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Fajtova P, Hurysz BM, Miyamoto Y, Serafim M, Jiang Z, Trujillo DF, Liu L, Somani U, Almaliti J, Myers SA, Caffrey CR, Gerwick WH, Kirk CJ, Boura E, Eckmann L, O'Donoghue AJ. Development of subunit selective substrates for Trichomonas vaginalis proteasome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.05.535794. [PMID: 37066163 PMCID: PMC10104049 DOI: 10.1101/2023.04.05.535794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
The protozoan parasite, Trichomonas vaginalis (Tv) causes trichomoniasis, the most common, non-viral, sexually transmitted infection in the world. Only two closely related drugs are approved for its treatment. The accelerating emergence of resistance to these drugs and lack of alternative treatment options poses an increasing threat to public health. There is an urgent need for novel effective anti-parasitic compounds. The proteasome is a critical enzyme for T. vaginalis survival and was validated as a drug target to treat trichomoniasis. However, to develop potent inhibitors of the T. vaginalis proteasome, it is essential that we understand which subunits should be targeted. Previously, we identified two fluorogenic substrates that were cleaved by T. vaginalis proteasome, however after isolating the enzyme complex and performing an in-depth substrate specificity study, we have now designed three fluorogenic reporter substrates that are each specific for one catalytic subunit. We screened a library of peptide epoxyketone inhibitors against the live parasite and evaluated which subunits are targeted by the top hits. Together we show that targeting of the β5 subunit of T. vaginalis is sufficient to kill the parasite, however, targeting of β5 plus either β1 or β2 results in improved potency.
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Huang PJ, Huang CY, Li YX, Liu YC, Chu LJ, Yeh YM, Cheng WH, Chen RM, Lee CC, Chen LC, Lin HC, Chiu SF, Lin WN, Lyu PC, Tang P, Huang KY. Dissecting the Transcriptomes of Multiple Metronidazole-Resistant and Sensitive Trichomonas vaginalis Strains Identified Distinct Genes and Pathways Associated with Drug Resistance and Cell Death. Biomedicines 2021; 9:biomedicines9121817. [PMID: 34944632 PMCID: PMC8698965 DOI: 10.3390/biomedicines9121817] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 12/20/2022] Open
Abstract
Trichomonas vaginalis is the causative agent of trichomoniasis, the most prevalent non-viral sexually transmitted infection worldwide. Metronidazole (MTZ) is the mainstay of anti-trichomonal chemotherapy; however, drug resistance has become an increasingly worrying issue. Additionally, the molecular events of MTZ-induced cell death in T. vaginalis remain elusive. To gain insight into the differential expression of genes related to MTZ resistance and cell death, we conducted RNA-sequencing of three paired MTZ-resistant (MTZ-R) and MTZ-sensitive (MTZ-S) T. vaginalis strains treated with or without MTZ. Comparative transcriptomes analysis identified that several putative drug-resistant genes were exclusively upregulated in different MTZ-R strains, such as ATP-binding cassette (ABC) transporters and multidrug resistance pumps. Additionally, several shared upregulated genes among all the MTZ-R transcriptomes were not previously identified in T. vaginalis, such as 5′-nucleotidase surE and Na+-driven multidrug efflux pump, which are a potential stress response protein and a multidrug and toxic compound extrusion (MATE)-like protein, respectively. Functional enrichment analysis revealed that purine and pyrimidine metabolisms were suppressed in MTZ-S parasites upon drug treatment, whereas the endoplasmic reticulum-associated degradation (ERAD) pathway, proteasome, and ubiquitin-mediated proteolysis were strikingly activated, highlighting the novel pathways responsible for drug-induced stress. Our work presents the most detailed analysis of the transcriptional changes and the regulatory networks associated with MTZ resistance and MTZ-induced signaling, providing insights into MTZ resistance and cell death mechanisms in trichomonads.
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Affiliation(s)
- Po-Jung Huang
- Department of Biomedical Sciences, Chang Gung University, Taoyuan City 333, Taiwan;
- Genomic Medicine Core Laboratory, Chang Gung Memorial Hospital, Linkou, Taoyuan City 333, Taiwan; (Y.-M.Y.); (C.-C.L.)
| | - Ching-Yun Huang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei City 114, Taiwan; (C.-Y.H.); (S.-F.C.)
- Host-Parasite Interactions Laboratory, National Defense Medical Center, Taipei City 114, Taiwan
| | - Yu-Xuan Li
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 333, Taiwan; (Y.-X.L.); (L.-J.C.); (P.T.)
| | - Yi-Chung Liu
- Institute of Bioinformatics and Structural Biology, Department of Life Science, National Tsing Hua University, Hsinchu 300, Taiwan; (Y.-C.L.); (P.-C.L.)
| | - Lichieh-Julie Chu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 333, Taiwan; (Y.-X.L.); (L.-J.C.); (P.T.)
- Molecular Medicine Research Center, Chang Gung University, Taoyuan City 333, Taiwan
- Liver Research Center, Chang Gung Memorial Hospital, Linkou, Taoyuan City 333, Taiwan
| | - Yuan-Ming Yeh
- Genomic Medicine Core Laboratory, Chang Gung Memorial Hospital, Linkou, Taoyuan City 333, Taiwan; (Y.-M.Y.); (C.-C.L.)
| | - Wei-Hung Cheng
- Department of Medical Laboratory Science, College of Medicine, I-Shou University, Kaohsiung City 824, Taiwan;
| | - Ruei-Ming Chen
- Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei City 114, Taiwan; (R.-M.C.); (H.-C.L.)
| | - Chi-Ching Lee
- Genomic Medicine Core Laboratory, Chang Gung Memorial Hospital, Linkou, Taoyuan City 333, Taiwan; (Y.-M.Y.); (C.-C.L.)
- Department of Computer Science and Information Engineering, Chang Gung University, Taoyuan City 333, Taiwan
| | - Lih-Chyang Chen
- Department of Medicine, Mackay Medical College, New Taipei City 252, Taiwan;
| | - Hsin-Chung Lin
- Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei City 114, Taiwan; (R.-M.C.); (H.-C.L.)
- Graduate Institute of Pathology and Parasitology, National Defense Medical Center, Taipei City 114, Taiwan
| | - Shu-Fang Chiu
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei City 114, Taiwan; (C.-Y.H.); (S.-F.C.)
