Use of new T-cell-based cell lines expressing two luciferase reporters for accurately evaluating susceptibility to anti-human immunodeficiency virus type 1 drugs

Population-based nanopore sequencing of the HIV-1 pangenome to identify drug resistance mutations

HIV-1 drug resistance genotypic tests have primarily been performed by Sanger sequencing of gene segments encoding different drug target proteins. Since the number of targets has increased with the addition of a new class of antiretroviral drugs, a simple high-throughput system for assessing nucleotide sequences throughout the HIV-1 genome is required. Here, we developed a new solution using nanopore sequencing of viral pangenomes amplified by PCR. Benchmark tests using HIV-1 molecular clones demonstrated an accuracy of up to 99.9%. In addition, validation tests of our protocol in 106 clinical samples demonstrated high concordance of drug resistance and tropism genotypes (92.5% and 98.1%, respectively) between the nanopore sequencing-based results and archived clinical determinations made based on Sanger sequencing data. These results suggest that our new approach will be a powerful solution for the comprehensive survey of HIV-1 drug resistance mutations in clinical settings.

Discovery of Ten Anti-HIV Hit Compounds and Preliminary Pharmacological Mechanisms Studies

BACKGROUND

The research and development of HIV drugs is very important, but at the same time it is a long cycle and expensive system project. High-throughput drug screening systems and molecular libraries of potential hit compounds remain the main ways for the discovery of hit compounds with anti-HIV activity.

OBJECTIVE

The aim of this study was to screen out the hit compounds against HIV-1 in the natural product molecule library and the antiviral molecule library, and elucidate the molecular mechanism of their inhibition of HIV-1, so as to provide a new choice for AIDS drug research.

METHODS

In this study, a drug screening system using HIV Rev-dependent indicator cell line (Rev-A3R5-GFP reporter cells) with pseudoviruses (pNL4-3) was used. The natural drug molecule library and antiviral molecule library were screened, and preliminary drug mechanism studies were performed.

RESULTS

Ten promising hit compounds were screened. These ten molecules and their drug inhibitory IC50 were as follows: Cephaeline (0.50 μM), Yadanziolide A (8.82 μM), Bruceine D (2.48 μM), Astragaloside IV (4.30 μM), RX-3117 (1.32 μM), Harringtonine (0.63 μM), Tubercidin (0.41 μM), Theaflavine-3, 3'-digallate (0.41 μM), Ginkgetin (10.76 μM), ZK756326 (5.97 μM). The results of the Time of additions showed that except for Astragaloside IV and Theaflavine-3, 3'-digallate had a weak entry inhibition effect, and it was speculated that all ten compounds had an intracellular inhibition effect. Cephaeline, Harringtonine, Astragaloside IV, Bruceine D, and Tubercidin may have pre-reverse transcriptional inhibition. Yadanziolide A, Theaflavine-3, 3'-digallate, Ginkgetin and RX-3117 may be in the post-reverse transcriptional inhibition. The inhibitory effect of ZK 75632 may be in the reverse transcriptional process.

CONCLUSION

A drug screening system using Rev-A3R5-GFP reporter cells with pseudoviruses (pNL4-3) is highly efficient. This study provided potential hit compounds for new HIV drug research.

Sticklac-Derived Natural Compounds Inhibiting RNase H Activity of HIV-1 Reverse Transcriptase

The emergence of drug-resistant viruses is a serious concern in current chemotherapy for human immunodeficiency virus type-1 (HIV-1) infectious diseases. Hence, antiviral drugs aiming at targets that are different from those of approved drugs are still required, and the RNase H activity of HIV-1 reverse transcriptase is a suitable target. In this study, a search of a series of natural compounds was performed to identify the RNase H inhibitors. Three compounds were found to block the RNase H enzymatic activity. A laccaic acid skeleton was observed in all three natural compounds. A hydroxy phenyl group is connected to an anthraquinone backbone in the skeleton. An acetamido-ethyl, amino-carboxy-ethyl, and amino-ethyl are bound to the phenyl in laccaic acids A, C, and E, respectively. Laccaic acid C showed a 50% inhibitory concentration at 8.1 μM. Laccaic acid C also showed inhibitory activity in a cell-based viral proliferation assay. Binding structures of these three laccaic acids were determined by X-ray crystallographic analysis using a recombinant protein composed of the HIV-1 RNase H domain. Two divalent metal ions were located at the catalytic center in which one carbonyl and two hydroxy groups on the anthraquinone backbone chelated two metal ions. Molecular dynamics simulations were performed to examine the stabilities of the binding structures. Laccaic acid C showed the strongest binding to the catalytic site. These findings will be helpful for the design of potent inhibitors with modification of laccaic acids to enhance the binding affinity.

