Removal of antiretroviral drugs from wastewater using activated macadamia nutshells: Adsorption kinetics, adsorption isotherms, and thermodynamic studies

Antiretroviral drugs (ARVDs) have been extensively employed in health care to improve the quality of life and lifecycle longevity. However, overuse and improper disposal of ARVDs have been recognized as an emerging concern whereby wastewater treatment major recipients. Therefore, in this work, the activated macadamia nutshells (MCNs) were explored as low-cost adsorbents for the removal of ARVDs in wastewater samples. Fourier transform infrared spectroscopy (FTIR), Scanning Electron microscopy (SEM), Brunauer-Emmet-Teller (BET), and Powder X-ray diffraction (PXRD). The highest removal efficiency (R.E) was above 86% for the selected analytes nevirapine, abacavir, and efavirenz. The maximum adsorption capacity of the functionalized MCN adsorbent was 10.79, 27.44, and 38.17 mg/g for nevirapine, abacavir, and efavirenz for HCl-modified adsorbent. In contrast, NaOH modified had adsorption capacities of 13.67, 14.25, and 20.79 mg/g. The FTIR showed distinct functional groups OH and CO, which facilitate the removal of selected ARVDs. From studying kinetics parameters, the pseudo-second-order (R2 = 0.990-0.996) was more dominant than the pseudo-first-order (R2 = 0.872-0.994). The experimental data was most fitted in the Freundlich model with (R2 close to 1). The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic. The study indicated that MCNs are an eco-friendly, low-cost, and effective adsorbent for the removal of nevirapine, abacavir, and efavirenz. PRACTITIONER POINTS: Modification macadamia nutshell with HCl and NaOH improved physio-chemical properties that yielded high removal efficiency compared with raw macadamia nutshells. Modification of macadamia by HCl showed high removal efficiency, which could be attributed to high interaction such as H-bonding that improves adsorption. The macadamia nutshell as an adsorbent showed so much robustness with regeneration studies yielding to about 69.64% of selected compounds.

Potential Involvement of Sulfotransferase in the Mechanism of Lamotrigine-induced Skin Rash

The mechanism of drug-induced skin rash is not well understood. Circumstantial evidence suggests that the covalent binding of a reactive metabolite is involved in the mechanism of most idiosyncratic drug reactions. However, there is a limited quantity of drug metabolizing enzymes in the skin, except for sulfotransferases. It is possible that some drugs are metabolized to reactive sulfate metabolites that are responsible for skin rashes. For example, nevirapine-induced skin rash involves metabolism of nevirapine to 12-hydroxy-nevirapine, which is further metabolized by sulfotransferase in the skin to a reactive benzylic sulfate that covalently binds to proteins. The working hypothesis is that lamotrigine, valdecoxib, and sertraline skin rashes involve the formation of reactive sulfate in the skin. Lamotrigine-N-oxide, hydroxy-valdecoxib, and hydroxy-sertraline were tested as substrates with known human sulfotransferases. Hydroxy-valdecoxib and the benzylic alcohol metabolite of sertraline were not substrates for human sulfotransferases. Therefore, this pathway is presumably not involved in the mechanism by which they cause skin rashes. In contrast, lamotrigine-N-oxide is a substrate for several human sulfotransferases and the sulfate is chemically reactive. Furthermore, lamotrigine-N-sulfate not only alkylates proteins as we described previously but also forms the sulfate of tyrosine, suggesting another possible mechanism for protein modification. This study has further added to the understanding of the potential of the sulfotransferase pathways and protein sulfation to play a role in drug-induced skin rash.

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

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

Associations of modern initial antiretroviral therapy regimens with all-cause mortality in people living with HIV in resource-limited settings: a retrospective multicenter cohort study in China

Despite the proven virological advantages, there remains some controversy regarding whether first-line integrase strand transfer inhibitors (INSTIs)-based antiretroviral therapy (ART) contributes to reducing mortality of people living with HIV (PLHIV) in clinical practice. Here we report a retrospective study comparing all-cause mortality among PLHIV in China who were on different initial ART regimens (nevirapine, efavirenz, dolutegravir, lopinavir, and others [including darunavir, raltegravie, elvitegravir and rilpivirine]) between 2017 and 2019. A total of 41,018 individuals were included across China, representing 21.3% of newly reported HIV/AIDS cases collectively in the country during this period. Only the differences in all-cause mortality of PLHIV between the efavirenz group and the nevirapine group, the dolutegravir group and the nevirapine group, and the lopinavir group and the nevirapine group, were observed in China. After stratifying the cause of mortality, we found that the differences in mortality between initial ART regimens were mainly observed in AIDS-related mortality.

