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Microbiology Spectrum Jun 2023The human malaria parasite undergoes a noncanonical cell division, namely, endoreduplication, where several rounds of nuclear, mitochondrial, and apicoplast replication...
The human malaria parasite undergoes a noncanonical cell division, namely, endoreduplication, where several rounds of nuclear, mitochondrial, and apicoplast replication occur without cytoplasmic division. Despite its importance in biology, the topoisomerases essential for decatenation of replicated chromosome during endoreduplication remain elusive. We hypothesize that the topoisomerase VI complex, containing Plasmodium falciparum topiosomerase VIB (PfTopoVIB) and catalytic P. falciparum Spo11 (PfSpo11), might be involved in the segregation of the mitochondrial genome. Here, we demonstrate that the putative PfSpo11 is the functional ortholog of yeast Spo11 that can complement the sporulation defects of the yeast Δ strain, and the catalytic mutant Pfspo11Y65F cannot complement such defects. PfTopoVIB and PfSpo11 display a distinct expression pattern compared to the other type II topoisomerases of and are induced specifically at the late schizont stage of the parasite, when the mitochondrial genome segregation occurs. Furthermore, PfTopoVIB and PfSpo11 are physically associated with each other at the late schizont stage, and both subunits are localized in the mitochondria. Using PfTopoVIB- and PfSpo11-specific antibodies, we immunoprecipitated the chromatin of tightly synchronous early, mid-, and late schizont stage-specific parasites and found that both the subunits are associated with the mitochondrial genome during the late schizont stage of the parasite. Furthermore, PfTopoVIB inhibitor radicicol and atovaquone show synergistic interaction. Accordingly, atovaquone-mediated disruption of mitochondrial membrane potential reduces the import and recruitment of both subunits of PfTopoVI to mitochondrial DNA (mtDNA) in a dose-dependent manner. The structural differences between PfTopoVIB and human TopoVIB-like protein could be exploited for development of a novel antimalarial agent. This study demonstrates a likely role of topoisomerase VI in the mitochondrial genome segregation of Plasmodium falciparum during endoreduplication. We show that PfTopoVIB and PfSpo11 remain associated and form the functional holoenzyme within the parasite. The spatiotemporal expression of both subunits of PfTopoVI correlates well with their recruitment to the mitochondrial DNA at the late schizont stage of the parasite. Additionally, the synergistic interaction between PfTopoVI inhibitor and the disruptor of mitochondrial membrane potential, atovaquone, supports that topoisomerase VI is the mitochondrial topoisomerase of the malaria parasite. We propose that topoisomerase VI may act as a novel target against malaria.
Topics: Animals; Humans; Parasites; Atovaquone; Saccharomyces cerevisiae; Plasmodium falciparum; Malaria, Falciparum; Malaria; DNA, Mitochondrial; Protozoan Proteins; Endodeoxyribonucleases; Saccharomyces cerevisiae Proteins
PubMed: 37212694
DOI: 10.1128/spectrum.04980-22 -
Patient Preference and Adherence 2020Chemoprophylaxis is an effective tool for individuals to minimize their risk of contracting malaria and serves an important public health role in preventing imported... (Review)
Review
BACKGROUND
Chemoprophylaxis is an effective tool for individuals to minimize their risk of contracting malaria and serves an important public health role in preventing imported malaria. Yet, it is only effective if the traveller is fully compliant with the prescribed regimen. For many destinations, a choice of prophylactic agents is available, so historical compliance data can be helpful for both physicians and travellers to make an informed decision.
METHODS
We analyzed the historical self-reported compliance data for six chemoprophylactic agents currently recommended by CDC for primary malaria chemoprophylaxis by searching PubMed, Embase, CINAHL, Web of Science, and Scopus for observational studies reporting on travelers within the last 25 years. The quality of data was graded as "good" or "poor" using the NIH quality assessment tool for cohort and cross-sectional studies. Cumulative compliance data were compiled for all studies (gross compliance) and the subgroup of studies with "good" quality evidence (refined compliance). Subgroup analyses were performed for weekly vs daily administered regimens, between military and civilian travelers, and across each prophylactic agent.
