Inflammatory progressive multifocal leukoencephalopathy with human T-cell lymphotropic virus-1 coinfection.

A middle-aged man with progressive multifocal leukoencephalopathy (PML) in a human T-cell lymphotropic virus type-1 (HTLV-1) carrier on haemodialysis presented with mild dysarthria and ataxia. Brain MRI revealed asymmetric T2-hyperintense lesions in the cerebral white matter, cerebellum and brainstem. A small amount of JC virus (JCV) genome in cerebrospinal fluid was detected by PCR and cerebellar biopsy demonstrated JCV-DNA presence. Pathological findings showed demyelinating lesions and glial cells with mildly enlarged nuclei, accompanied by T-lymphocytes, neutrophils and plasma cell infiltration. The CD4+/CD8+ratio was 0.83. High-dose corticosteroid therapy was effective for inflammatory PML lesions, and the administration of mefloquine combined with mirtazapine led to favourable outcome. The encephalitis in this case is considered to have occurred secondarily to JCV infection in the presence of HTLV-1 infection. Therefore, it is crucial to investigate the presence of HTLV-1 in order to understand the aetiology of this brain inflammation.

Comparison of lumefantrine, mefloquine, and piperaquine concentrations between capillary plasma and venous plasma samples in pregnant women with uncomplicated falciparum and vivax malaria.

Capillary samples offer practical benefits compared with venous samples for the measurement of drug concentrations, but the relationship between the two measures varies between different drugs. We measured the concentrations of lumefantrine, mefloquine, piperaquine in 270 pairs of venous plasma and concurrent capillary plasma samples collected from 270 pregnant women with uncomplicated falciparum or vivax malaria. The median and range of venous plasma concentrations included in this study were 447.5 ng/mL (8.81-3,370) for lumefantrine (day 7, n = 76, median total dose received 96.0 mg/kg), 17.9 ng/mL (1.72-181) for desbutyl-lumefantrine, 1,885 ng/mL (762-4,830) for mefloquine (days 3-21, n = 90, median total dose 24.9 mg/kg), 641 ng/mL (79.9-1,950) for carboxy-mefloquine, and 51.8 ng/mL (3.57-851) for piperaquine (days 3-21, n = 89, median total dose 52.2 mg/kg). Although venous and capillary plasma concentrations showed a high correlation (Pearson's correlation coefficient: 0.90-0.99) for all antimalarials and their primary metabolites, they were not directly interchangeable. Using the concurrent capillary plasma concentrations and other variables, the proportions of venous plasma samples predicted within a ±10% precision range was 34% (26/76) for lumefantrine, 36% (32/89) for desbutyl-lumefantrine, 74% (67/90) for mefloquine, 82% (74/90) for carboxy-mefloquine, and 24% (21/89) for piperaquine. Venous plasma concentrations of mefloquine, but not lumefantrine and piperaquine, could be predicted by capillary plasma samples with an acceptable level of agreement. Capillary plasma samples can be utilized for pharmacokinetic and clinical studies, but caution surrounding cut-off values is required at the individual level.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT01054248.

Mefloquine enhances the efficacy of anti-PD-1 immunotherapy via IFN-γ-STAT1-IRF1-LPCAT3-induced ferroptosis in tumors.