Case study on antiretroviral drugs uptake from soil irrigated with contaminated water: Bio-accumulation and bio-translocation to roots, stem, leaves, and fruits

This study aimed to evaluate the potential of uptake of the commonly used antiretroviral drugs (ARVDs) in South Africa (abacavir, nevirapine, and efavirenz) by vegetable plants (beetroot, spinach, and tomato) from contaminated soil culture. The study results showed that all the studied vegetables have the potential to take up abacavir, nevirapine, and efavirenz from contaminated soil, be absorbed by the root, and translocate them to the aerial part of the plants. The total percentage of ARVDs found in the individual plant was mainly attributed to abacavir which contributed 53% in beetroot and 48% in spinach, while efavirenz (42%) was the main contributor in tomato. Abacavir was found at high concentrations to a maximum of 40.21 μg/kg in the spinach root, 18.43 μg/kg in the spinach stem, and 6.77 μg/kg in the spinach soil, while efavirenz was the highest concentrations, up to 35.44 μg/kg in tomato leaves and 8.86 μg/kg in tomato fruits. Spinach roots accumulated more ARVDs than beetroot and tomato however, the concentrations were not statistically different. Hydrophobicity was the main effect on the linearity, accumulation, and translocation of ARVDs. This study advances knowledge on the fate of ARVDs in agroecosystems, particularly in plant root - ARVD interaction and the resulting potentially toxic effects on plants. These results suggest that the quality of water used for crop irrigation needs to be assessed prior to irrigation to avoid vegetable plant pollution as contaminated water results in the contaminants uptake by plants. This may lead to the transfer of pollutants to the edible crops parts of and thus be unintentionally consumed by humans. More studies need to be continuously conducted to evaluate ARVDs bioaccumulation and their mechanism of uptake by other vegetables. The use of the pot-plant system can be recommended because it closely relates to the agricultural world.

Maraviroc Population Pharmacokinetics Within the First 6 Weeks of Life

BACKGROUND

Treatment and prophylaxis options for neonatal HIV are limited. This study aimed to develop a population pharmacokinetic model to characterize the disposition of maraviroc in neonates to inform dosing regimens and expand available options.

METHODS

Using maraviroc concentrations from neonates who received either a single dose or multiple doses of 8 mg/kg of maraviroc in the first 6 weeks of life, a population pharmacokinetic model was developed to determine the effects of age, sex, maternal efavirenz exposure and concomitant ARV therapy on maraviroc disposition. The final model was used in Monte Carlo simulations to generate expected exposures with recommended dosing regimens.

RESULTS

A total of 396 maraviroc concentrations, collected in the first 4 days of life, at 1 week, at 4 weeks and at 6 weeks, from 44 neonates were included in the analysis. After allometrically scaling for weight, age less than 4 days was associated with a 44% decreased apparent clearance compared with participants 7 days to 6 weeks of life. There were no differences identified in apparent clearance or volume of distribution from ages 7 days to 6 weeks, sex, maternal efavirenz exposure or concomitant nevirapine therapy. Monte Carlo simulations with FDA-approved weight band dosing resulted in the majority of simulated patients (84.3%) achieving an average concentration of ≥75 ng/mL.

CONCLUSIONS

While maraviroc apparent clearance is decreased in the first few days of life, the current FDA-approved maraviroc weight band dosing provides maraviroc exposures for neonates in the first 6 weeks of life, which were consistent with adult maraviroc exposure range. Maraviroc provides another antiretroviral treatment option for very young infants.

Development and application of a membrane assisted solvent extraction-molecularly imprinted polymer based passive sampler for monitoring of selected pharmaceuticals in surface water

In this work, we demonstrate the development, evaluation and pre-liminary application of a novel passive sampler for monitoring of selected pharmaceuticals in environmental waters. The samplers were calibrated in laboratory-based experiments to obtain sampling rates (Rs) for carbamazepine, methocarbamol, etilefrine, venlafaxine and nevirapine. Passive sampling was based on the diffusion of the target pharmaceuticals from surface water through a membrane bag which housed an ionic liquid as a green receiving solvent and a molecularly imprinted polymer. Effects of biofouling, deployment time and solvent type for the receiver phase were optimized for selective uptake of analytes in surface water. Notably, there was a decrease in the uptake of selected pharmaceuticals and consequently a decrease in their sampling rates in the presence of biofouling. The optimum matrix-matched sampling rates ranged from 0.0007 - 0.0018 L d^-1 whilst the method detection and quantification limits ranged from 2.45 - 3.26 ng L^-1 and 8.06 - 10.81 ng L^-1, respectively. The optimized passive sampler was deployed in a dam situated in the heart of a typical highly populated township in the Gauteng Province of South Africa. Only etilefrine and methocarbamol were detected and quantified at maximum time weighted average concentrations of 12.88 and 72.29 ng L^-1, respectively.