RESULTS
Twenty-four eligible studies assessed compliance for mefloquine (n=20), atovaquone-proguanil (n=11), doxycycline (n=13), and chloroquine (n=3). No studies were found for primaquine or tafenoquine. Both gross and refined compliance were significantly better for weekly regimens than daily regimens (<0.0001). Stopping chemoprophylaxis due to adverse events was significantly more for doxycycline (<0.0001) compared to other drugs. Compliance was significantly worse in military travelers, but they were also more likely to be prescribed doxycycline.
CONCLUSION
Malaria chemoprophylaxis for a traveler should depend on prevailing resistance patterns at destination, current national guidelines, and patient preferences. However, when there is a choice, historical compliance data are useful to select a regimen that the traveler is more likely to comply with.
PubMed: 33204072
DOI: 10.2147/PPA.S255561 -
Journal of Veterinary Internal Medicine Jul 2017Approximately one-third of dogs confiscated during dogfighting investigations are infected with Babesia gibsoni. Traditional management of B. gibsoni with polymerase... (Observational Study)
Observational Study
BACKGROUND
Approximately one-third of dogs confiscated during dogfighting investigations are infected with Babesia gibsoni. Traditional management of B. gibsoni with polymerase chain reaction (PCR)-screening, treatment with commercially available azithromycin and atovaquone, and PCR testing after 60 and 90 days is costly and impractical for large numbers of dogs at a time.
HYPOTHESIS/OBJECTIVES
To assess the efficacy of an alternative protocol in which commercial atovaquone was replaced by compounded medication and PCR monitoring was initiated at 30 days after the end of treatment to decrease the total management time.
METHODS
Prospective observational study. Forty-two pit bull-type dogs confiscated as part of an investigation of dogfighting, diagnosed with B. gibsoni infection, and judged to be suitable for adoption were treated with azithromycin (10 mg/kg PO q24h) and compounded atovaquone (13.4 mg/kg PO q8h with a fatty meal) for 10 days. PCR testing was repeated at 30 and 60 days after end of treatment if dogs with positive PCR tests at either time were tested at 90 days. Treatment was considered successful; 2 PCR tests 30 days apart were negative.
RESULTS
Treatment was successful in 39 dogs (93%) as defined by 2 consecutive PCR-negative test results 30 days apart. In 38 dogs (90%), PCR results were the same at 30 and 60 days.
CONCLUSIONS AND CLINICAL IMPORTANCE
Use of compounded atovaquone and a reduced monitoring period can reduce costs and holding times without compromising treatment efficacy. This more economical protocol can remove barriers to mass screening and management of B. gibsoni infections in dogfighting cases.
Topics: Animals; Antiprotozoal Agents; Atovaquone; Azithromycin; Babesia; Babesiosis; Dog Diseases; Dogs; Prospective Studies; Treatment Outcome
PubMed: 28625019
DOI: 10.1111/jvim.14777 -
Travel Medicine and Infectious Disease 2023Hair 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...
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.
Topics: Humans; Antimalarials; Proguanil; Atovaquone; Mefloquine; Chromatography, Liquid; Drug Therapy, Combination; Travel; Tandem Mass Spectrometry; Drug Combinations
PubMed: 37209974
DOI: 10.1016/j.tmaid.2023.102590 -
Data in Brief Dec 2022The dataset presented here is related to a previous research article titled "Mitochondrial Complex III in Larval Stage of as a Potential Chemotherapeutic Target and in...
The dataset presented here is related to a previous research article titled "Mitochondrial Complex III in Larval Stage of as a Potential Chemotherapeutic Target and in vivo Efficacy of Atovaquone Against Primary Hydatid Cysts"[1]. In this report, data were collected from aerobic and anaerobic culture assays of protoscoleces in the presence of three anti-echinococcal drug candidates (atovaquone, mefloquine, and 3-bromopyruvic acid). The data were analyzed for viability of the protoscoleces between day 0 and day 7 upon adding drug candidates. In aerobic condition, all drug candidates caused damage to the protoscoleces, as described previously [1], [2], [3], [4], [5], [6]. Mefloquine, alone as well as in combination with atovaquone, immediately eliminated the protoscoleces, whereas combination of atovaquone with 3-bromopyruvic acid did not show clear synergy. In anaerobic condition, mefloquine, alone as well as in combination with atovaquone, eliminated protoscoleces immediately. 3-Bromopyruvic acid showed stronger efficacy in anaerobic condition than in aerobic condition. Combination of atovaquone with 3-bromopyruvic acid eliminated the protoscoleces, indicating that synergy occurred only under anaerobic condition. The data clarified that combined use of the three drugs eliminated protoscoleces in both aerobic and anaerobic conditions, hence suggesting that these could inhibit aerobic and anaerobic respiration pathways of in vivo. The obtained data would be useful for the development of new drug dosing method for alveolar echinococcosis.