HIV-1 reverse transcriptase and protease mutations for drug-resistance detection among treatment-experienced and naïve HIV-infected individuals

Background

The presence of drug resistance mutations (DRMs) against antiretroviral agents is one of the main concerns in the clinical management of individuals with human immunodeficiency virus-1 (HIV-1) infection, especially in regions of the world where treatment options are limited. The current study aimed at assessing the prevalence of HIV-1 DRMs among naïve and treatment-experienced HIV-1-infected patients in Iran.

Methods

From April 2013 to September 2018, the HIV-1 protease and reverse transcriptase genes were amplified and sequenced in plasma specimens of 60 newly diagnosed antiretroviral-naive individuals and 46 participants receiving antiretroviral therapies (ARTs) for at least six months with an HIV viral load of more than 1000 IU/mL to determine the HIV-1 DRMs and subtypes.

Results

Among the 60 treatment-naïve HIV-1-infected participants, 8.3% were infected with HIV-1 variants with surveillance DRMs (SDRMs). The SDRMs, D67N and D67E, belonged to the NRTIs class in two patients and K103N and V106A belonged to the NNRTIs class in three patients. The phylogenetic analysis showed that 91.7% of the subjects were infected with subtype CRF35_AD, followed by subtype B (5.0%) and CRF01_AE (3.3%). Among the 46 ART-experienced participants, 33 (71.7%) carried HIV-1 variants with SDRMs (9.1% against PIs, 78.8% against NRTIs, and 100% against NNRTIs). M46I and I47V were the most common mutations for PIs, M184V was the most common mutation for the NRTIs, and K103N/S was the most common mutation for NNRTIs. Phylogenetic analysis of the polymerase region showed that all of the 46 HIV-1-infected patients who failed on ART carried CRF35_AD.

Conclusions

The moderate prevalence of SDRMs (8.3%) in treatment-naïve and ART-failed (77.1%) Iranian patients with HIV-1-infection emphasizes the need for systematic viral load monitoring, expanding drug resistance testing, carefully surveilling individuals on ART regimens, and facilitating access to new antiretrovirals by health authorities.

Discovery of 4-oxoquinolines, a new chemical class of anti-HIV-1 compounds

Antiretroviral therapy (ART) against HIV-1 infection offers the promise of controlling disease progression and prolonging the survival of HIV-1-infected patients. However, even the most potent ART regimens available today cannot cure HIV-1. Because patients will be exposed to ART for many years, physicians and researchers must anticipate the emergence of drug-resistant HIV-1, potential adverse effects of the current drugs, and need for future drug development. In this study, we screened a small-molecule compound library using cell-based anti-HIV-1 assays and discovered a series of novel anti-HIV-1 compounds, 4-oxoquinolines. These compounds exhibited potent anti-HIV-1 activity (EC₅₀ < 0.1 μM) with high selectivity indexes (CC₅₀/EC₅₀ > 2500) and favorable pharmacokinetic profiles in mice. Surprisingly, our novel compounds have a chemical backbone similar to the clinically used integrase (IN) strand transfer inhibitor (INSTI) elvitegravir, although they lack the crucial 3-carboxylate moiety needed for the common INSTI diketo motif. Indeed, the new 4-oxoquinoline derivatives have no detectable INSTI activity. In addition, various drug-resistant HIV-1 strains did not display cross resistance to these compounds. Interestingly, time-of-addition experiments indicated that the 4-oxoquinoline derivative remains its anti-HIV-1 activity even after the viral integration stage. Furthermore, the compounds significantly suppressed p24 antigen production in HIV-1 latently infected cells exposed with tumor necrosis factor alpha. These findings suggest that our 4-oxoquinoline derivatives with no 3-carboxylate moiety may become novel lead compounds in the development of anti-HIV-1 drugs.