Design, Synthesis and Structure-Activity Relationships of Phenylalanine-Containing Peptidomimetics as Novel HIV-1 Capsid Binders Based on Ugi Four-Component Reaction

As a key structural protein, HIV capsid (CA) protein plays multiple roles in the HIV life cycle, and is considered a promising target for anti-HIV treatment. Based on the structural information of CA modulator PF-74 bound to HIV-1 CA hexamer, 18 novel phenylalanine derivatives were synthesized via the Ugi four-component reaction. In vitro anti-HIV activity assays showed that most compounds exhibited low-micromolar-inhibitory potency against HIV. Among them, compound I-19 exhibited the best anti-HIV-1 activity (EC50 = 2.53 ± 0.84 μM, CC50 = 107.61 ± 27.43 μM). In addition, I-14 displayed excellent HIV-2 inhibitory activity (EC50 = 2.30 ± 0.11 μM, CC50 > 189.32 μM) with relatively low cytotoxicity, being more potent than that of the approved drug nevirapine (EC50 > 15.02 μM, CC50 > 15.2 μM). Additionally, surface plasmon resonance (SPR) binding assays demonstrated direct binding to the HIV CA protein. Moreover, molecular docking and molecular dynamics simulations provided additional information on the binding mode of I-19 to HIV-1 CA. In summary, we further explored the structure—activity relationships (SARs) and selectivity of anti-HIV-1/HIV-2 of PF-74 derivatives, which is conducive to discovering efficient anti-HIV drugs.

A sensitive sensor based on molecularly imprinted polypyrrole on reduced graphene oxide modified glassy carbon electrode for nevirapine analysis

A molecularly imprinted polymer (MIP) sensor was offered for nevirapine (NVP) analysis based on the electropolymerization of pyrrole (Py) on electrochemically reduced graphene oxide (ErGO) immobilized on a glassy carbon electrode (GCE). Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and atomic force microscope (AFM) were applied to characterize the proposed sensor (MIP/ErGO/GCE). The electrochemical operation of this sensor for NVP analysis was tested using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) methods in an alkaline medium. The prepared MIP/ErGO/GCE exhibited better analytical performance than other modified electrodes toward NVP detection. The offered sensor depicted a linearity range between 0.005 µM and 400 µM with a limit of detection (LOD) of 2 nM under optimal conditions. Notably, the offered sensor illustrated excellent selectivity, good reproducibility, acceptable repeatability, and reliable long-term performance. These experiments depicted the constructed sensor as a favorable and good sensing element towards NVP monitoring in pharmaceutical and serum samples.

The chlorination behaviour and environmental fate of the antiretroviral drug nevirapine in South African surface water

The wastewater treatment process, besides discharging pharmaceuticals into the environment, has been found to result in the formation of a variety of undescribed compounds. Here we investigate the laboratory scale chlorination of the commonly used anti-HIV drug Nevirapine, characterise its disinfection transformation products (DTPs), and using liquid chromatography with high resolution mass spectrometry, screen environmental surface water for these DTPs. Chlorination of Nevirapine was scaled up, fractioned by preparative chromatography and the fractions were tested in vitro for toxicity and anti-HIV activity. Nevirapine was found to be resistant to degradation at relevant chlorination levels, which may partially explain its ubiquitous presence in South African surface water. During simulated chlorination, a variety of DTPs with varying properties were formed, some of which were detected in the environment, close to wastewater treatment plants. Interestingly, some of these compounds, although not as toxic as Nevirapine, retained antiviral activity. Further purification and synthesis is required to fully characterise these novel molecules.

[Analysis on HIV suppression effect after initiating antiretroviral treatment and related factors among AIDS patients in Henan province during 2008 and 2013]

OBJECTIVE

To compare the HIV suppression rate after initiating antiretroviral treatment(ART) among AIDS patients at different immunological levels and to analyze the related factors.

METHODS

Data on AIDS patients initially starting antiretroviral therapy during 2008 and 2013 were collected from Chinese HIV/AIDS integrated control system. All the participants were divided into early treatment group(baseline CD4(+)T cell counts between 351/µl and 500/µl) and conventional treatment group(baseline CD4(+)T cell counts ≤ 350/µl). The rates of comprehensive virologic suppression at different time nodes after the initiation of ART were analyzed accordingly. Unconditional logistic regression model was adopted to examine the factors associated with the failure of viral suppression after 6 months after initiation of ART.