PubMed: 36426011
DOI: 10.1016/j.dib.2022.108707 -
Veterinary Sciences Jul 2022Differences in drug tolerability among vertebrate groups and species can create substantial challenges for wildlife and ex situ conservation programmes. Knowledge of...
Differences in drug tolerability among vertebrate groups and species can create substantial challenges for wildlife and ex situ conservation programmes. Knowledge of tolerance in the use of new drugs is, therefore, important to avoid severe toxicity in species, which are both commonly admitted in veterinary clinics and are of conservation concern. Antimalarial drugs have been developed for use in human medicine, but treatment with different agents has also long been used in avian medicine, as haemosporidian infections play a major role in many avian species. This study investigates the effects of the application of atovaquone-proguanil (Malarone, GlaxoSmithKline) in common buzzards (). The potential effects of treatment on body condition, growth rate, and chemical blood parameters of nestlings were assessed. All individuals survived the treatment, and no effects on body condition, growth rate, and chemical blood parameters were observed. Our results suggest the tolerability of Malarone in common buzzards at a single dose of on average 11 mg/kg body weight. For its safe use, we recommend further studies to determine pharmacokinetics in different avian species as well as to assess the effects of repeated treatment.
PubMed: 36006311
DOI: 10.3390/vetsci9080397 -
Frontiers in Microbiology 2014Toxoplasmosis is a major cause of foodborne disease, congenital complication, and morbidity. There is an urgent need for safe and effective therapies to encounter...
UNLABELLED
Toxoplasmosis is a major cause of foodborne disease, congenital complication, and morbidity. There is an urgent need for safe and effective therapies to encounter congenital and persisting toxoplasmosis. The hypothesis was: combination diclazuril plus atovaquone to exert a novel therapeutic synergy to prevent toxoplasmosis syndromes.
METHODS
Pregnant dams were treated with diclazuril and atovaquone monotherapy or combination therapy and infected i.p with Toxoplasma tachyzoites.
RESULTS
Infected dams developed severe toxoplasmosis associated syndrome with increases in the abdominal adiposity surrounding uteri, gansterointestinal and other internal organs and excessive weight gain. Numerous organisms along with infiltration of inflammatory cells were detected scattered into adipose tissues. Combination therapy (p < 0.01) and to a lesser extent diclazuril (p < 0.05) protected dams from inflammatory fat and excess weight gains. This was consistent with pancreatitis development in infected dams (versus normal p < 0.05) with infiltration of inflammatory cells, degeneration and necrosis of pancreatic cells followed by the degeneration and loss of islets. Combination and monotherapy protected dams from these inflammatory and pathological aspects of pancreatitis. Infected dams exhibited severe colitis, and colonic tissues significantly shortened in length. Brush border epithelial cells were replaced with infiltration of lymphocytes, granulocytes, and microabscess formations into cryptic microstructures. Combination therapy synergistically preserved colonic structure and normalized pathological damages (p < 0.001) and to a lesser degree diclazuril monotherapy protected dams from colitis (p < 0.05) and gastrointestinal toxoplasmosis. Other complications included severe splenitis (p < 0.001) and hepatitis (p < 0.001) which were normalized with combination therapy.
CONCLUSION
Combination diclazuril plus atovaquone was safe and with a novel therapeutic synergism protected dams and fetuses from toxoplasmosis.
PubMed: 25309522
DOI: 10.3389/fmicb.2014.00484 -
Pharmaceuticals (Basel, Switzerland) May 2021Triple-negative breast cancer (TNBC) is considered to be the most aggressive and malignant neoplasm and is highly metastatic in nature. In the current study, we...