- Host-Parasite Interactions Laboratory, National Defense Medical Center, Taipei City 114, Taiwan
- Department of Inspection, Taipei City Hospital, Renai Branch, Taipei City 114, Taiwan
| | - Wei-Ning Lin
- Graduate Institute of Biomedical and Pharmaceutical Science, Fu Jen Catholic University, New Taipei City 242, Taiwan;
| | - Ping-Chiang Lyu
- Institute of Bioinformatics and Structural Biology, Department of Life Science, National Tsing Hua University, Hsinchu 300, Taiwan; (Y.-C.L.); (P.-C.L.)
| | - Petrus Tang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City 333, Taiwan; (Y.-X.L.); (L.-J.C.); (P.T.)
| | - Kuo-Yang Huang
- Host-Parasite Interactions Laboratory, National Defense Medical Center, Taipei City 114, Taiwan
- Graduate Institute of Pathology and Parasitology, National Defense Medical Center, Taipei City 114, Taiwan
- Correspondence: ; Tel.: +886-2-87923100 (ext. 18564)
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Natto MJ, Miyamoto Y, Munday JC, AlSiari TA, Al-Salabi MI, Quashie NB, Eze AA, Eckmann L, De Koning HP. Comprehensive characterization of purine and pyrimidine transport activities in Trichomonas vaginalis and functional cloning of a trichomonad nucleoside transporter. Mol Microbiol 2021; 116:1489-1511. [PMID: 34738285 PMCID: PMC8688338 DOI: 10.1111/mmi.14840] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/30/2021] [Accepted: 10/30/2021] [Indexed: 11/30/2022]
Abstract
Trichomoniasis is a common and widespread sexually-transmitted infection, caused by the protozoan parasite Trichomonas vaginalis. T. vaginalis lacks the biosynthetic pathways for purines and pyrimidines, making nucleoside metabolism a drug target. Here we report the first comprehensive investigation into purine and pyrimidine uptake by T. vaginalis. Multiple carriers were identified and characterized with regard to substrate selectivity and affinity. For nucleobases, a high-affinity adenine transporter, a possible guanine transporter and a low affinity uracil transporter were found. Nucleoside transporters included two high affinity adenosine/guanosine/uridine/cytidine transporters distinguished by different affinities to inosine, a lower affinity adenosine transporter, and a thymidine transporter. Nine Equilibrative Nucleoside Transporter (ENT) genes were identified in the T. vaginalis genome. All were expressed equally in metronidazole-resistant and -sensitive strains. Only TvagENT2 was significantly upregulated in the presence of extracellular purines; expression was not affected by co-culture with human cervical epithelial cells. All TvagENTs were cloned and separately expressed in Trypanosoma brucei. We identified the main broad specificity nucleoside carrier, with high affinity for uridine and cytidine as well as purine nucleosides including inosine, as TvagENT3. The in-depth characterization of purine and pyrimidine transporters provides a critical foundation for the development of new anti-trichomonal nucleoside analogues.
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Affiliation(s)
- Manal J. Natto
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Yukiko Miyamoto
- Department of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jane C. Munday
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Tahani A. AlSiari
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Mohammed I. Al-Salabi
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Neils B. Quashie
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Centre for Tropical Clinical Pharmacology and Therapeutics, University of Ghana Medical School, University of Ghana
| | - Anthonius A. Eze
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
- Current affiliation: Department of Medical Biochemistry, Faculty of Basic Medical Sciences, College of Medicine, University of Nigeria, Enugu Campus, Enugu, Nigeria
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Harry P. De Koning
- Institute of Infection, Immunity and Inflammation, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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Miyamoto Y, Aggarwal S, Celaje JJA, Ihara S, Ang J, Eremin DB, Land KM, Wrischnik LA, Zhang L, Fokin VV, Eckmann L. Gold(I) Phosphine Derivatives with Improved Selectivity as Topically Active Drug Leads to Overcome 5-Nitroheterocyclic Drug Resistance in Trichomonas vaginalis. J Med Chem 2021; 64:6608-6620. [PMID: 33974434 DOI: 10.1021/acs.jmedchem.0c01926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Trichomonas vaginalis causes the most common, nonviral sexually transmitted infection. Only metronidazole (Mz) and tinidazole are approved for treating trichomoniasis, yet resistance is a clinical problem. The gold(I) complex, auranofin, is active against T. vaginalis and other protozoa but has significant human toxicity. In a systematic structure-activity exploration, we show here that diversification of gold(I) complexes, particularly as halides with simple C1-C3 trialkyl phosphines or as bistrialkyl phosphine complexes, can markedly improve potency against T. vaginalis and selectivity over human cells compared to that of the existing antirheumatic gold(I) drugs. All gold(I) complexes inhibited the two most abundant isoforms of the presumed target enzyme, thioredoxin reductase, but a subset of compounds were markedly more active against live T. vaginalis than the enzyme, suggesting that alternative targets exist. Furthermore, all tested gold(I) complexes acted independently of Mz and were able to overcome Mz resistance, making them candidates for the treatment of Mz-refractory trichomoniasis.
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Affiliation(s)
- Yukiko Miyamoto
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Shubhangi Aggarwal
- Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Jeff Joseph A Celaje
- Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Sozaburo Ihara
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Jonathan Ang
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Dmitry B Eremin
- Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Kirkwood M Land
- Department of Biological Sciences, University of the Pacific, Stockton, California 95211, United States
| | - Lisa A Wrischnik
- Department of Biological Sciences, University of the Pacific, Stockton, California 95211, United States
| | - Liangfang Zhang
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Valery V Fokin
- Department of Chemistry, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Lars Eckmann
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
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A systematic review of the literature on mechanisms of 5-nitroimidazole resistance in Trichomonas vaginalis. Parasitology 2020; 147:1383-1391. [PMID: 32729451 DOI: 10.1017/s0031182020001237] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Trichomonas vaginalis is the most common non-viral sexually transmitted infection. 5-Nitroimidazoles [metronidazole (MTZ) and tinidazole (TDZ)] are FDA-approved treatments. To better understand treatment failure, we conducted a systematic review on mechanisms of 5-nitroimidazole resistance. METHODS PubMed, ScienceDirect and EMBASE databases were searched using keywords Trichomonas vaginalis, trichomoniasis, 5-nitroimidazole, metronidazole, tinidazole and drug resistance. Non-English language articles and articles on other treatments were excluded. RESULTS The search yielded 606 articles, of which 550 were excluded, leaving 58 articles. Trichomonas vaginalis resistance varies and is higher with MTZ (2.2-9.6%) than TDZ (0-2%). Resistance can be aerobic or anaerobic and is relative rather than absolute. Differential expression of enzymes involved in trichomonad energy production and antioxidant defenses affects 5-nitroimidazole drug activation; reduced expression of pyruvate:ferredoxin oxidoreductase, ferredoxin, nitroreductase, hydrogenase, thioredoxin reductase and flavin reductase are implicated in drug resistance. Trichomonas vaginalis infection with Mycoplasma hominis or T. vaginalis virus has also been associated with resistance. Trichomonas vaginalis has two genotypes, with greater resistance seen in type 2 (vs type 1) populations. DISCUSSION 5-Nitroimidazole resistance results from differential expression of enzymes involved in energy production or antioxidant defenses, along with genetic mutations in the T. vaginalis genome. Alternative treatments outside of the 5-nitroimidazole class are needed.
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20S Proteasome as a Drug Target in Trichomonas vaginalis. Antimicrob Agents Chemother 2019; 63:AAC.00448-19. [PMID: 31451503 DOI: 10.1128/aac.00448-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 08/19/2019] [Indexed: 12/17/2022] Open
Abstract
Trichomoniasis is a sexually transmitted disease with hundreds of millions of annual cases worldwide. Approved treatment options are limited to two related nitro-heterocyclic compounds, yet resistance to these drugs is an increasing concern. New antimicrobials against the causative agent, Trichomonas vaginalis, are urgently needed. We show here that clinically approved anticancer drugs that inhibit the proteasome, a large protease complex with a critical role in degrading intracellular proteins in eukaryotes, have submicromolar activity against the parasite in vitro and on-target activity against the enriched T. vaginalis proteasome in cell-free assays. Proteomic analysis confirmed that the parasite has all seven α and seven β subunits of the eukaryotic proteasome although they have only modest sequence identities, ranging from 28 to 52%, relative to the respective human proteasome subunits. A screen of proteasome inhibitors derived from a marine natural product, carmaphycin, revealed one derivative, carmaphycin-17, with greater activity against T. vaginalis than the reference drug metronidazole, the ability to overcome metronidazole resistance, and reduced human cytotoxicity compared to that of the anticancer proteasome inhibitors. The increased selectivity of carmaphycin-17 for T. vaginalis was related to its >5-fold greater potency against the β1 and β5 catalytic subunits of the T. vaginalis proteasome than against the human proteasome subunits. In a murine model of vaginal trichomonad infection, proteasome inhibitors eliminated or significantly reduced parasite burden upon topical treatment without any apparent adverse effects. Together, these findings validate the proteasome of T. vaginalis as a therapeutic target for development of a novel class of trichomonacidal agents.