RESULTS

A total of 16 103 cases were selected, among which, 1 581 cases were early treatment group, and 14 522 cases were conventional treatment group. A total of 9 428 cases were males, 6 675 cases were females, and the sex ratio was 1.41: 1. The age was 47.2 ± 11.7, and 71.55% (11 522/16 103) of cases were married or cohabiting, 57.22% (9 214/16 103) were transmitted by blood. 81.26% (13 086/16 103) were cures in the township or village treatment institution, and 77.17% (12 426/16 103) received the ART regimen as Stavudine(D4T) or Zidovudine(AZT)+Lamivudine(3TC)+Nevirapine(NVP) or Efevirenz(EFV). After 0.5, 1, 2, 3, 4, 5 and 6 years after the initiation of ART, the rates of virologic suppression in the conventional treatment cohort were 72.6% (3 008/4 144), 73.9% (4 758/6 443), 74.1% (3 641/4 915), 74.9% (2 819/3 766), 76.1% (1 729/2 272) and 78.2% (492/629), respectively. While the rates of viral suppression in the early treatment cohort at the same time nodes were 65.5% (315/481), 65.4% (448/685), 68.8% (223/324), 66.0% (155/235), 71.4% (110/154) and 61% (30/49), respectively, and the differences between the two groups were significant (P < 0.05) except at the fourth year. Non-conditional logistic regression analysis showed that in the conventional treatment group, factors associated with low HIV suppression rate were male (OR = 1.23, 95%CI:1.07-1.42) , longer time interval from confirmed HIV infection to received ART (OR = 1.26, 95%CI:1.16-1.36) , using D4T/AZT+ DDI +NVP/EFV as initial treatment regimen (OR = 3.00, 95%CI:2.26-3.98) and nearly missing doses for 7 days at treatment of six months (OR = 1.97, 95%CI:1.22-3.18) and factors associated with high HIV suppression rate were infected through homosexual transmission route (OR = 0.57, 95%CI:0.35-0.90) and treated in the county level medical institution or above (OR = 0.61, 95%CI:0.50-0.75) . Among early treatment group, cases who received treatment at county level medical institution or above had high HIV suppression rate (OR = 0.43, 95%CI:0.23-0.80) and objects with longer time interval from confirmed HIV infection to receive ART had low HIV suppression rate (OR = 1.43, 95%CI:1.09-1.88).

CONCLUSION

The viral suppression efficacy among AIDS patients with different baseline immunologic levels after treatment was similarly satisfactory. AIDS cases who received ART at county level medical institution or above had better viral suppression effect and patients with longer time interval from confirmation to treatment had poor HIV suppression effect.

In vitro and ex vivo inhibition of human telomerase by anti-HIV nucleoside reverse transcriptase inhibitors (NRTIs) but not by non-NRTIs

Telomerase is a specialized reverse transcriptase responsible for the de novo synthesis of telomeric DNA repeats. In addition to its established reverse transcriptase and terminal transferase activities, recent reports have revealed unexpected cellular activities of telomerase, including RNA-dependent RNA polymerization. This telomerase characteristic, distinct from other reverse transcriptases, indicates that clinically relevant reverse transcriptase inhibitors might have unexpected telomerase inhibition profiles. This is particularly important for the newer generation of RT inhibitors designed for anti-HIV therapy, which have reported higher safety margins than older agents. Using an in vitro primer extension assay, we tested the effects of clinically relevant HIV reverse transcriptase inhibitors on cellular telomerase activity. We observed that all commonly used nucleoside reverse transcriptase inhibitors (NRTIs), including zidovudine, stavudine, tenofovir, didanosine and abacavir, inhibit telomerase effectively in vitro. Truncated telomere synthesis was consistent with the expected mode of inhibition by all tested NRTIs. Through dose-response experiments, we established relative inhibitory potencies of NRTIs on in vitro telomerase activity as compared to the inhibitory potencies of the corresponding dideoxynucleotide triphosphates. In contrast to NRTIs, the non-nucleoside reverse transcriptase inhibitors (NNRTIs) nevirapine and efavirenz did not inhibit the primer extension activity of telomerase, even at millimolar concentrations. Long-term, continuous treatment of human HT29 cells with select NRTIs resulted in an accelerated loss of telomere repeats. All tested NRTIs exhibited the same rank order of inhibitory potencies on telomerase and HIV RT, which, according to published data, were orders-of-magnitude more sensitive than other DNA polymerases, including the susceptible mitochondria-specific DNA polymerase gamma. We concluded that telomerase activity could be inhibited by common NRTIs, including currently recommended RTI agents tenofovir and abacavir, which warrants large-scale clinical and epidemiological investigation of the off-target effects of long-term highly active antiretroviral therapy (HAART) with these agents.

Comparison of HPLC & spectrophotometric methods for estimation of antiretroviral drug content in pharmaceutical products

BACKGROUND & OBJECTIVES

Simple and reliable methods to estimate drugs in pharmaceutical products are needed. In most cases, antiretroviral drug estimations are performed using a HPLC method, requiring expensive equipment and trained technicians. A relatively simple and accurate method to estimate antiretroviral drugs in pharmaceutical preparations is by spectrophotometric method, which is cheap and simple to use as compared to HPLC. We undertook this study to standardise methods for estimation of nevirapine (NVP), lamivudine (3TC) and stavudine (d4T) in single tablets/capsules by HPLC and spectrophotometry and to compare the content of these drugs determined by both these methods.