BACKGROUND: Ferroptosis plays an important role in enhancing the efficacy of anti-programmed cell death 1 (PD-1) immunotherapy; however, the molecular mechanisms by which tumor ferroptosis sensitizes melanoma and lung cancer to anti-PD-1 immunotherapy have not been elucidated. METHODS: Cytotoxicity assays, colony formation assays, flow cytometry and animal experiments were used to evaluate the effects of mefloquine (Mef) on survival and ferroptosis in melanoma and lung cancer. RNA sequencing, Real-time quantitative PCR (qRT-PCR), western blotting, chromatin immunoprecipitation-qPCR and flow cytometry were used to determine the molecular mechanisms by which Mef regulates lysophosphatidylcholine acyltransferase 3 (LPCAT3). The relationship between LPCAT3 and the efficacy of anti-PD-1 immunotherapy was verified via a clinical database and single-cell RNA sequencing (ScRNA-Seq). RESULTS: In this study, we discovered that Mef induces ferroptosis. Furthermore, treatment with Mef in combination with T-cell-derived interferon-γ (IFN-γ) enhanced tumor ferroptosis and sensitized melanoma and lung cancer cells to anti-PD-1 immunotherapy. Mechanistically, Mef upregulated the expression of LPCAT3, a key gene involved in lipid peroxidation, by activating IFN-γ-induced STAT1-IRF1 signaling, and knocking down LPCAT3 impaired the induction of ferroptosis by Mef+IFN-γ. Clinically, analysis of the transcriptome and single-cell sequencing results in patients with melanoma showed that LPCAT3 expression was significantly lower in patients with melanoma than in control individuals, and LPCAT3 expression was positively correlated with the efficacy of anti-PD-1 immunotherapy. CONCLUSIONS: In conclusion, our study demonstrated a novel mechanism by which LPCAT3 is regulated, and demonstrated that Mef is a highly promising new target that can be utilized to enhance the efficacy of anti-PD-1 immunotherapy.

Whole genome sequencing identifies novel mutations in malaria parasites resistant to artesunate (ATN) and to ATN + mefloquine combination.

Introduction: The global evolution of resistance to Artemisinin-based Combination Therapies (ACTs) by malaria parasites, will severely undermine our ability to control this devastating disease. Methods: Here, we have used whole genome sequencing to characterize the genetic variation in the experimentally evolved Plasmodium chabaudi parasite clone AS-ATNMF1, which is resistant to artesunate + mefloquine. Results and discussion: Five novel single nucleotide polymorphisms (SNPs) were identified, one of which was a previously undescribed E738K mutation in a 26S proteasome subunit that was selected for under artesunate pressure (in AS-ATN) and retained in AS-ATNMF1. The wild type and mutated three-dimensional (3D) structure models and molecular dynamics simulations of the P. falciparum 26S proteasome subunit Rpn2 suggested that the E738K mutation could change the toroidal proteasome/cyclosome domain organization and change the recognition of ubiquitinated proteins. The mutation in the 26S proteasome subunit may therefore contribute to altering oxidation-dependent ubiquitination of the MDR-1 and/or K13 proteins and/or other targets, resulting in changes in protein turnover. In light of the alarming increase in resistance to artemisin derivatives and ACT partner drugs in natural parasite populations, our results shed new light on the biology of resistance and provide information on novel molecular markers of resistance that may be tested (and potentially validated) in the field.

Enhanced anti-malarial efficacy of mefloquine delivered via cationic liposome in a murine model of experimental cerebral malaria.

Malaria is a longstanding global health challenge that continues to afflict over 90 countries located in tropical and subtropical regions of the globe. The rise of drug-resistant malarial parasites has curtailed the therapeutic efficacy of a number of once-effective anti-malarials, including mefloquine. In the present study, we have taken advantage of drug encapsulation approach to elevate the anti-malarial potential of mefloquine. Encouragingly, our findings unveil that liposomal formulations of mefloquine outperform equivalent doses of free mefloquine, both in laboratory cultures and in a murine model of malaria. Intriguingly, a cationic liposomal mefloquine formulation, administered at four successive doses of 3 mg/kg body weight, achieves complete resolution of cerebral malaria in the murine model while avoiding noticeable toxic repercussions. Altogether, our study furnishes pre-clinical validation for a therapeutic strategy that can remarkably enhance the drug efficacy, offering a revitalizing solution for failing anti-malarials.

Mefloquine improves pulmonary fibrosis by inhibiting the KCNH2/Jak2/Stat3 signaling pathway in macrophages.