Screening Method for Anti-Colon Cancer Drugs Using Two Sensor Cell Lines with Human β4-Galactosyltransferase 4 Gene Promoters

The increased expression of β4-galactosyltransferase (β4GalT) 4 is closely associated with poor prognosis of colon cancer. Recently, we showed that the expression of the β4GalT4 gene is regulated by the 0.17 kb core promoter region containing one binding site for Specificity protein 1 (Sp1). To develop a screening method for anti-colon cancer drugs, two sensor cell lines having the luciferase gene under the control of two β4GalT4 gene promoters that differed in length were established from SW480 human colon cancer cells. The hGT4-0.17-sensor cells possessed the luciferase reporter driven by the 0.17 kb promoter, while the hGT4-0.3-sensor cells possessed the luciferase reporter driven by the 0.3 kb promoter containing one binding site each for colon cancer-related transcription factors including activator protein 2, E2F, caudal-related homeobox transcription factors, and Runt-related transcription factors besides Sp1. Upon treatment with mitogen-activated protein kinase signaling inhibitor U0126, the promoter activities of the hGT4-0.3-sensor cells decreased significantly, while those of the hGT4-0.17-sensor cells remained unchanged. These results suggest that the responsiveness to U0126 differs between two sensor cell lines due to the different regulation of the luciferase reporters. This study provides the screening method for anti-colon cancer drugs by the combination of two sensor cell lines.

Prediction of luciferase inhibitors by the high-performance MIEC-GBDT approach based on interaction energetic patterns

The MIEC-GBDT model can be used as a powerful tool to identify potential interference compounds in luciferase-based high-throughput screening.

A novel dual luciferase assay for the simultaneous monitoring of HIV infection and cell viability

Human immunodeficiency virus type 1 (HIV-1) reporter cell lines are critical tools for drug development. However, one disadvantage of HIV-1 reporter cell lines is that reductions in reporter gene activity need to be normalized to cytotoxicity, i.e., live cell numbers. Here, we developed a dual luciferase assay based on a R. reniformis luciferase (hRLuc)-expressing R5-type HIV-1 (NLAD8-hRLuc) and a CEM cell line expressing CCR5 and firefly luciferase (R5CEM-FiLuc). The NLAD8-hRLuc reporter virus was replication competent in peripheral blood mononuclear cells. The level of hRLuc was correlated with p24 antigen levels (p<0.001, R=0.862). The target cell line, R5CEM-FiLuc, stably expressed the firefly luciferase (FiLuc) reporter gene and allowed the simultaneous monitoring of compound cytotoxicity. The dual reporter assay combining a NLAD8-hRLuc virus with R5CEM-FiLuc cells permitted the accurate determination of drug susceptibility for entry, reverse transcriptase, integrase, and protease inhibitors at different multiplicities of infection. This dual reporter assay provides a rapid and direct method for the simultaneous monitoring of HIV infection and cell viability.

Unique Flap Conformation in an HIV-1 Protease with High-Level Darunavir Resistance

Darunavir (DRV) is one of the most powerful protease inhibitors (PIs) for treating human immunodeficiency virus type-1 (HIV-1) infection and presents a high genetic barrier to the generation of resistant viruses. However, DRV-resistant HIV-1 infrequently emerges from viruses exhibiting resistance to other protease inhibitors. To address this resistance, researchers have gathered genetic information on DRV resistance. In contrast, few structural insights into the mechanism underlying DRV resistance are available. To elucidate this mechanism, we determined the crystal structure of the ligand-free state of a protease with high-level DRV resistance and six DRV resistance-associated mutations (including I47V and I50V), which we generated by in vitro selection. This crystal structure showed a unique curling conformation at the flap regions that was not found in the previously reported ligand-free protease structures. Molecular dynamics simulations indicated that the curled flap conformation altered the flap dynamics. These results suggest that the preference for a unique flap conformation influences DRV binding. These results provide new structural insights into elucidating the molecular mechanism of DRV resistance and aid to develop PIs effective against DRV-resistant viruses.