METHODS

Twenty tablets/capsules of NVP, 3TC and d4T each were analysed for their drug content by HPLC and spectrophotometric methods. Suitably diluted drug solutions were run on HPLC fitted with a C18 column using UV detection at ambient temperature. The absorbance of the diluted drug solutions were read in a spectrophotometer at 300, 285 and 270 nm for NVP, 3TC and d4T respectively. Pure powders of the drugs were used to prepare calibration standards of known drug concentrations, which was set up with each assay.

RESULTS

The inter-day variation (%) of standards for NVP, 3TC and d4T ranged from 2.5 to 6.7, 2.1 to 7.7 and 6.2 to 7.7, respectively by HPLC. The corresponding values by spectrophotometric method were 2.7 to 4.7, 4.2 to 7.2 and 3.8 to 6.0. The per cent variation between the HPLC and spectrophotometric methods ranged from 0.45 to 4.49 per cent, 0 to 4.98 per cent and 0.35 to 8.73 per cent for NVP, 3TC and d4T,respectively.

CONCLUSIONS

The contents of NVP, 3TC and d4T in the tablets estimated by HPLC and spectrophotometric methods were similar, and the variation in the amount of these drugs estimated by HPLC and spectrophotometric methods was below 10 per cent. This suggests that the spectrophotometric method is as accurate as the HPLC method for estimation of NVP, 3TC and d4T in tablet/capsule. Hence laboratories that do not have HPLC equipment can also undertake these drug estimations using spectrophotometer.

Evaluation of nevirapine-switch strategies for HIV treatment

Despite the benefits of protease inhibitor (PI)-based HIV treatment, issues of tolerability, dosing frequency, pill count and long-term metabolic complications necessitate evaluation of alternate treatment strategies. The weight of evidence demonstrates that a switch from a PI-based regimen to one containing nevirapine can be accomplished safely while maintaining virological suppression. There is no immunological cost. There is probably an overall benefit in terms of the metabolic milieu.

Studies of nonnucleoside HIV-1 reverse transcriptase inhibitors. Part 1: Design and synthesis of thiazolidenebenzenesulfonamides

A random high-throughput screening (HTS) program to discover novel nonnucleoside reverse transcriptase inhibitors (NNRTIs) has been carried out with MT-4 cells against a nevirapine-resistant virus, HIV-1(IIIB-R). The primary hit, a thiazolidenebenzenesulfonamide derivative, possessed good activity. A systematic modification program examining various substituents at the 3-, 4-, and 5-positions on the thiazole ring afforded compounds with enhanced anti-HIV-1 and reverse transcriptase (RT) inhibitory activities. These results confirm the important role of the substituents at these positions and the thiazolidenebenzenesulfonamide motif as a valuable lead series for the next generation NNRTIs.

Overshoot of HIV-1 viraemia after early discontinuation of antiretroviral treatment

OBJECTIVE

To determine whether, as predicted by predator-prey dynamics, early withdrawal of antiretroviral therapy, i.e. when the number of CD4+ lymphocytes is still elevated, results in an overshoot of HIV-1 viraemia due to infection of increased numbers of available target cells at that time.

DESIGN AND METHODS

Five HIV-1-infected individuals were identified who discontinued antiretroviral therapy for various reasons after 8-19 days, and from whom stored serum samples obtained before, during, and shortly after treatment were available for measurement of HIV-1 RNA load. A mathematical model was designed to assess whether increased target cell availability could quantitatively explain the clinical observations.

RESULTS

After therapy withdrawal, increases in the HIV-1 RNA load to levels exceeding pretreatment values by log10 0.6-1.5 copies/ml were observed after 2-17 days in all four of the individuals who had treatment-induced increases in CD4+ cell counts at the time of therapy withdrawal. Increases in viraemia were maximal within a few days, and subsequently seemed to wane until the pretreatment equilibrium between virus and its target cells was attained. Mathematical modelling confirms that these transient increases in viraemia can be explained by increased availability of target cells at the time of therapy withdrawal.

CONCLUSIONS

Transient rises in HIV-1 viraemia do occur following early therapy withdrawal. These rises especially warrant consideration in short-term antiretroviral regimens for prevention of mother-to-child transmission, as are being studied in developing countries, since they could result in an increased transmission risk during the post-partum period through breast-feeding. This possibility needs to be investigated urgently.

Novel non-nucleoside inhibitors of human immunodeficiency virus type 1 reverse transcriptase. 6. 2-Indol-3-yl- and 2-azaindol-3-yl-dipyridodiazepinones

Modification of the non-nucleoside inhibitor of HIV-1 reverse transcriptase nevirapine (Viramune) by incorporation of a 2-indolyl substituent confers activity against several mutant forms of the enzyme.