Idiopathic pulmonary fibrosis (IPF) is a life-threatening disease characterized by severe pulmonary fibrosis, for which there is an urgent need for effective therapeutic agents. Mefloquine (Mef) is a quinoline compound primarily used for the treatment of malaria. However, high doses (>25 mg/kg) may lead to side effects such as cardiotoxicity and psychiatric disorders. Here, we found that low-dose Mef (5 mg/kg) can safely and effectively treat IPF mice. Functionally, Mef can improve the pulmonary function of IPF mice (PIF, PEF, EF50, VT, MV, PENH), alleviating pulmonary inflammation and fibrosis by inhibiting macrophage activity. Mechanically, Mef probably regulates the Jak2/Stat3 signaling pathway by binding to the 492HIS site of Potassium voltage-gated channel subfamily H member 2 (KCNH2) protein in macrophages, inhibiting the secretion of macrophage inflammatory and fibrotic factors. In summary, Mef may inhibit macrophage activity by binding to KCNH2 protein, thereby slowing down the progress of IPF.

Antimalarial artesunate-mefloquine versus praziquantel in African children with schistosomiasis: an open-label, randomized controlled trial.

Schistosomiasis treatment entirely relies on a single drug, praziquantel, prompting research into alternative therapeutics. Here we evaluated the efficacy and safety of the antimalarial combination artesunate-mefloquine for the treatment of schistosomiasis in a proof-of-concept, pragmatic, open-label, randomized controlled trial in primary schools of six villages endemic for schistosomiasis in northern Senegal. Children (6-14 years) were eligible if Schistosoma eggs were detected by microscopy in urine and/or stool. In total, 726 children were randomized 1:1 to praziquantel (standard care: 40 mg kg-1 single dose; n = 364) or to artesunate-mefloquine (antimalarial dosage: artesunate 4 mg kg-1 and mefloquine 8 mg kg-1 daily for three consecutive days; n = 362). Eight children not meeting the inclusion criteria were excluded from efficacy analysis. Median age of the remaining 718 participants was 9 years; 399 (55.6%) were male, and 319 (44.4%) female; 99.3% were infected with Schistosoma haematobium and 15.2% with S. mansoni. Primary outcomes were cure rate, assessed by microscopy, and frequency of drug-related adverse effects of artesunate-mefloquine versus praziquantel at 4 weeks after treatment. Cure rate was 59.6% (208/349) in the artesunate-mefloquine arm versus 62.1% (211/340) in the praziquantel arm. The difference of -2.5% (95% confidence interval (CI) -9.8 to 4.8) met the predefined criteria of noninferiority (margin set at 10%). All drug-related adverse events were mild or moderate, and reported in 28/361 children receiving artesunate-mefloquine (7.8%; 95% CI 5.4 to 11.0) versus 8/363 (2.2%; 95% CI 1.1 to 4.3) receiving praziquantel (P < 0.001). Artesunate-mefloquine at antimalarial dosage was moderately safe and noninferior to standard-care praziquantel for the treatment of schistosomiasis, predominantly due to S. haematobium. Multicentric trials in different populations and epidemiological settings are needed to confirm these findings. ClinicalTrials.gov identifier: NCT03893097 .

Artesunate-mefloquine therapy for uncomplicated Plasmodium falciparum malaria: an updated systematic review and meta-analysis of efficacy and safety.

To provide a continuous update on the safety and efficacy of artesunate-mefloquine (ASMQ) compared with other artemisinin combination therapy (ACT) schemes used in the treatment of uncomplicated malaria caused by Plasmodium falciparum, this study updated and expanded the results of the systematic literature review published in 2016. Only randomised controlled clinical trials published from 1 January 2001 to 12 June 2023 from five databases were included in this study. The results related to efficacy, expressed through RR, were summarized in meta-analyses, performed according to the compared ACTs and with the intention-to-treat and per-protocol analyses. The results related to safety were synthesized in a descriptive manner. Thirty-two studies were included, of which 24 had been analysed in the 2016 review and eight new ones were added. Although the methodological quality of most studies was considered moderate, the body of evidence gathered indicates that ASMQ continues to be safe and effective for the treatment of uncomplicated infections caused by P. falciparum compared with other ACTs. However, the inclusion of two new studies, which identified failure rates exceeding 10%, suggests a possible reduction in the efficacy of ASMQ in the analysed locations. The incidence of serious adverse effects, such as seizure, encephalopathy and cardiac arrhythmia, was infrequent in both the ASMQ group and the comparison groups. After including new evidence, ASMQ is still recommended as a first-line treatment of uncomplicated malaria caused by P. falciparum, although local aspects need to be considered.