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Bradic M, Warring SD, Tooley GE, Scheid P, Secor WE, Land KM, Huang PJ, Chen TW, Lee CC, Tang P, Sullivan SA, Carlton JM. Genetic Indicators of Drug Resistance in the Highly Repetitive Genome of Trichomonas vaginalis. Genome Biol Evol 2018. [PMID: 28633446 PMCID: PMC5522705 DOI: 10.1093/gbe/evx110] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Trichomonas vaginalis, the most common nonviral sexually transmitted parasite, causes ∼283 million trichomoniasis infections annually and is associated with pregnancy complications and increased risk of HIV-1 acquisition. The antimicrobial drug metronidazole is used for treatment, but in a fraction of clinical cases, the parasites can become resistant to this drug. We undertook sequencing of multiple clinical isolates and lab derived lines to identify genetic markers and mechanisms of metronidazole resistance. Reduced representation genome sequencing of ∼100 T. vaginalis clinical isolates identified 3,923 SNP markers and presence of a bipartite population structure. Linkage disequilibrium was found to decay rapidly, suggesting genome-wide recombination and the feasibility of genetic association studies in the parasite. We identified 72 SNPs associated with metronidazole resistance, and a comparison of SNPs within several lab-derived resistant lines revealed an overlap with the clinically resistant isolates. We identified SNPs in genes for which no function has yet been assigned, as well as in functionally-characterized genes relevant to drug resistance (e.g., pyruvate:ferredoxin oxidoreductase). Transcription profiles of resistant strains showed common changes in genes involved in drug activation (e.g., flavin reductase), accumulation (e.g., multidrug resistance pump), and detoxification (e.g., nitroreductase). Finally, we identified convergent genetic changes in lab-derived resistant lines of Tritrichomonas foetus, a distantly related species that causes venereal disease in cattle. Shared genetic changes within and between T. vaginalis and Tr. foetus parasites suggest conservation of the pathways through which adaptation has occurred. These findings extend our knowledge of drug resistance in the parasite, providing a panel of markers that can be used as a diagnostic tool.
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Affiliation(s)
- Martina Bradic
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
| | - Sally D Warring
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
| | - Grace E Tooley
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
| | - Paul Scheid
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
| | - William E Secor
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GE
| | - Kirkwood M Land
- Department of Biological Sciences, University of the Pacific, Stockton, CA
| | - Po-Jung Huang
- Bioinformatics Center/Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Ting-Wen Chen
- Bioinformatics Center/Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Chi-Ching Lee
- Bioinformatics Center/Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Petrus Tang
- Bioinformatics Center/Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan
| | - Steven A Sullivan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
| | - Jane M Carlton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York
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Chlorinated metronidazole as a promising alternative for treating trichomoniasis. Parasitol Res 2018; 117:1333-1340. [PMID: 29502297 DOI: 10.1007/s00436-018-5813-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 02/15/2018] [Indexed: 12/11/2022]
Abstract
Trichomoniasis is the most common non-viral, sexually transmitted infection affecting humans worldwide. The main treatment for trichomoniasis is metronidazole (MTZ). However, adverse effects and reports of resistance have stimulated the development of therapeutic alternatives. The ease of manipulation of the side chains of MTZ coupled with its safety makes this molecule attractive for the development of new drugs. In this context, we evaluated the activity of the chlorinated MTZ derivative, MTZ-Cl, on sensitive and resistant strains of Trichomonas vaginalis. MTZ-Cl presented a remarkable activity against both sensitive and resistant strains. In vitro and in vivo toxicity assays indicated that the new molecule is safe for future clinical trials. Furthermore, we noticed different rates of free radical production between the sensitive and resistant strains. MTZ-Cl induced a higher release of nitric oxide (NO, ~ 9000 a.u.) by both sensitive and resistant strains. However, the sensitive strain produced a greater amount of H2O2 (~ 1,800,000 a.u.) and superoxide radicals (~ 350,000 a.u.) in the presence of MTZ. In the resistant strain, production of these radicals was more prominent when MTZ-Cl was used. Collectively, these results suggest that NO is an important molecule in the trichomonacidal activity against resistant and sensitive strains, suggesting an alternative pathway for MTZ-Cl activation. We highlight the high trichomonacidal potential of MTZ-Cl, improving the effectiveness of treatment and reducing side effects. In addition, MTZ-Cl is derived from a well-established drug on the world market that presents low toxicity to human cells, suggesting its safety to proceed with future clinical trials.
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Ang CW, Jarrad AM, Cooper MA, Blaskovich MAT. Nitroimidazoles: Molecular Fireworks That Combat a Broad Spectrum of Infectious Diseases. J Med Chem 2017; 60:7636-7657. [PMID: 28463485 DOI: 10.1021/acs.jmedchem.7b00143] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Infectious diseases claim millions of lives every year, but with the advent of drug resistance, therapeutic options to treat infections are inadequate. There is now an urgent need to develop new and effective treatments. Nitroimidazoles are a class of antimicrobial drugs that have remarkable broad spectrum activity against parasites, mycobacteria, and anaerobic Gram-positive and Gram-negative bacteria. While nitroimidazoles were discovered in the 1950s, there has been renewed interest in their therapeutic potential, particularly for the treatment of parasitic infections and tuberculosis. In this review, we summarize different classes of nitroimidazoles that have been described in the literature in the past five years, from approved drugs and clinical candidates to examples undergoing preclinical or early stage development. The relatively "nonspecific" mode of action and resistance mechanisms of nitromidazoles are discussed, and contemporary strategies to facilitate nitroimidazole drug development are highlighted.
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Affiliation(s)
- Chee Wei Ang
- The Institute for Molecular Bioscience, The University of Queensland , St Lucia, Queensland 4072, Australia
| | - Angie M Jarrad
- The Institute for Molecular Bioscience, The University of Queensland , St Lucia, Queensland 4072, Australia
| | - Matthew A Cooper
- The Institute for Molecular Bioscience, The University of Queensland , St Lucia, Queensland 4072, Australia
| | - Mark A T Blaskovich
- The Institute for Molecular Bioscience, The University of Queensland , St Lucia, Queensland 4072, Australia
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10
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An improved quantitative method to assess adhesive properties of Trichomonas vaginalis to host vaginal ectocervical cells using flow cytometry. J Microbiol Methods 2012; 92:73-8. [PMID: 23142340 DOI: 10.1016/j.mimet.2012.10.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 10/26/2012] [Accepted: 10/26/2012] [Indexed: 11/20/2022]
Abstract
Microbial adhesion is a critical step for infection and colonization of the host. Trichomonas vaginalis, a human urogenital extracellular parasite, relies on host cell adhesion for infection and pathogenesis. Although host cell adhesion of T. vaginalis is strain-dependent and it may be influenced by many environmental factors, a technical limitation to quantify T. vaginalis adhesion falls upon a laborious and time-consuming protocol of fluorescent microscopy. This technical limitation reduces the ability of screening multiple parameters or detecting multiple cell types simultaneously. Here we tested the capability of using flow cytometry as a qualitative and quantitative method to measure adhesion of this human infectious microorganism to vaginal ectocervical cells. Various strains of T. vaginalis with different adhesion properties were stained with CellTracker Orange (CMTMR) prior to incubation with host cells. Analyses by flow cytometry revealed that adhered CMTMR-stained parasites were clearly distinguishable from the host cells and also enabled absolute cell counts to be determined. This method was validated with the comparison of parasite strains that display variable degrees of host cell adhesion. This assay can now be applied to test many variables and environmental factors simultaneously that may affect T. vaginalis adhesion.
