIDS website has more information about Treatment 2.0; and the WHO website provides technical information
For an introduction to the treatment of HIV/AIDS see; the AVERT site also has personal stories from women living with HIV/AIDS
AIDSmap provides information for individuals and communities affected by HIV/AIDS
The ACTG website provides information about research to improve treatment of HIV and related complications
PMCID: PMC3419182  PMID: 22936892
23.  Nevirapine plus efavirenz plus didanosine: a simple, safe, and effective once-daily regimen for patients with HIV infection. 
Conventional highly active antiretroviral therapy (HAART) regimens used to treat human immunodeficiency virus (HIV) infection typically use nucleoside reverse transcriptase inhibitors (NRTIs) and either a protease inhibitor (PI) or a non-nucleoside reverse transcriptase inhibitor (NNRTI). Because PI-based regimens are associated with significant long-term toxicity and adherence difficulty, there is a need for novel regimens that maximize combination treatment options. This 12-month, observational, cohort study evaluated the efficacy, safety, and tolerability of a novel three-drug HAART regimen. Drug treatment consisted of nevirapine (NVP), efavirenz (EFV), and didanosine (ddl). Twenty-six treatment-naive and -experienced HIV-1+ men and women were included in the study. Assessment consisted of CD4+ cell count, plasma HIV-1 RNA load, and adverse effects of study medications. After one year of therapy, 11/12 treatment-naive subjects (92%) and 8/9 treatment-experienced subjects (89%) had viral loads < 400 copies/mL. Both groups also had an excellent immune response. At one year, there was a mean increase of 438 CD4+ cells/mm3 among treatment-naive subjects and 367 cells/mm3 among treatment-experienced subjects. Treatment-limiting adverse effects occurred in 3/15 treatment-naive (20%) and 2/11 treatment-experienced (18%) subjects. These preliminary data suggest that the combination of NVP, EFV, and ddl is simple, safe, and effective.
PMCID: PMC2594848  PMID: 14717471
24.  NNRTI pharmacokinetics in a large unselected cohort of HIV-infected women 
Small intensive pharmacokinetic (PK) studies of medications in early-phase trials cannot identify the range of factors that influence drug exposure in heterogeneous populations. We performed PK studies in large numbers of HIV-infected women on nonnucleoside-reverse-transcriptase-inhibitors (NNRTIs) under conditions of actual use to assess patient characteristics that influence exposure and evaluated the relationship between exposure and response.
225 women on NNRTI-based antiretroviral regimens from the Women’s Interagency HIV Study (WIHS) were enrolled into 12 or 24-hour PK studies. Extensive demographic, laboratory and medication covariate data was collected before and during the visit to be used in multivariate models. Total NNRTI drug exposure was estimated by area-under-the-concentration-time curves (AUC).
Hepatic inflammation and renal insufficiency were independently associated with increased nevirapine (NVP) exposure in multivariate analyses; crack cocaine, high fat diets, and amenorrhea were associated with decreased levels (n=106). Higher efavirenz (EFV) exposure was seen with increased transaminase, albumin levels, and orange juice consumption; tenofovir use, increased weight, being African-American and amenorrhea were associated with decreased exposure (n=119). With every 10-fold increase in NVP or EFV exposure, participants were 3.3 and 3.6 times as likely to exhibit virologic suppression, respectively. Patients with higher drug exposure were also more likely to report side effects on therapy.
Our study identifies and quantitates previously unrecognized factors modifying NNRTI exposure in the “real-world” setting. Comprehensive PK studies in representative populations are feasible and may ultimatley lead to dose optimization strategies in patients at risk for failure or adverse events.
PMCID: PMC2700138  PMID: 19408353
HIV; antiretrovirals; nevirapine; efavirenz; pharmacokinetics; drug exposure; women
25.  Anti-Human Immunodeficiency Virus Type 1 Activity of the Nonnucleoside Reverse Transcriptase Inhibitor GW678248 in Combination with Other Antiretrovirals against Clinical Isolate Viruses and In Vitro Selection for Resistance 
Antimicrobial Agents and Chemotherapy  2005;49(11):4465-4473.
GW678248, a novel nonnucleoside reverse transcriptase inhibitor, has been evaluated for anti-human immunodeficiency virus activity in a variety of in vitro assays against laboratory strains and clinical isolates. When GW678248 was tested in combination with approved drugs in the nucleoside and nucleotide reverse transcriptase inhibitor classes or the protease inhibitor class, the antiviral activities were either synergistic or additive. When GW678248 was tested in combination with approved drugs in the nonnucleoside reverse transcriptase inhibitor class, the antiviral activities were either additive or slightly antagonistic. Clinical isolates from antiretroviral drug-experienced patients were selected for evaluation of sensitivity to GW678248 in a recombinant virus assay. Efavirenz (EFV) and nevirapine (NVP) had ≥10-fold increases in their 50% inhibitory concentrations (IC50s) for 85% and 98% of the 55 selected isolates, respectively, whereas GW678248 had a ≥10-fold increase in the IC50 for only 17% of these isolates. Thus, 81 to 83% of the EFV- and/or NVP-resistant viruses from this data set were susceptible to GW678248. Virus populations resistant to GW678248 were selected by in vitro dose-escalating serial passage. Resistant progeny viruses recovered after eight passages had amino acid substitutions V106I, E138K, and P236L in the reverse transcriptase-coding region in one passage series and amino acid substitutions K102E, V106A, and P236L in a second passage series.
PMCID: PMC1280120  PMID: 16251284

Results 1-25 (1059953)