Mefloquine-Induced Inner Ear Damage and Preventive Effects of Electrical Stimulation: An Electrophysiological Study.

INTRODUCTION: Mefloquine is an antimalarial medicine used to prevent and treat malaria. This medicine has some side effects, including ototoxicity. This study, which was designed in two phases, aimed to investigate the side effects of mefloquine and evaluate the preventive effects of electrical stimulation on these side effects. METHODS: In the first phase, two doses of mefloquine (50 and 200 µM) were injected into male rats, and after 7 days, they were evaluated by an auditory brainstem response (ABR) test. In the second phase, electrical stimulation was applied for 10 days, and then a toxic dose of mefloquine was injected. Similar to the first phase of the study, the animals were evaluated by an ABR test after 7 days. RESULTS: In the first phase, the results showed that a high dose of mefloquine increased the ABR threshold and wave I latency; however, these changes were not observed in the second phase. CONCLUSION: Application of electrical stimulation could prevent the ototoxic effects of mefloquine. According to the findings of the present study, electrical stimulation can be used as a preconditioner to prevent the ototoxic effects of mefloquine.

Synthesis, antiproliferative and antiplasmodial evaluation of new chloroquine and mefloquine-based harmiquins.

Here we present the synthesis and evaluation of the biological activity of new hybrid compounds, ureido-type (UT) harmiquins, based on chloroquine (CQ) or mefloquine (MQ) scaffolds and ß-carboline alkaloid harmine against cancer cell lines and Plasmodium falciparum. The hybrids were prepared from the corresponding amines by 1,1'-carbonyldiimidazole (CDI)-mediated synthesis. In vitro evaluation of the biological activity of the title compounds revealed two hit compounds. Testing of the antiproliferative activity of the new UT harmiquins, and previously prepared triazole-(TT) and amide-type (AT) CQ-based harmiquins, against a panel of human cell lines, revealed TT harmiquine 16 as the most promising compound, as it showed pronounced and selective activity against the tumor cell line HepG2 (IC 50 = 5.48 ± 3.35 µmol L-1). Screening of the antiplasmodial activities of UT harmiquins against erythrocytic stages of the Plasmodium life cycle identified CQ-based UT harmiquine 12 as a novel antiplasmodial hit because it displayed low IC 50 values in the submicromolar range against CQ-sensitive and resistant strains (IC 50 0.06 ± 0.01, and 0.19 ± 0.02 µmol L-1, respectively), and exhibited high selectivity against Plasmodium, compared to mammalian cells (SI = 92).

Antiepileptogenic and neuroprotective effect of mefloquine after experimental status epilepticus.

Acquired temporal lobe epilepsy (TLE) characterized by spontaneous recurrent seizures (SRS) and hippocampal inhibitory neuron dysfunction is often refractory to current therapies. Gap junctional or electrical coupling between inhibitory neurons has been proposed to facilitate network synchrony and intercellular molecular exchange suggesting a role in both seizures and neurodegeneration. While gap junction blockers can limit acute seizures, whether blocking neuronal gap junctions can modify development of chronic epilepsy has not been examined. This study examined whether mefloquine, a selective blocker of Connexin 36 gap junctions which are well characterized in inhibitory neurons, can limit epileptogenesis and related cellular and behavioral pathology in a model of acquired TLE. A single, systemic dose of mefloquine administered early after pilocarpine-induced status epilepticus (SE) in rat reduced both development of SRS and behavioral co-morbidities. Immunostaining for interneuron subtypes identified that mefloquine treatment likely reduced delayed inhibitory neuronal loss after SE. Uniquely, parvalbumin expressing neurons in the hippocampal dentate gyrus appeared relatively resistant to early cell loss after SE. Functionally, whole cell patch clamp recordings revealed that mefloquine treatment preserved inhibitory synaptic drive to projection neurons one week and one month after SE. These results demonstrate that mefloquine, a drug already approved for malaria prophylaxis, is potentially antiepileptogenic and can protect against progressive interneuron loss and behavioral co-morbidities of epilepsy.