APOBEC3D and APOBEC3F potently promote HIV-1 diversification and evolution in humanized mouse model

Several APOBEC3 proteins, particularly APOBEC3D, APOBEC3F, and APOBEC3G, induce G-to-A hypermutations in HIV-1 genome, and abrogate viral replication in experimental systems, but their relative contributions to controlling viral replication and viral genetic variation in vivo have not been elucidated. On the other hand, an HIV-1-encoded protein, Vif, can degrade these APOBEC3 proteins via a ubiquitin/proteasome pathway. Although APOBEC3 proteins have been widely considered as potent restriction factors against HIV-1, it remains unclear which endogenous APOBEC3 protein(s) affect HIV-1 propagation in vivo. Here we use a humanized mouse model and HIV-1 with mutations in Vif motifs that are responsible for specific APOBEC3 interactions, DRMR/AAAA (4A) or YRHHY/AAAAA (5A), and demonstrate that endogenous APOBEC3D/F and APOBEC3G exert strong anti-HIV-1 activity in vivo. We also show that the growth kinetics of 4A HIV-1 negatively correlated with the expression level of APOBEC3F. Moreover, single genome sequencing analyses of viral RNA in plasma of infected mice reveal that 4A HIV-1 is specifically and significantly diversified. Furthermore, a mutated virus that is capable of using both CCR5 and CXCR4 as entry coreceptor is specifically detected in 4A HIV-1-infected mice. Taken together, our results demonstrate that APOBEC3D/F and APOBEC3G fundamentally work as restriction factors against HIV-1 in vivo, but at the same time, that APOBEC3D and APOBEC3F are capable of promoting viral diversification and evolution in vivo.

Mutation can produce three outcomes in viruses: detrimental, neutral, or beneficial. The first one leads to abrogation of virus replication because of error catastrophe, while the last one lets the virus escape from anti-viral immune system or adapt to the host. Human APOBEC3D, APOBEC3F, and APOBEC3G are cellular cytidine deaminases which cause G-to-A mutations in HIV-1 genome. Here we use a humanized mouse model and demonstrate that endogenous APOBEC3F and APOBEC3G induce G-to-A hypermutation in viral genomes and exert strong anti-HIV-1 activity in vivo. We also reveal that endogenous APOBEC3D and/or APOBEC3F induce viral diversification, which can lead to the emergence of a mutated virus that converts its coreceptor usage. Our results suggest that APOBEC3D and APOBEC3F are capable of promoting viral diversification and functional evolution in vivo.

miR-326 is downstream of Sonic hedgehog signaling and regulates the expression of Gli2 and smoothened

Sonic hedgehog (Shh) is expressed and secreted from the embryonic lung epithelium and acts on the adjacent mesenchymal cells via its receptor Patched (Ptch)/Smoothened (Smo) and transcriptional effectors Gli proteins. Genetic studies showed that the Shh pathway plays critical roles in mouse lung development. However, little is known about microRNAs (miRNAs) downstream of Shh in embryonic lungs. Here we profiled miRNAs in embryonic lung cultures treated with cyclopamine, a specific Smo antagonist or with Smo agonist by next-generation of sequencing. We then performed functional screening to examine whether some of these miRNAs can modulate the induction of Gli-responsive luciferase by Shh treatment. These analyses revealed that expression of miR-326 and its host gene, Arrestin β1, is selectively enriched in embryonic lung mesenchymal cells and is specifically influenced by Shh activity. Furthermore, functional analyses showed that miR-326 acts as a negative modulator for Shh signaling by directly targeting Smo and Gli2. Together, these findings suggest a novel miR-326-negative feedback loop in regulating the activity of Shh signaling.

HIV-1 drug-resistance surveillance among treatment-experienced and -naïve patients after the implementation of antiretroviral therapy in Ghana

Background

Limited HIV-1 drug-resistance surveillance has been carried out in Ghana since the implementation of antiretroviral therapy (ART). This study sought to provide data on the profile of HIV-1 drug resistance in ART-experienced and newly diagnosed individuals in Ghana.

Methods

Samples were collected from 101 HIV-1-infected patients (32 ART-experienced cases with virological failure and 69 newly diagnosed ART-naïve cases, including 11 children), in Koforidua, Eastern region of Ghana, from February 2009 to January 2010. The pol gene sequences were analyzed by in-house HIV-1 drug-resistance testing.

Results

The most prevalent HIV-1 subtype was CRF02_AG (66.3%, 67/101) followed by unique recombinant forms (25.7%, 26/101). Among 31 ART-experienced adults, 22 (71.0%) possessed at least one drug-resistance mutation, and 14 (45.2%) had two-class-resistance to nucleoside and non-nucleoside reverse-transcriptase inhibitors used in their first ART regimen. Importantly, the number of accumulated mutations clearly correlated with the duration of ART. The most prevalent mutation was lamivudine-resistance M184V (n = 12, 38.7%) followed by efavirenz/nevirapine-resistance K103N (n = 9, 29.0%), and zidovudine/stavudine-resistance T215Y/F (n = 6, 19.4%). Within the viral protease, the major nelfinavir-resistance mutation L90M was found in one case. No transmitted HIV-1 drug-resistance mutation was found in 59 ART-naïve adults, but K103N and G190S mutations were observed in one ART-naïve child.