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11
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Nagata N, Marriott D, Harkness J, Ellis JT, Stark D. Current treatment options for Dientamoeba fragilis infections. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2012; 2:204-15. [PMID: 24533282 DOI: 10.1016/j.ijpddr.2012.08.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/06/2012] [Accepted: 08/07/2012] [Indexed: 12/20/2022]
Abstract
Dientamoeba fragilis belongs to the trichomonad group of protozoan parasites and it has been implicated as a cause of gastrointestinal disease with world-wide prevalences ranging from 0.5% to 16%. The majority of patients with dientamoebiasis present with gastrointestinal complaints. Chronic symptoms are common with up to a third of patients exhibiting persistent diarrhoea. Numerous studies have successfully demonstrated parasite clearance, coupled with complete resolution of clinical symptoms following treatment with various antiparasitic compounds. Treatments reported to be successful for dientamoebiasis include carbarsone, diphetarsone, tetracyclines, paromomycin, erythromycin, hydroxyquinolines and the 5-nitroimidazoles, including metronidazole, secnidazole, tinidazole and ornidazole. It is of note that most current treatment data is based only on small number of case reports. No large scale double blind randomised placebo controlled trials testing the efficacy of antimicrobial agents against D. fragilis has been undertaken highlighting the need for further study. In addition there is very little in vitro susceptibility data available for the organism making some current treatment options questionable. The aim of this review is to critically discuss all treatment options currently available for dientamoebiasis.
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Affiliation(s)
- Noriyuki Nagata
- Division of Microbiology, SydPath, St. Vincent's Hospital, Darlinghurst, Australia ; University of Technology Sydney, School of Medical and Molecular Biosciences, Broadway, Australia
| | - Deborah Marriott
- Division of Microbiology, SydPath, St. Vincent's Hospital, Darlinghurst, Australia ; University of Technology Sydney, School of Medical and Molecular Biosciences, Broadway, Australia
| | - John Harkness
- Division of Microbiology, SydPath, St. Vincent's Hospital, Darlinghurst, Australia ; University of Technology Sydney, School of Medical and Molecular Biosciences, Broadway, Australia
| | - John T Ellis
- University of Technology Sydney, School of Medical and Molecular Biosciences, Broadway, Australia ; University of Technology Sydney, iThree Institute, Broadway, Australia
| | - Damien Stark
- Division of Microbiology, SydPath, St. Vincent's Hospital, Darlinghurst, Australia ; University of Technology Sydney, School of Medical and Molecular Biosciences, Broadway, Australia
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12
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Zedníková V, Beltrán NC, Tachezy J, Hrdý I. Alternative 2-keto acid oxidoreductases in Trichomonas vaginalis: Artifact of histochemical staining. Mol Biochem Parasitol 2012; 181:57-9. [DOI: 10.1016/j.molbiopara.2011.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 11/26/2022]
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Conrad M, Zubacova Z, Dunn LA, Upcroft J, Sullivan SA, Tachezy J, Carlton JM. Microsatellite polymorphism in the sexually transmitted human pathogen Trichomonas vaginalis indicates a genetically diverse parasite. Mol Biochem Parasitol 2010; 175:30-8. [PMID: 20813140 DOI: 10.1016/j.molbiopara.2010.08.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 08/19/2010] [Accepted: 08/23/2010] [Indexed: 10/19/2022]
Abstract
Given the growing appreciation of serious health sequelae from widespread Trichomonas vaginalis infection, new tools are needed to study the parasite's genetic diversity. To this end we have identified and characterized a panel of 21 microsatellites and six single-copy genes from the T. vaginalis genome, using seven laboratory strains of diverse origin. We have (1) adapted our microsatellite typing method to incorporate affordable fluorescent labeling, (2) determined that the microsatellite loci remain stable in parasites continuously cultured for up to 17 months, and (3) evaluated microsatellite marker coverage of the six chromosomes that comprise the T. vaginalis genome, using fluorescent in situ hybridization (FISH). We have used the markers to show that T. vaginalis is a genetically diverse parasite in a population of commonly used laboratory strains. In addition, we have used phylogenetic methods to infer evolutionary relationships from our markers in order to validate their utility in future population analyses. Our panel is the first series of robust polymorphic genetic markers for T. vaginalis that can be used to classify and monitor lab strains, as well as provide a means to measure the genetic diversity and population structure of extant and future T. vaginalis isolates.
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Affiliation(s)
- Melissa Conrad
- Department of Medical Parasitology, New York University Langone Medical Center, New York, NY 10010, USA
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Pineda E, Encalada R, Rodríguez-Zavala JS, Olivos-García A, Moreno-Sánchez R, Saavedra E. Pyruvate:ferredoxin oxidoreductase and bifunctional aldehyde-alcohol dehydrogenase are essential for energy metabolism under oxidative stress in Entamoeba histolytica. FEBS J 2010; 277:3382-95. [DOI: 10.1111/j.1742-4658.2010.07743.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Wright JM, Dunn LA, Kazimierczuk Z, Burgess AG, Krauer KG, Upcroft P, Upcroft JA. Susceptibility in vitro of clinically metronidazole-resistant Trichomonas vaginalis to nitazoxanide, toyocamycin, and 2-fluoro-2′-deoxyadenosine. Parasitol Res 2010; 107:847-53. [DOI: 10.1007/s00436-010-1938-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 05/26/2010] [Indexed: 11/28/2022]
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Leitsch D, Kolarich D, Duchêne M. The flavin inhibitor diphenyleneiodonium renders Trichomonas vaginalis resistant to metronidazole, inhibits thioredoxin reductase and flavin reductase, and shuts off hydrogenosomal enzymatic pathways. Mol Biochem Parasitol 2010; 171:17-24. [PMID: 20093143 DOI: 10.1016/j.molbiopara.2010.01.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 01/10/2010] [Accepted: 01/12/2010] [Indexed: 11/25/2022]
Abstract
Infections with the microaerophilic protozoan parasite Trichomonas vaginalis are commonly treated with metronidazole, a 5-nitroimidazole drug. Metronidazole is selectively toxic to microaerophiles and anaerobes because reduction at the drug's nitro group, which is a precondition for toxicity, occurs only quantitatively in these organisms. In our previous work we identified the flavin enzyme thioredoxin reductase as an electron donor to 5-nitroimidazole drugs in T. vaginalis and observed that highly metronidazole-resistant cell lines lack thioredoxin reductase and flavin reductase activities. In this study we added the flavin inhibitor diphenyleneiodonium (DPI) to T. vaginalis cultures in order to test our hypothesis that metronidazole reduction is catalyzed by flavin enzymes, e.g. thioredoxin reductase, and intracellular free flavins. Indeed, within hours, DPI rendered T. vaginalis insensitive to metronidazole concentrations as high as 1mM and prevented the formation of metronidazole adducts with proteins. Thioredoxin reductase activity was absent from DPI-treated cells and flavin reductase activity was sharply decreased. In addition, DPI-treated cells also upregulated the expression of antioxidant enzymes, i.e. thioredoxin peroxidases and superoxide dismutases, and displayed a fundamentally altered metabolism caused by inactivation of pyruvate:ferredoxin oxidoreductase (PFOR) and concomitant upregulation of lactate dehydrogenase (LDH) activity. Thus, the disruption of the cellular flavin metabolism by DPI mediated metabolic steps which are similar to that of cells with metronidazole resistance induced in vitro. Finally, we present direct evidence that the increased expression of antioxidant enzymes is dispensable for acquiring resistance to metronidazole.