Molecular surveillance of Plasmodium falciparum drug-resistance markers in Vietnam using multiplex amplicon sequencing (2000-2016).

Emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapies (ACT) is a major challenge for Greater Mekong Subregion countries in their goal to eliminate malaria by 2030. Tools to efficiently monitor drug resistance beyond resource-demanding therapeutic efficacy studies are necessary. A custom multiplex amplicon sequencing assay based on Illumina technology was designed to target the marker of partial resistance to artemisinin (K13), five candidate modulators of artemisinin resistance, the marker of resistance to chloroquine (crt), and four neutral microsatellite loci. The assay was used to genotype 635 P. falciparum-positive blood samples collected across seven provinces of Vietnam and one of Cambodia between 2000 and 2016. Markers of resistance to artemisinin partner-drugs piperaquine (copy number of plasmepsin-2) and mefloquine (copy number of multidrug-resistance 1) were determined by qPCR. Parasite population structure was further assessed using a 101-SNP barcode. Validated mutations of artemisinin partial resistance in K13 were found in 48.1% of samples, first detection was in 2000, and by 2015 prevalence overcame > 50% in Central Highlands and Binh Phuoc province. K13-C580Y variant became predominant country-wide, quickly replacing an outbreak of K13-I543T in Central Highlands. Mutations in candidate artemisinin resistance modulator genes paralleled the trends of K13 mutants, whereas resistance to piperaquine and mefloquine remained low (≈ 10%) by 2015-2016. Genomic tools applied to malaria surveillance generate comprehensive information on dynamics of drug resistance and population structure and reflect drug efficacy profiles from in vivo studies.

[A case of progressive multifocal leukoencephalopathy associated with daratumumab, bortezomib, and dexamethasone for multiple myeloma].

An 83-year-old man presented with visual disturbance and right hemiparalysis, one month after daratumumab, bortezomib, and dexamethasone administration for multiple myeloma (MM). Blood screens revealed a CD4+ T-lymphocyte count of 132/µl. Diffusion weighted and fluid-attenuated inversion-recovery MR imaging showed high intensity signals in the both occipital lobes and left precentral area. The patient had no history of human immunodeficiency virus infection. Cerebrospinal fluid (CSF) JC virus (JCV) was positive (83 copies/ml), as indicated by PCR. The patient was diagnosed with progressive multifocal leukoencephalopathy (PML). MM treatment was discontinued, and mefloquine and mirtazapine therapy was started. However, the CSF JCV-DNA PCR count did not improve (111 copies/ml) after 30 days from starting mefloquine and mirtazapine therapy. The patient died six months after symptom onset. Conclusively, patients with decreased CD4+ T lymphocyte counts following DBd therapy for MM, the possibility of PML should be considered.

Transition Metal Complexes as Antimalarial Agents: A Review.

In antimalarial drug development research, overcoming drug resistance has been a major challenge for researchers. Nowadays, several drugs like chloroquine, mefloquine, sulfadoxine, and artemisinin are used to treat malaria. But increment in drug resistance has pushed researchers to find novel drugs to tackle drug resistance problems. The idea of using transition metal complexes with pharmacophores as ligands/ligand pendants to show enhanced antimalarial activity with a novel mechanism of action has gained significant attention recently. The advantages of metal complexes include tunable chemical/physical properties, redox activity, avoiding resistance factors, etc. Several recent reports have successfully demonstrated that the metal complexation of known organic antimalarial drugs can overcome drug resistance by showing enhanced activities than the parent drugs. This review has discussed the fruitful research works done in the past few years falling into this criterion. Based on transition metal series (3d, 4d, or 5d), the antimalarial metal complexes have been divided into three broad categories (3d, 4d, or 5d metal-based), and their activities have been compared with the similar control complexes as well as the parent drugs. Furthermore, we have also commented on the potential issues and their possible solution for translating these metal-based antimalarial complexes into the clinic.