Triple-negative breast cancer (TNBC) is considered to be the most aggressive and malignant neoplasm and is highly metastatic in nature. In the current study, we investigated the anti-metastatic potential of atovaquone, a protozoal drug prescribed for Pneumocystis pneumonia. We showed that atovaquone induced apoptosis and reduced the survival of several aggressive metastatic TNBC cell lines including metastatic patient-derived cells by reducing the expression of integrin α6, integrin β4, FAK, Src, and Vimentin. In order to study the efficacy of atovaquone in suppressing metastasized breast tumor cells in brain and lungs, we performed three in vivo experiments. We demonstrated that oral administration of 50 mg/kg of atovaquone suppressed MDA-MB-231 breast tumor growth by 90% in lungs in an intravenous metastatic tumor model. Anti-metastatic effect of atovaquone was further determined by intracardiac injection of 4T1-luc breast tumor cells into the left ventricle of mouse heart. Our results showed that atovaquone treatment suppressed the growth of metastatic tumors in lungs, liver and brain by 70%, 50% and 30% respectively. In an intracranial model, the growth of HCC1806-luc brain tumors in atovaquone treated mice was about 55% less than that of control. Taken together, our results indicate the anti-metastatic effects of atovaquone in vitro and in vivo in various breast tumor metastasis models.
PubMed: 34071408
DOI: 10.3390/ph14060521 -
Blood Advances Dec 2019Atovaquone, a US Food and Drug Administration-approved antiparasitic drug previously shown to reduce interleukin-6/STAT3 signaling in myeloma cells, is well tolerated,...
Atovaquone, a US Food and Drug Administration-approved antiparasitic drug previously shown to reduce interleukin-6/STAT3 signaling in myeloma cells, is well tolerated, and plasma concentrations of 40 to 80 µM have been achieved with pediatric and adult dosing. We conducted preclinical testing of atovaquone with acute myeloid leukemia (AML) cell lines and pediatric patient samples. Atovaquone induced apoptosis with an EC50 <30 µM for most AML lines and primary pediatric AML specimens. In NSG mice xenografted with luciferase-expressing THP-1 cells and in those receiving a patient-derived xenograft, atovaquone-treated mice demonstrated decreased disease burden and prolonged survival. To gain a better understanding of the mechanism of atovaquone, we performed an integrated analysis of gene expression changes occurring in cancer cell lines after atovaquone exposure. Atovaquone promoted phosphorylation of eIF2α, a key component of the integrated stress response and master regulator of protein translation. Increased levels of phosphorylated eIF2α led to greater abundance of the transcription factor ATF4 and its target genes, including proapoptotic CHOP and CHAC1. Furthermore, atovaquone upregulated REDD1, an ATF4 target gene and negative regulator of the mechanistic target of rapamycin (mTOR), and caused REDD1-mediated inhibition of mTOR activity with similar efficacy as rapamycin. Additionally, atovaquone suppressed the oxygen consumption rate of AML cells, which has specific implications for chemotherapy-resistant AML blasts that rely on oxidative phosphorylation for survival. Our results provide insight into the complex biological effects of atovaquone, highlighting its potential as an anticancer therapy with novel and diverse mechanisms of action, and support further clinical evaluation of atovaquone for pediatric and adult AML.
Topics: Activating Transcription Factor 4; Adolescent; Animals; Apoptosis; Atovaquone; Cell Line, Tumor; Cell Survival; Child; Child, Preschool; Disease Models, Animal; Female; Humans; Infant; Leukemia, Myeloid, Acute; Male; Mice; Mice, Knockout; Oxidative Phosphorylation; Signal Transduction; Xenograft Model Antitumor Assays
PubMed: 31856268
DOI: 10.1182/bloodadvances.2019000499 -
CMAJ : Canadian Medical Association... Aug 2021
Topics: Aged; Anemia; Anti-Infective Agents; Atovaquone; Azithromycin; Babesia microti; Babesiosis; Canada; Humans; Male; Thrombocytopenia; Treatment Outcome
PubMed: 34373269
DOI: 10.1503/cmaj.201983