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Affiliation(s)
- David Leitsch
- Department of Specific Prophylaxis and Tropical Medicine at the Center for Physiology, Pathophysiology and Immunology, Medical University of Vienna, A-1090 Vienna, Austria.
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Wright JM, Webb RI, O'Donoghue P, Upcroft P, Upcroft JA. Hydrogenosomes of laboratory-induced metronidazole-resistant Trichomonas vaginalis lines are downsized while those from clinically metronidazole-resistant isolates are not. J Eukaryot Microbiol 2009; 57:171-6. [PMID: 20015182 DOI: 10.1111/j.1550-7408.2009.00455.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Trichomonas vaginalis is the most common sexually transmitted protozoan in the world and its resistance to metronidazole is increasing. The purpose of this study was to demonstrate that clinical metronidazole resistance in T. vaginalis does not occur via the same mechanism as laboratory-induced metronidazole resistance--that is, via hydrogenosome down sizing. Ultrathin sections of this parasite were examined using transmission electron microscopy and the size and area of the cell and hydrogenosomes were compared between drug-resistant laboratory lines and clinically resistant isolates. Clinical metronidazole-resistant T. vaginalis had similar-sized hydrogenosomes as a metronidazole-sensitive isolate. Inducing metronidazole resistance in both of these isolates caused down sizing of hydrogenosomes. Inducing toyocamycin resistance did not cause any ultrastructural changes to the cell or to the hydrogenosome. No correlation between hydrogenosome number and the drug-resistant status of T. vaginalis isolates and lines was observed. This report demonstrates that clinical metronidazole resistance is not associated with down-sized hydrogenosomes, thus indicating that an alternative resistance mechanism is used by T. vaginalis.
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Affiliation(s)
- Janelle M Wright
- Queensland Institute of Medical Research, Brisbane, Queensland 4029, Australia.
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18
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Gehrig S, Efferth T. Development of Drug Resistance in Trichomonas vaginalis and its Overcoming with Natural Products. ACTA ACUST UNITED AC 2009. [DOI: 10.2174/1874847300902010021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trichomoniasis is an infectious disease afflicting women worldwide. The protozoan parasite Trichomonas vaginalis is the causative agent of this sexually-transmitted disease, including also men in its infection cycle. The disease is usually not life-threatening, but has been associated with the development of cervical cancer and increased susceptibility to HIV. Approved drugs are 5-nitroimidazoles, with metronidazole being the drug of first choice. These drugs act via induction of oxidative stress and DNA-damage, leading to cell death in the parasite. Nevertheless, with the development of resistant T. vaginalis strains the treatment of the disease becomes exceedingly difficult. Mechanisms of drug resistance are characterized by reduced expression or even loss of proteins necessary for drug activation and a decreased reductive nature in the parasite. A promising strategy for research into new drugs and moreover, to overcome drug resistance, are compounds derived from natural sources. The present study provides a summary of all so far investigated small molecules with antitrichomonal activity; promisingly, some also show efficacy against resistant strains. Whereas the list of chemically characterized compounds derived from plants is rather short, literature provides immense applications of crude plant extracts tested against T. vaginalis. This demonstrates the absence of studies in this field aimed to identify and isolate single natural products exhibiting antitrichomonal features. Likewise, elucidating their mode of action on a molecular basis is of paramount importance
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Current and future perspectives on the chemotherapy of the parasitic protozoa Trichomonas vaginalis and Entamoeba histolytica. Future Med Chem 2009; 1:619-43. [DOI: 10.4155/fmc.09.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Trichomonas vaginalis and Entamoeba histolytica are clinically important protozoa that affect humans. T. vaginalis produces sexually transmitted infections and E. histolytica is the causative agent of amebic dysentery. Metronidazole, a compound first used to treat T. vaginalis in 1959, is still the main drug used worldwide to treat these pathogens. It is essential to find new biochemical differences in these organisms that could be exploited to develop new antiprotozoal chemotherapeutics. Recent findings associated with T. vaginalis and E. histolytica biochemistry and host–pathogen interactions are surveyed. Knowledge concerning the biochemistry of these parasites is serving to form the foundation for the development of new approaches to control these important human pathogens.
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Leitsch D, Kolarich D, Binder M, Stadlmann J, Altmann F, Duchêne M. Trichomonas vaginalis: metronidazole and other nitroimidazole drugs are reduced by the flavin enzyme thioredoxin reductase and disrupt the cellular redox system. Implications for nitroimidazole toxicity and resistance. Mol Microbiol 2009; 72:518-36. [PMID: 19415801 DOI: 10.1111/j.1365-2958.2009.06675.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Infections with the microaerophilic parasite Trichomonas vaginalis are treated with the 5-nitroimidazole drug metronidazole, which is also in use against Entamoeba histolytica, Giardia intestinalis and microaerophilic/anaerobic bacteria. Here we report that in T. vaginalis the flavin enzyme thioredoxin reductase displays nitroreductase activity with nitroimidazoles, including metronidazole, and with the nitrofuran drug furazolidone. Reactive metabolites of metronidazole and other nitroimidazoles form covalent adducts with several proteins that are known or assumed to be associated with thioredoxin-mediated redox regulation, including thioredoxin reductase itself, ribonucleotide reductase, thioredoxin peroxidase and cytosolic malate dehydrogenase. Disulphide reducing activity of thioredoxin reductase was greatly diminished in extracts of metronidazole-treated cells and intracellular non-protein thiol levels were sharply decreased. We generated a highly metronidazole-resistant cell line that displayed only minimal thioredoxin reductase activity, not due to diminished expression of the enzyme but due to the lack of its FAD cofactor. Reduction of free flavins, readily observed in metronidazole-susceptible cells, was also absent in the resistant cells. On the other hand, iron-depleted T. vaginalis cells, expressing only minimal amounts of PFOR and hydrogenosomal malate dehydrogenase, remained fully susceptible to metronidazole. Thus, taken together, our data suggest a flavin-based mechanism of metronidazole activation and thereby challenge the current model of hydrogenosomal activation of nitroimidazole drugs.
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Affiliation(s)
- David Leitsch
- Department of Specific Prophylaxis and Tropical Medicine at the Center for Physiology, Pathophysiology and Immunology, Medical University of Vienna, Vienna, Austria.