Sequence and drug susceptibility of subtype C reverse transcriptase from human immunodeficiency virus type 1 seroconverters in Zimbabwe

Naturally occurring human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) variability has implications for the success of antiretroviral therapy. We determined the sequence of the polymerase-coding region of RT from virus isolates from 12 Zimbabwean individuals recently infected with HIV-1. The 12 RT sequences differed from the consensus B RT sequence at 10.5% of nucleotides and 5.8% of amino acids. Susceptibility testing of five isolates to zidovudine, didanosine, lamivudine, and nevirapine demonstrated susceptibilities similar to those of wild-type subtype B isolates. Phylogenetic analysis of 40 HIV-1 RT sequences, including the 12 Zimbabwean subtype C sequences, 11 subtype B sequences, and the 17 remaining published non-subtype B sequences showed sufficient intrasubtype RT sequence variation to differentiate subtype A, B, C, and D isolates. Five recently reported subtype C RT sequences from India grouped with the Zimbabwean subtype C sequences but had significantly less intraisolate sequence variation. Both intra- and intersubtype RT comparisons were notable for extraordinarily high ratios of synonymous to nonsynonymous differences. Although substitutions in the HIV-1 RT gene are limited by functional constraints, variation between RT sequences demonstrates phylogenetic relationships that parallel env and gag gene variation.

Monitoring plasma HIV-1 RNA levels in addition to CD4+ lymphocyte count improves assessment of antiretroviral therapeutic response. ACTG 241 Protocol Virology Substudy Team

BACKGROUND

CD4+ lymphocyte counts and plasma HIV-1 RNA levels predict progression of HIV-related disease, but the relative importance of these and other virological factors in defining response to antiretroviral therapy is not yet clear.

OBJECTIVE

To determine the short-term variability of plasma HIV-1 RNA level during stable therapy; the relative importance of pretreatment values and early changes in CD4+ count, HIV-1 RNA levels, and infectious HIV-1 titers in mononuclear cells of peripheral blood and pretreatment syncytium-inducing phenotype of an HIV-1 isolate for prediction of disease progression and decline in CD4+ counts during therapy.

DESIGN

Data were collected prospectively in a randomized, clinical trial comparing two combination regimens (ACTG [AIDS Clinical Trials Group] Protocol 241) and pooled across treatments.

SETTING

8 AIDS Clinical Trials Units.

PATIENTS

198 adults with HIV-1 infection and no more than 350 CD4+ lymphocytes/mm3 who had received at least 6 months of nucleoside therapy.

INTERVENTIONS

All patients received zidovudine and didanosine; 100 received nevirapine and 98 received placebo.

MEASUREMENTS

CD4+ lymphocyte counts, plasma HIV-1 RNA levels, and infectious HIV-1 titers in cells were measured before and 8 and 48 weeks after study treatment. Assay for the syncytium-inducing viral phenotype was done at baseline. Progression was defined as occurrence of opportunistic infection, malignancy, or death during the 48 weeks after treatment began.

RESULTS

The difference between two measurements of HIV-1 RNA levels at baseline was within +/-0.39 log10 copies/mL (2.5-fold) for 90% of 167 patients receiving stable therapy. In a multivariate model, risk for disease progression was reduced by 56% (95% CI, 8% to 79% [P = 0.028]) for every 10-fold lower HIV-1 RNA level at baseline, by 52% (CI, 6% increase to 79% reduction [P = 0.071]) for every 10-fold reduction in HIV-1 RNA level at 8 weeks after treatment initiation, and by 67% (CI, 42% to 81% [P < 0.001]) for every 2-fold higher CD4+ count at baseline. These risk factors and syncytium-inducing viral phenotype at baseline, but not infectious HIV-1 titers in circulating cells, were associated with change in CD4+ counts over 48 weeks.

CONCLUSIONS

For an individual patient, a change in plasma HIV-1 RNA level of 2.5-fold or more probably indicates a true biological change. Monitoring HIV-1 RNA levels and CD4+ lymphocytes before a change in antiretroviral treatment and monitoring HIV-1 RNA levels shortly thereafter improves prediction of disease progression and decline in CD4+ counts for 1 year compared with monitoring CD4+ counts of HIV-1 RNA levels alone. Additional monitoring of infectious HIV-1 titers in mononuclear cells of peripheral blood is not useful.

Sydney Primary HIV Infection Study Group

Human immunodeficiency virus type 1 (HIV-1) resistant to the nonnucleoside reverse transcriptase inhibitor nevirapine and to the nucleoside analogue zidovudine was transmitted from a homosexual man to his sex partner. The virus source patient had commenced combination zidovudine and nevirapine therapy 2.5 years prior to his partner's primary HIV infection. He received both therapies for 7 months, then discontinued nevirapine treatment, continuing to receive zidovudine monotherapy for a further 16 months. He had ceased zidovudine therapy 6 months before the time of his partner's seroconversion. Analysis of major and minor isolates obtained from both patients soon after onset of the recipient's primary HIV infection illness confirmed that an HIV-1 variant mutant at codons 70, 98, and 181 of the viral reverse transcriptase was transmitted. This is the first documented case of transmission of HIV-1 resistant to two antiretroviral compounds.