Conclusions

Despite expanding accessibility to ART in Eastern Ghana, the prevalence of transmitted HIV-1 drug resistance presently appears to be low. As ART provision with limited options is scaled up nationwide in Ghana, careful monitoring of transmitted HIV-1 drug resistance is necessary.

Identification, synthesis, and biological evaluation of the metabolites of 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36), a promising rexinoid lead compound for the development of cancer chemotherapeutic and chemopreventive agents

Activation of the retinoid X receptor (RXR), which is involved in cell proliferation, differentiation, and apoptosis, is a strategy for cancer chemotherapy and chemoprevention, and 3-amino-6-(3'-aminopropyl)-5H-indeno[1,2-c]isoquinoline-5,11-(6H)dione (AM6-36) (3) is among the few RXR ligands known. The presently reported studies of 3 include its binding to human plasma proteins, metabolic stability using human liver microsomes, metabolism by human liver microsomes and hepatocytes, and in vivo disposition in rat serum, liver, and mammary tissue. Compound 3 was 75% bound to human plasma proteins, and its metabolic stability was much greater than propranolol. One phase I metabolite was formed by human liver microsomes, seven phase I and II metabolites were formed by human hepatocytes, and five metabolites were detected in rat serum and liver after oral administration. The putative metabolites predicted using LC-MS-MS were synthesized to confirm their structures and to provide sufficient material for investigation of induction of RXRE transcriptional activity and inhibition of NFκB.

In vitro activities of candidate microbicides against cell-associated HIV

Most research on HIV transmission and microbicides focuses on the inhibition of cell-free virus (CFV) present in genital secretions. However, an effective microbicide should also block the transmission of cell-associated virus (CAV) originating from seminal T cells and macrophages. Because inhibition of CAV remains controversial, especially for viral entry inhibitors, we developed a novel in vitro assay to evaluate the activities of different classes of candidate microbicides against cell-free HIV and HIV-infected leukocytes (i.e., resting peripheral blood mononuclear cells [PBMC], activated PBMC, and monocyte-derived macrophages). The assay is based on two CD4(+) CXCR4(+) T-cell lines (R5MaRBLE and X4MaRBLE) that both contain a firefly luciferase reporter gene but differ in the expression of the CCR5 coreceptor. Consequently, the quantification of the luciferase activities and the Gag p24 concentrations in cocultures of R5-tropic HIV-infected leukocytes with each cell line separately allowed us to discriminate between the infection of the cell lines (i.e., target cells), the ongoing infection in the HIV-infected leukocytes (i.e., effector cells), and the total infection of the coculture (i.e., effector plus target cells). All 14 antiretrovirals tested were able to block target cell infection by all three sources of CAV, although a small decrease in activity (2- to 18-fold) was observed for all entry inhibitors. On the other hand, the production of Gag p24 by the infected effector cells could be blocked only by protease inhibitors. Overall, these results show that entry and protease inhibitors are eligible drug classes for inclusion in future combination microbicides.

Within-host co-evolution of Gag P453L and protease D30N/N88D demonstrates virological advantage in a highly protease inhibitor-exposed HIV-1 case

To better understand the mechanism of HIV group-specific antigen (Gag) and protease (PR) co-evolution in drug-resistance acquisition, we analyzed a drug-resistance case by both bioinformatics and virological methods. We especially considered the quality of sequence data and analytical accuracy by introducing single-genome sequencing (SGS) and Spidermonkey/Bayesian graphical models (BGM) analysis, respectively. We analyzed 129 HIV-1 Gag-PR linkage sequences obtained from 8 time points, and the resulting sequences were applied to the Spidermonkey co-evolution analysis program, which identified ten mutation pairs as significantly co-evolving. Among these, we focused on associations between Gag-P453L, the P5' position of the p1/p6 cleavage-site mutation, and PR-D30N/N88D nelfinavir-resistant mutations, and attempted to clarify their virological significance in vitro by constructing recombinant clones. The results showed that P453L(Gag) has the potential to improve replication capacity and the Gag processing efficiency of viruses with D30N(PR)/N88D(PR) but has little effect on nelfinavir susceptibility. Homology modeling analysis suggested that hydrogen bonds between the 30th PR residue and the R452Gag are disturbed by the D30N(PR) mutation, but the impaired interaction is compensated by P453L(Gag) generating new hydrophobic interactions. Furthermore, database analysis indicated that the P453L(Gag)/D30N(PR)/N88D(PR) association was not specific only to our clinical case, but was common among AIDS patients.