Neuropsychiatric Aspects of Parasitic Infections-A Review.

Neuropsychiatric disorders, ranging from mild cognitive impairment to frank psychosis, have been associated with certain parasitic infections. The parasite may cause damage to the central nervous system in several ways: as a space-occupying lesion (neuro-cysticercosis), alteration of neurotransmitters (toxoplasmosis), generation of the inflammatory response (trypanosomiasis, schistosomiasis), hypovolemic neuronal injury (cerebral malaria), or a combination of these. Certain drugs like quinacrine (mepacrine), mefloquine, quinolone, and interferon alpha which are used to treat these parasitic infections can further cause neuropsychiatric adverse effects. This review summarizes the major parasitic infections that are associated with neuropsychiatric disorders and the pathogenesis involved in their processes. A high index of suspicion for parasitic diseases, especially in endemic areas, should be kept in patients presenting with neuropsychiatric symptoms. A multidimensional approach to identification of the offending parasite using serological, radiological, and molecular tests is required not only to ensure proper and prompt treatment of the primary parasitic infection but also to improve the prognosis of patients by complete resolution of neuropsychiatric symptoms.

Hair concentrations of anti-malarials in returned travellers-the HAIR study: Proof of principle analysis.

BACKGROUND: Hair analysis to identify substance use is an established methodology. This could also be a method to monitor adherence to antimalarial drugs. We aimed to establish a methodology to determine hair concentrations of atovaquone, proguanil and mefloquine in travellers using chemoprophylaxis. METHODS: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous analysis of the antimalarial drugs -atovaquone (ATQ), proguanil (PRO) and mefloquine (MQ), in human hair. The hair samples from five volunteers were used for this proof-of-concept analysis. Three volunteers were taking daily atovaquone/proguanil (ATQ/PRO) chemoprophylaxis and two volunteers were using weekly mefloquine (MQ) chemoprophylaxis. RESULTS: With this proof-of-principle analysis, we could show that ATQ/PRO and MQ are integrated into the hair matrix. Chemoprophylaxis could be quantified with the established method. In hair segments, maximal concentrations of 3.0 ng/mL/20 mg hair proguanil, 1.3 ng/mL/20 mg hair atovaquone and 78.3 ng/mL/20 mg hair mefloquine were measured. Moreover, malaria drug concentration changes correlated with the time interval since finishing the chemoprophylaxis regimen. CONCLUSIONS: The validated method was used successfully for the analysis of antimalarial-drug positive hair samples containing atovaquone, proguanil or mefloquine. This research shows that hair can be used for adherence monitoring of chemoprophylaxis and paves the way for larger studies and optimized procedures.

Suspected Mefloquine Toxicity in a Colony of Humboldt Penguins (Spheniscus humboldti).

Avian malaria is an important cause of mortality in captive penguins housed in outdoor exhibits. Mefloquine was used as a prophylaxis to treat a colony of 19 Humboldt penguins (Spheniscus humboldti) for avian malaria. A target dose of 30 mg/kg was obtained from anecdotal literature for sphenisciforms that was not based on pharmacokinetic or toxicity studies. For this reason, preliminary plasma concentrations of mefloquine were acquired after the first dose in some penguins to ensure that plasma concentrations reached human malaria prophylactic concentrations. Afterward, each penguin in the entire colony received mefloquine (26-31 mg/kg [125 mg in toto] PO q7d). Regurgitation was frequently observed starting after the fourth weekly administration. Plasma concentrations of mefloquine after the seventh dose showed elevated concentrations, and the treatment was immediately terminated. Eight penguins died during and after the treatment period. The first fatality occurred after the fifth weekly administration, and 7 birds died within 7-52 days after the seventh weekly administration. Three penguins were found dead without previous symptoms. The other five presented with marked lethargy, dyspnea, poor appetite, and vomiting, and all died despite medical care. The remaining 11 penguins of the colony survived without any supportive care; 5 did not exhibit any clinical disease signs, while the other 6 showed a mild apathy and decreased appetite. Mefloquine toxicity was highly suspected on the basis of clinical signs, the elevated mefloquine plasma concentrations, and no other underlying pathologic disease conditions identified through postmortem examinations. Nonspecific lesions, including pulmonary congestion and edema and hepatic perivascular hematopoiesis, were noted in the birds that died. Additionally, 1 case presented with myocarditis, and mycobacteria were observed within granulomas in the respiratory tract of 2 penguins. Caution is advised, and further studies are encouraged before administering mefloquine to penguins.