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Rivera-Borroto O, Marrero-Ponce Y, Meneses-Marcel A, Escario J, Gómez Barrio A, Arán V, Martins Alho M, Montero Pereira D, Nogal J, Torrens F, Ibarra-Velarde F, Montenegro Y, Huesca-Guillén A, Rivera N, Vogel C. Discovery of Novel Trichomonacidals Using LDA-Driven QSAR Models and Bond-Based Bilinear Indices as Molecular Descriptors. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/qsar.200610165] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Antisense RNA decreases AP33 gene expression and cytoadherence by T. vaginalis. BMC Microbiol 2007; 7:64. [PMID: 17608941 PMCID: PMC1929106 DOI: 10.1186/1471-2180-7-64] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 07/03/2007] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Host parasitism by Trichomonas vaginalis is complex. Adherence to vaginal epithelial cells (VECs) is mediated by surface proteins. We showed before that antisense down-regulation of expression of adhesin AP65 decreased amounts of protein, which lowered levels of T. vaginalis adherence to VECs. We now perform antisense down-regulation of expression of the ap33 gene to evaluate and confirm a role for AP33 in adherence by T. vaginalis. We also used an established transfection system for heterologous expression of AP33 in T. foetus as an additional confirmatory approach. RESULTS We successfully select stable trichomonads with sense (S) and antisense (AS) plasmids. RT-PCR confirmed decreased amounts of ap33 mRNA in AS-transfected parasites, and decreased amounts of AP33 had no effect on growth and viability when compared to wild-type (wt) trichomonads. Immunoblots of proteins from AS-transfectants gave significant decreased amounts of functional AP33 capable of binding to host cells compared to wt- and S-transfected trichomonads. As expected, AS-transfectants had lower levels of adherence to VECs, which was related to reduction in surface expression of AP33. Stable expression of T. vaginalis AP33::HA fusion in T. foetus was confirmed by immunoblots and fluorescence. The episomally-expressed surface AP33::HA fusion increased adherence of trichomonads to human VECs, which was abrogated with anti-AP33 serum. CONCLUSION These results using both antisense inhibition of gene expression and AP33 synthesis and the heterologous expression of AP33 in T. foetus confirms a role for this protein as an adhesin in T. vaginalis.
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Rinaldo-Matthis A, Wing C, Ghanem M, Deng H, Wu P, Gupta A, Tyler PC, Evans GB, Furneaux RH, Almo SC, Wang CC, Schramm VL. Inhibition and structure of Trichomonas vaginalis purine nucleoside phosphorylase with picomolar transition state analogues. Biochemistry 2007; 46:659-68. [PMID: 17223688 PMCID: PMC2517847 DOI: 10.1021/bi061515r] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Trichomonas vaginalis is a parasitic protozoan purine auxotroph possessing a unique purine salvage pathway consisting of a bacterial type purine nucleoside phosphorylase (PNP) and a purine nucleoside kinase. Thus, T. vaginalis PNP (TvPNP) functions in the reverse direction relative to the PNPs in other organisms. Immucillin-A (ImmA) and DADMe-Immucillin-A (DADMe-ImmA) are transition state mimics of adenosine with geometric and electrostatic features that resemble early and late transition states of adenosine at the transition state stabilized by TvPNP. ImmA demonstrates slow-onset tight-binding inhibition with TvPNP, to give an equilibrium dissociation constant of 87 pM, an inhibitor release half-time of 17.2 min, and a Km/Kd ratio of 70,100. DADMe-ImmA resembles a late ribooxacarbenium ion transition state for TvPNP to give a dissociation constant of 30 pM, an inhibitor release half-time of 64 min, and a Km/Kd ratio of 203,300. The tight binding of DADMe-ImmA supports a late SN1 transition state. Despite their tight binding to TvPNP, ImmA and DADMe-ImmA are weak inhibitors of human and P. falciparum PNPs. The crystal structures of the TvPNP x ImmA x PO4 and TvPNP x DADMe-ImmA x PO4 ternary complexes differ from previous structures with substrate analogues. The tight binding with DADMe-ImmA is in part due to a 2.7 A ionic interaction between a PO4 oxygen and the N1' cation of the hydroxypyrrolidine and is weaker in the TvPNP x ImmA x PO4 structure at 3.5 A. However, the TvPNP x ImmA x PO4 structure includes hydrogen bonds between the 2'-hydroxyl and the protein that are not present in TvPNP x DADMe-ImmA x PO4. These structures explain why DADMe-ImmA binds tighter than ImmA. Immucillin-H is a 12 nM inhibitor of TvPNP but a 56 pM inhibitor of human PNP. And this difference is explained by isotope-edited difference infrared spectroscopy with [6-18O]ImmH to establish that O6 is the keto tautomer in TvPNP x ImmH x PO4, causing an unfavorable leaving-group interaction.
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Affiliation(s)
- Agnes Rinaldo-Matthis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Corin Wing
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Mahmoud Ghanem
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Hua Deng
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Peng Wu
- Department of Pharmaceutical Chemistry, University of California San Francisco, Mission Bay, Genetech Hall, Suite N572, San Francisco, CA94143-2880
| | - Arti Gupta
- Department of Pharmaceutical Chemistry, University of California San Francisco, Mission Bay, Genetech Hall, Suite N572, San Francisco, CA94143-2880
| | - Peter C. Tyler
- The Carbohydrate Chemistry Team, Industrial Research Ltd, New Zealand
| | - Gary B. Evans
- The Carbohydrate Chemistry Team, Industrial Research Ltd, New Zealand
| | | | - Steven C. Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Ching C. Wang
- Department of Pharmaceutical Chemistry, University of California San Francisco, Mission Bay, Genetech Hall, Suite N572, San Francisco, CA94143-2880
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, 10461
- *Corresponding author footnote: e-mail, : Telephone, (718) 430-2813; Fax: 718-430-8565
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Ali V, Nozaki T. Current therapeutics, their problems, and sulfur-containing-amino-acid metabolism as a novel target against infections by "amitochondriate" protozoan parasites. Clin Microbiol Rev 2007; 20:164-87. [PMID: 17223627 PMCID: PMC1797636 DOI: 10.1128/cmr.00019-06] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The "amitochondriate" protozoan parasites of humans Entamoeba histolytica, Giardia intestinalis, and Trichomonas vaginalis share many biochemical features, e.g., energy and amino acid metabolism, a spectrum of drugs for their treatment, and the occurrence of drug resistance. These parasites possess metabolic pathways that are divergent from those of their mammalian hosts and are often considered to be good targets for drug development. Sulfur-containing-amino-acid metabolism represents one such divergent metabolic pathway, namely, the cysteine biosynthetic pathway and methionine gamma-lyase-mediated catabolism of sulfur-containing amino acids, which are present in T. vaginalis and E. histolytica but absent in G. intestinalis. These pathways are potentially exploitable for development of drugs against amoebiasis and trichomoniasis. For instance, L-trifluoromethionine, which is catalyzed by methionine gamma-lyase and produces a toxic product, is effective against T. vaginalis and E. histolytica parasites in vitro and in vivo and may represent a good lead compound. In this review, we summarize the biology of these microaerophilic parasites, their clinical manifestation and epidemiology of disease, chemotherapeutics, the modes of action of representative drugs, and problems related to these drugs, including drug resistance. We further discuss our approach to exploit unique sulfur-containing-amino-acid metabolism, focusing on development of drugs against E. histolytica.