EASY-HIT: HIV full-replication technology for broad discovery of multiple classes of HIV inhibitors

HIV replication assays are important tools for HIV drug discovery efforts. Here, we present a full HIV replication system (EASY-HIT) for the identification and analysis of HIV inhibitors. This technology is based on adherently growing HIV-susceptible cells, with a stable fluorescent reporter gene activated by HIV Tat and Rev. A fluorescence-based assay was designed that measures HIV infection by two parameters relating to the early and the late phases of HIV replication, respectively. Validation of the assay with a panel of nine reference inhibitors yielded effective inhibitory concentrations consistent with published data and allowed discrimination between inhibitors of early and late phases of HIV replication. Finer resolution of the effects of reference drugs on different steps of HIV replication was achieved in secondary time-of-addition assays. The EASY-HIT assay yielded high Z' scores (>0.9) and signal stabilities, confirming its robustness. Screening of the LOPAC(1280) library identified 10 compounds (0.8%), of which eight were known to inhibit HIV, validating the suitability of this assay for screening applications. Studies evaluating anti-HIV activities of natural products with the EASY-HIT technology led to the identification of three novel inhibitory compounds that apparently act at different steps of HIV-1 replication. Furthermore, we demonstrate successful evaluation of plant extracts for HIV-inhibitory activities, suggesting application of this technology for the surveillance of biological extracts with anti-HIV activities. We conclude that the EASY-HIT technology is a versatile tool for the discovery and characterization of HIV inhibitors.

Comparative study of the persistence of anti-HIV activity of deoxynucleoside HIV reverse transcriptase inhibitors after removal from culture

Background

Most in vitro assays of drug potency may not adequately predict the performance in vivo. Methods to assess the persistence of antiviral activity of deoxynucleoside analogs, which require intracellular activation to the active metabolites that can persist in cells, will be important for designing dosages, combination regimens, and assessing treatment compliance. Using an HIV-IIIB/TZM-bl indicator cell culture system, we assessed the ability of an inhibitor to protect cells from infection and to delay viral rebound after removal of inhibitor from culture.

Results

The order of protection of cells from HIV-infection was 4'-Ed4T > LFD4C > DDI > D4T > 3TC > AZT > FTC > NVP. The fold-increase in EC₅₀ to delay viral rebound was DDI < 4'-Ed4T < LFD4C < FTC < D4T < 3TC < NVP < AZT. The ranking of persistence of anti-HIV activity of the inhibitors based on the two-component assay was DDI > 4'-Ed4T > LFD4C > FTC = D4T > 3TC > NVP > AZT.

Conclusion

The persistence ranking was derived from assays based on measures of single viral replication-cycle and cumulative inhibition at multiple time-points. Therefore, a better indicator of the pharmacodynamic property of an inhibitor. The persistence of anti-HIV activity assay may complement in vitro potency assays to better predict in vivo performance of nucleoside analogs.

Plasmodium falciparum: development of a transgenic line for screening antimalarials using firefly luciferase as the reporter

High-throughput screening (HTS) of small-molecule libraries against pharmacological targets is a key strategy of contemporary drug discovery. This study reports a simple, robust, and cell-based luminescent method for assaying antimalarial drugs. Using transfection technology, we generated a stable Plasmodium falciparum line with high levels of firefly luciferase expression. A luciferase assay based on this parasite line was optimized in a 96-well plate format and used to compare with the standard [(3)H] hypoxanthine radioisotope method. The 50% inhibitory concentrations (IC(50)s) of chloroquine, artesunate, artemether, dihydroartemisinin and curcumin obtained by these two methods were not significantly different (P>0.05, ANOVA). In addition, this assay could be performed conveniently with a luminescence plate reader using unsynchronized stages within as early as 12h. Furthermore, the luciferase assay is robust with a Z' score of 0.77-0.92, which suggests the feasibility for further miniaturization and automation.