Prophylaxis against HIV-1 infection in chimpanzees by nevirapine, a nonnucleoside inhibitor of reverse transcriptase

Chimpanzees were challenged with HIV-1IIIB while receiving a short regimen of nevirapine (Viramune), a nonnucleoside inhibitor of HIV-1 reverse transcriptase. The untreated, control chimpanzee developed an infection characterized by seroconversion, viremia in peripheral blood mononuclear cells (PBMCs), and plasma positive for viral RNA. In contrast, the three nevirapine-treated chimpanzees remained negative for all viral markers with the exception of nested polymerase chain reaction (PCR) analysis of PBMCs for viral DNA. Although PBMCs from the three nevirapine-treated chimpanzees tested intermittently positive for viral DNA, this PCR signal disappeared and remained negative for the final five months of the study. These data indicate that orally administered nevirapine provided protection from HIV-1 infection in the chimpanzee model.

Combination treatment with zidovudine, didanosine, and nevirapine in infants with human immunodeficiency virus type 1 infection

BACKGROUND

In infants and children with maternally acquired human immunodeficiency virus type 1 (HIV-1) infection, treatment with a single antiretroviral agent has limited efficacy. We evaluated the safety and efficacy of a three-drug regimen in a small group of maternally infected infants.

METHODS

Zidovudine, didanosine, and nevirapine were administered in combination orally to eight infants 2 to 16 months of age. The efficacy of antiretroviral treatment was evaluated by serial measurements of plasma HIV-1 RNA, quantitative plasma cultures, and quantitative cultures of peripheral-blood mononuclear cells.

RESULTS

The three-drug regimen was well tolerated, without clinically important adverse events. Within four weeks, there were reductions in plasma levels of HIV-1 RNA of at least 96 percent (1.5 log) in seven of the eight study patients. Over the 6-month study period, replication of HIV-1 was controlled in two infants who began therapy at 2 1/2 months of age. Plasma RNA levels were reduced by 0.5 to 1.5 log in five of the other six infants.

CONCLUSIONS

Although further observations are needed, it appears that in infants with maternally acquired HIV-1 infection, combined treatment with zidovudine, didanosine, and nevirapine is well tolerated and has sustained efficacy against HIV-1.

Antiviral properties of palinavir, a potent inhibitor of the human immunodeficiency virus type 1 protease

Palinavir is a potent inhibitor of the human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) proteases. Replication of laboratory strains (HIV-1, HIV-2, and simian immunodeficiency virus) and HIV-1 clinical isolates is inhibited by palinavir with 50% effective concentrations ranging from 0.5 to 30 nM. The average cytotoxic concentration of palinavir (35 microM) in the various target cells indicates a favorable therapeutic index. Potent antiviral activity is retained with increased doses of virus and with clinical isolates resistant to zidovudine (AZT), didanosine (ddI), or nevirapine. Combinations of palinavir with either AZT, ddI, or nevirapine demonstrate synergy or additivity in the inhibition of HIV-1 replication. Palinavir retains anti-HIV-1 activity when administered postinfection until times subsequent to the reverse transcription step. In chronically infected CR-10 cells, palinavir blocks Gag precursor polyprotein processing completely, reducing greater than 99% of infectious particle production. The results indicate that the antiviral activity of palinavir is specific to inhibition of the viral protease and occurs at a late stage in the replicative cycle of HIV-1. On the basis of the potent in vitro activity, low-level cytotoxicity, and other data, palinavir was selected for in-depth preclinical evaluation.

A new reporter cell line to monitor HIV infection and drug susceptibility in vitro

Determination of HIV infectivity in vitro and its inhibition by antiretroviral drugs by monitoring reduction of production of p24 antigen is expensive and time consuming. Such assays also do not allow accurate quantitation of the number of infected cells over time. To develop a simple, rapid, and direct method for monitoring HIV infection, we generated a stable T-cell line (CEM) containing a plasmid encoding the green fluorescent protein (humanized S65T GFP) driven by the HIV-1 long terminal repeat. Clones were selected that displayed low constitutive background fluorescence, but a high level of GFP expression upon infection with HIV. HIV-1 infection induced a 100- to 1,000-fold increase in relative fluorescence of cells over 2 to 4 days as monitored by fluorescence microscopy, cytofluorimetry, and flow cytometry. Addition of inhibitors of reverse transcriptase, protease, and other targets at different multiplicities of infection permitted the accurate determination of drug susceptibility. This technique also permitted quantitation of infectivity of viral preparations by assessment of number of cells infected in the first round of infection. In conclusion, the CEM-GFP reporter cell line provides a simple, rapid, and direct method for monitoring HIV infectivity titers and antiretroviral drug susceptibility of syncytium-inducing strains.