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Affiliation(s)
- Vahab Ali
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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25
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Xiao JC, Xie LF, Fang SL, Gao MY, Zhu Y, Song LY, Zhong HM, Lun ZR. Symbiosis of Mycoplasma hominis in Trichomonas vaginalis may link metronidazole resistance in vitro. Parasitol Res 2006; 100:123-30. [PMID: 16847608 DOI: 10.1007/s00436-006-0215-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 04/16/2006] [Indexed: 11/25/2022]
Abstract
Fourteen of 28 Trichomonas vaginalis isolates collected from patients in Guangzhou, China from 2003 to 2004 were found to be naturally infected with Mycoplasma hominis, as determined by PCR using specific primers. In vitro metronidazole sensitivity assay of the 28 isolates revealed four displaying low susceptibility [minimum lethal concentration (MLC)= approximately 13-25 microg/ml] and another four displaying high resistance (MLC=50-100 microg/ml). The overwhelming majority of these resistant isolates (7/8) were mycoplasma-infected. The mean of MLCs of mycoplasma-infected isolates is approximately 10-fold higher than the mean of noninfected isolates (p=0.029). Sequence analyses of PCR-amplified small subunit-large subunit rRNA interspacer regions (ITS1/5.8S/ITS2) revealed that 23 of the 28 samples are identical, the remaining five being separable into two groups, each with a single point mutation. These internal transcribed spacer sequence variants are associated neither with mycoplasma infection nor with drug resistance. In contrast, random amplified polymorphic DNA analyses of DNAs using 10 different primers showed that the drug-resistant isolates are clustered together in association with mycoplasma infection, albeit more loosely. Taken together, the results obtained from this study suggest that in vitro metronidazole resistance of T. vaginalis is related to mycoplasma infection of this protozoan.
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Affiliation(s)
- J C Xiao
- Center for Parasitic Organisms, State Key Laboratory of Biocontrol and Key Laboratory for Tropical Diseases Control of the Ministry of Education, School of Life Sciences, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275, People's Republic of China
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26
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Upcroft JA, Delgadillo-Correa MG, Dunne RL, Sturm AW, Johnson PJ, Upcroft P. Genotyping Trichomonas vaginalis. Int J Parasitol 2006; 36:821-8. [PMID: 16698025 DOI: 10.1016/j.ijpara.2006.02.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 02/15/2006] [Accepted: 02/22/2006] [Indexed: 11/23/2022]
Abstract
A genotyping method has been developed to distinguish each Trichomonas vaginalis isolate and has provided the first genome mapping studies of this protist with an estimated 180Mb genome. The technique was developed using high molecular weight DNA prepared from five laboratory isolates from Australia and USA and 20 clinical isolates from South Africa. Inhibition of the notorious T. vaginalis endogenous nucleases by addition of potent inhibitors was essential to the success of this study. Chromosomal DNA larger than 2.2Mb was macrorestricted to a minimum segment size of approximately 50kb, separated by pulsed field gel electrophoresis and hybridised with a variety of gene probes. Each isolate generated a unique pattern that was distinguished by each of the probes. Four single copy gene probes (fd, hmp35, ibp39 and pfoD) were identified but probes which identified several bands (pfoB and alpha-scs) per isolate were most informative for genotyping. The pyruvate:ferredoxin oxidoreductase B gene probe identified two to seven copies of pfoB (or its closely related homologue pfoA) per genome in different isolates and is an obvious candidate probe to identify epidemiological linkage between infections by this genotyping method. Cleavage of the genomes into smaller fragments failed to distinguish isolates from diverse locations indicating the proximal regions of genes are conserved.
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Affiliation(s)
- Jacqueline A Upcroft
- Queensland Institute of Medical Research, and Australian Centre for International and Tropical Health and Nutrition, The University of Queensland, Brisbane, Queensland 4029, Australia.
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27
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Mead JR, Fernadez M, Romagnoli PA, Secor WE. Use of Trichomonas vaginalis clinical isolates to evaluate correlation of gene expression and metronidazole resistance. J Parasitol 2006; 92:196-9. [PMID: 16629339 DOI: 10.1645/ge-616r.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We investigated whether variations in gene expression of enzymes associated with anaerobic resistance of laboratory-derived strains of Trichomonas vaginalis could be detected in a group of 28 clinical isolates with variations in metronidazole sensitivity. We compared isolates by real-time PCR because this method allows for highly sensitive quantification of mRNA and for evaluation of several genes simultaneously. We found that PFOR gene A mRNA levels were highly correlated with PFOR gene B levels, as well as the D subunit of malic enzyme and ferrodoxin. Ferrodoxin mRNA expression was also significantly correlated with that of malic enzyme and hydrogenase. However, when we evaluated relationships between these enzymes and resistance to metronidazole, we found no significant correlations between aerobic or anaerobic in vitro sensitivity to drug and mRNA levels of any of the enzymes tested. Similarly, using a Student's t-test, no significant differences in enzyme mRNA levels were observed between isolates separated by metronidazole resistance or susceptibility. The lack of correlation between gene expression and resistance or susceptibility could be the result of differences in expression at the protein level or because other biochemical pathways or genes are involved in the resistance observed in clinical settings.
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Affiliation(s)
- J R Mead
- Veterans Affairs Medical Center, Decatur, Georgia 30033, USA.
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28
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Upcroft JA, Dunn LA, Wright JM, Benakli K, Upcroft P, Vanelle P. 5-Nitroimidazole drugs effective against metronidazole-resistant Trichomonas vaginalis and Giardia duodenalis. Antimicrob Agents Chemother 2006; 50:344-7. [PMID: 16377707 PMCID: PMC1346785 DOI: 10.1128/aac.50.1.344-347.2006] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Metronidazole (Mz)-resistant Giardia and Trichomonas were inhibited by 1 of 30 new 5-nitroimidazole drugs. Another five drugs were effective against some but not all of the Mz-resistant parasites. This study provides the incentive for the continued design of 5-nitroimidazole drugs to bypass cross-resistance among established 5-nitromidazole antiparasitic drugs.
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Affiliation(s)
- Jacqueline A Upcroft
- The Queensland Institute of Medical Research and ACITHN, P.O. Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia.
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29
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Mundodi V, Kucknoor AS, Klumpp DJ, Chang TH, Alderete JF. Silencing the ap65 gene reduces adherence to vaginal epithelial cells by Trichomonas vaginalis. Mol Microbiol 2004; 53:1099-108. [PMID: 15306014 PMCID: PMC2562645 DOI: 10.1111/j.1365-2958.2004.04192.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Host parasitism by Trichomonas vaginalis is complex and in part mediated by adherence to vaginal epithelial cells (VECs). Four trichomonad surface proteins bind VECs as adhesins, and AP65 is a major adhesin with sequence identity to an enzyme of the hydrogenosome organelle that is involved in energy generation. In order to perform genetic analysis and assess the role of AP65 in T. vaginalis adherence, we silenced expression of ap65 using antisense RNA. The gene for ap65 was inserted into the vector pBS-neo in sense and antisense orientations to generate plasmids pBS-neoS (S) and pBS-neoAS (AS), respectively. Trichomonads were then transfected with S and AS plasmids for selection of stable transfectants using Geneticin, and the presence of plasmid in transfectants was confirmed by polymerase chain reaction of the neo gene. Reverse transcription polymerase chain reaction and Northern blot analysis showed decreased amounts of ap65 transcript in AS transfected parasites. Growth kinetics of the antisense-transfected and wild type organisms were similar, suggesting that silencing AP65 did not affect overall energy generation for growth. Immunoblot analysis using monoclonal antibody (mAb) to AP65 of AS transfectants showed decreased amounts of AP65 when compared to wild type or S transfectants. Not unexpectedly, this corresponded to decreased amounts of AP65 bound to VECs in a functional ligand assay. Reduction in parasite surface expression of AP65 was related to lower levels of adherence to VECs by AS-transfectants compared to control organisms. Antisense silencing of ap65 was not alleviated by growth of trichomonads in high iron, which up-regulates transcription of ap65. Our work reaffirms the role for AP65 as an adhesin, and in addition, we demonstrate antisense RNA gene silencing in T. vaginalis to study the contribution of specific genes in pathogenesis.