Investigation of the mechanism of action of mefloquine and derivatives against the parasite Echinococcus multilocularis.

Alveolar echinococcosis (AE) is caused by infection with the fox tapeworm E. multilocularis. The disease affects humans, dogs, captive monkeys, and other mammals, and it is caused by the metacestode stage of the parasite growing invasively in the liver. The current drug treatment is based on non-parasiticidal benzimidazoles. Thus, they are only limitedly curative and can cause severe side effects. Therefore, novel and improved treatment options for AE are needed. Mefloquine (MEF), an antimalarial agent, was previously shown to be effective against E. multilocularis in vitro and in experimentally infected mice. However, MEF is not parasiticidal and needs improvement for successful treatment of patients, and it can induce strong neuropsychiatric side-effects. In this study, the structure-activity relationship and mode of action of MEF was investigated by comparative analysis of 14 MEF derivatives. None of them showed higher activity against E. multilocularis metacestodes compared to MEF, but four compounds caused limited damage. In order to identify molecular targets of MEF and effective derivatives, differential affinity chromatography combined with mass spectrometry was performed with two effective compounds (MEF, MEF-3) and two ineffective compounds (MEF-13, MEF-22). 1'681 proteins were identified that bound specifically to MEF or derivatives. 216 proteins were identified as binding only to MEF and MEF-3. GO term enrichment analysis of these proteins and functional grouping of the 25 most abundant MEF and MEF-3 specific binding proteins revealed the key processes energy metabolism and cellular transport and structure, as well as stress responses and nucleic acid binding to be involved. The previously described ferritin was confirmed as an exclusively MEF-binding protein that could be relevant for its efficacy against E. multilocularis. The here identified potential targets of MEF will be further investigated in the future for a clear understanding of the pleiotropic effects of MEF, and improved therapeutic options against AE.

Potential Anti-Mpox Virus Activity of Atovaquone, Mefloquine, and Molnupiravir, and Their Potential Use as Treatments.

BACKGROUND: Mpox virus (MPXV) is a zoonotic orthopoxvirus and caused an outbreak in 2022. Although tecovirimat and brincidofovir are approved as anti-smallpox drugs, their effects in mpox patients have not been well documented. In this study, by a drug repurposing approach, we identified potential drug candidates for treating mpox and predicted their clinical impacts by mathematical modeling. METHODS: We screened 132 approved drugs using an MPXV infection cell system. We quantified antiviral activities of potential drug candidates by measuring intracellular viral DNA and analyzed the modes of action by time-of-addition assay and electron microscopic analysis. We further predicted the efficacy of drugs under clinical concentrations by mathematical simulation and examined combination treatment. RESULTS: Atovaquone, mefloquine, and molnupiravir exhibited anti-MPXV activity, with 50% inhibitory concentrations of 0.51-5.2 µM, which was more potent than cidofovir. Whereas mefloquine was suggested to inhibit viral entry, atovaquone and molnupiravir targeted postentry processes. Atovaquone was suggested to exert its activity through inhibiting dihydroorotate dehydrogenase. Combining atovaquone with tecovirimat enhanced the anti-MPXV effect of tecovirimat. Quantitative mathematical simulations predicted that atovaquone can promote viral clearance in patients by 7 days at clinically relevant drug concentrations. CONCLUSIONS: These data suggest that atovaquone would be a potential candidate for treating mpox.