Antiviral chemotherapy

Over the last few years, several new antiviral agents have been added to the chemotherapeutic armamentarium. This review discusses advances in the treatment of HIV disease in children and adults. More pronounced antiviral effects have been achieved through the study of new agents such as the protease inhibitors as well as through a better understanding of previously approved drugs, such as reverse transcriptase inhibitors.

High-dose nevirapine in previously untreated human immunodeficiency virus type 1-infected persons does not result in sustained suppression of viral replication

High-dose nevirapine treatment has been reported to confer sustained antiretroviral effects, despite a rapid development of resistance. The use of this strategy was evaluated in 20 previously untreated human immunodeficiency virus type 1 (HIV-1) p24 antigenemic persons with CD4 cell counts between 100 and 500/mm3. Treatment consisted of 400 mg of nevirapine, after a 2-week lead-in dose of 200 mg. Rash was the most frequently reported adverse event, occurring in 25%. While sustained declines in p24 antigen levels were observed in the majority, serum HIV-1 RNA load and CD4 cell counts returned to baseline values within 12 weeks in virtually all subjects. The resistance-conferring tyrosine-to-cysteine substitution at reverse transcriptase position 181 was detected after 4 weeks in most subjects. These observations suggest that plasma drug levels attained with high-dose nevirapine were not sufficient to inhibit nevirapine-resistant virus, although they were approximately 2-fold higher than reported IC50 values of resistant virus.

Antiretroviral therapy: a guide to the most important trials

AIDS and HIV infection have stimulated an unprecedented amount of research. In this review we have selected a few publications illustrating key issues. Viral load monitoring is useful because short-term changes in viremia, caused by antiretroviral treatment, predict long-term outcome. Combination therapy with AZT plus either ddl or ddC produces better results than therapy with AZT only, but the differences are slight and appeared only after several years of follow-up. In contrast, the effect of adding 3TC to AZT-containing regimens was statistically significant after only one year, halving mortality and the incidence of new AIDS-defining opportunistic infection. Adding ritonavir had a similar effect after 20 week's follow-up in far-advanced HIV infection. The most potent regimens combine AZT, 3TC, and either ritonavir or indinavir; in the majority of patients thus treated viremia became undetectable (< 500 copies/ml).

Anti-viral drug treatment: dynamics of resistance in free virus and infected cell populations

Anti-viral drug treatment of infections with the human immunodeficiency virus type I (HIV-1) usually leads to a rapid decline in the abundance of plasma virus. The effect of single drug therapy, however, is often only short-lived as the virus readily develops drug-resistant mutants. In this paper we provide analytic approximations for the rate of emergence of resistant virus. We study the decline of wildtype virus and the rise of resistant mutant virus in different compartments of the virus population such as free plasma virus, cells infected with actively replicating virus, long-lived infected cells and cells carrying defective provirus. The model results are compared with data on the rise of drug-resistant virus in three HIV-1 infected patients treated with neverapine (NVP). We find that the half-life of latently infected cells is between 10 and 20 days, whereas the half-life of cells with defective provirus is about 80 days. We also provide a crude estimate for the basic reproductive ratio of HIV-1 during NVP therapy.

Stavudine selectively induces apoptosis in HIV type 1-infected cells

We evaluated the cytotoxic effects of various human immunodeficiency virus (HIV-1) reverse transcriptase inhibitors (zidovudine, didanosine, zalcitabine, stavudine, and nevirapine) on HIV-1-infected and uninfected T cell lines. Among the compounds, only stavudine (not the others) proved to be more cytotoxic to MOLT-4/IIIB cells (MOLT-4 cells chronically infected with HIV-1) than to uninfected MOLT-4 cells. Its 50% cytotoxic concentrations were 59.8 and 2.2 microM for MOLT-4 and MOLT-4/IIIB cells, respectively. Stavudine was also more cytotoxic to CEM/ROD (CEM cells chronically infected with HIV type 2) than to uninfected CEM cells. Microscopic analysis revealed that stavudine induced apoptosis in MOLT-4/IIIB cells. Apparent chromatin condensation in the nucleus was observed by electron microscopy. Furthermore, a DNA fragmentation ladder was detected by agarose gel electrophoresis. Addition of thymidine to the culture medium could rescue the cells from stavudine-induced apoptosis. The expression of anti-apoptotic protein Bcl-2 was partially downregulated in MOLT-4/IIIB cells after treatment with stavudine. This downregulation was not identified in MOLT-4 cells. These results indicate that stavudine selectively induces apoptosis in HIV-1-infected T cells and may have potential as a novel strategy for effective chemotherapy of the acquired immune deficiency syndrome (AIDS).