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Affiliation(s)
- V Mundodi
- Department of Microbiology, University of Texas Health Science Center, San Antonio, TX, USA
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30
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Abstract
The flagellated protozoa Giardia duodenalis is the most commonly detected parasite in the intestinal tract of humans. Infections with the parasite result in diarrhoeal disease in humans and animals, with infants at risk from failure-to-thrive syndrome. The incidence of giardiasis worldwide may be as high as 1000 million cases. Current recommended treatments include the nitroheterocyclic drugs tinidazole, metronidazole and furazolidone, the substituted acridine, quinacrine, and the benzimidazole, albendazole. Paromomycin is also used in some situations, and nitazoxanide is proving to be useful. However, treatment failures have been reported with all of the common antigiardial agents, and drug resistance to all available drugs has been demonstrated in the laboratory. In addition, clinical resistance has been reported, including cases where patients failed both metronidazole and albendazole treatments. The identification of new antigiardial drugs is an important consideration for the future, but maintaining the usefulness of the existing drugs is the most cost-effective measure to ensure the continued availability of antigiardial drugs.
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Affiliation(s)
- Janelle M Wright
- Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Queensland 4029, Australia.
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31
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Land KM, Delgadillo-Correa MG, Tachezy J, Vanacova S, Hsieh CL, Sutak R, Johnson PJ. Targeted gene replacement of a ferredoxin gene in Trichomonas vaginalis does not lead to metronidazole resistance. Mol Microbiol 2004; 51:115-22. [PMID: 14651615 DOI: 10.1046/j.1365-2958.2003.03791.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ferredoxin, Fd, is often deficient in metronidazole-resistant strains of Trichomonas vaginalis and is thought to be necessary for drug activation. To directly test whether Fd is essential for metronidazole susceptibility, gene replacement technology has been developed for T. vaginalis. The selectable marker gene neomycin phosphotransferase (NEO) flanked by approximately 2.6 and approximately 2.0 kBp of the Fd 5' and 3' flanking regions (pKO-FD-NEO) was introduced into cells on linear DNA and selected for NEO gene expression. Stable transformants were shown to contain the NEO gene in the Fd locus and to have completely lost the Fd gene. Northern and immunoblot analyses confirm the loss of Fd mRNA and protein in pKO-FD-NEO cells. Analyses of the activity of hydrogenosomal proteins in Fd KO cells show a fourfold increase in hydrogenase activity and a 95% decrease in pyruvate/ferredoxin oxidoreductase (PFO) activity. In contrast, PFO and hydrogenase mRNA levels are unchanged. Surprisingly, Fd KO cells are not resistant to metronidazole under aerobic or anaerobic conditions. These cells are capable of producing molecular hydrogen, albeit at 50% the level of the parental strain, demonstrating that the Fd gene product eliminated in KO cells is neither necessary for hydrogen production nor metronidazole activation. Together these data indicate the presence of unidentified Fds or flavodoxins capable of drug activation or an unidentified mechanism that does not require either PFO or Fd for metronidazole activation.
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Affiliation(s)
- Kirkwood M Land
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles School of Medicine, Los Angeles, California 90095-1489, USA
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32
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Dunne RL, Dunn LA, Upcroft P, O'Donoghue PJ, Upcroft JA. Drug resistance in the sexually transmitted protozoan Trichomonas vaginalis. Cell Res 2003; 13:239-49. [PMID: 12974614 DOI: 10.1038/sj.cr.7290169] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Trichomoniasis is the most common, sexually transmitted infection. It is caused by the flagellated protozoan parasite Trichomonas vaginalis. Symptoms include vaginitis and infections have been associated with preterm delivery, low birth weight and increased infant mortality, as well as predisposing to HIV/AIDS and cervical cancer. Trichomoniasis has the highest prevalence and incidence of any sexually transmitted infection. The 5-nitroimidazole drugs, of which metronidazole is the most prescribed, are the only approved, effective drugs to treat trichomoniasis. Resistance against metronidazole is frequently reported and cross-resistance among the family of 5-nitroimidazole drugs is common, leaving no alternative for treatment, with some cases remaining unresolved. The mechanism of metronidazole resistance in T. vaginalis from treatment failures is not well understood, unlike resistance which is developed in the laboratory under increasing metronidazole pressure. In the latter situation, hydrogenosomal function which is involved in activation of the prodrug, metronidazole, is down-regulated. Reversion to sensitivity is incomplete after removal of drug pressure in the highly resistant parasites while clinically resistant strains, so far analysed, maintain their resistance levels in the absence of drug pressure. Although anaerobic resistance has been regarded as a laboratory induced phenomenon, it clearly has been demonstrated in clinical isolates. Pursuit of both approaches will allow dissection of the underlying mechanisms. Many alternative drugs and treatments have been tested in vivo in cases of refractory trichomoniasis, as well as in vitro with some successes including the broad spectrum anti-parasitic drug nitazoxanide. Drug resistance incidence in T. vaginalis appears to be on the increase and improved surveillance of treatment failures is urged.
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Affiliation(s)
- Rebecca L Dunne
- The Queensland Institute of Medical Research, The Australian Centre for International and Tropical Health and Nutrition, Brisbane, Queensland 4029, Australia
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33
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Rasoloson D, Vanacova S, Tomkova E, Razga J, Hrdy I, Tachezy J, Kulda J. Mechanisms of in vitro development of resistance to metronidazole in Trichomonas vaginalis. MICROBIOLOGY (READING, ENGLAND) 2002; 148:2467-2477. [PMID: 12177340 DOI: 10.1099/00221287-148-8-2467] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Development of resistance against metronidazole and mechanisms responsible for this process were studied in a sexually transmitted pathogen of humans, Trichomonas vaginalis. Monitoring of changes in metabolism and protein expression that accompanied increasing resistance of strains derived from a common drug-susceptible parent (TV 10-02) showed the multistep character of the process. The aerobic type of resistance known to occur in isolates from patients non-responsive to treatment appeared at the earliest stage, followed by development of the anaerobic type of resistance which was accompanied by gradual loss of hydrogenosomal proteins associated with drug-activating pathways [pyruvate:ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin]. Unexpectedly, the loss of PFOR did not result in acquisition of full anaerobic resistance, thus indicating an alternative source of electrons required for the drug activation. These data suggest involvement of the oxidative decarboxylation of malate in hydrogenosomes, catalysed by NAD(+)-dependent malic enzyme and subsequent transfer of reduced equivalents to the drug via NADH:ferredoxin oxidoreductase and ferredoxin. Accordingly, all components of this pathway were eliminated before the resistance was fully developed. Resistant Trichomonas vaginalis compensated the impaired function of hydrogenosomes by enhanced conversion of pyruvate to lactate in the cytosol. Further analysis of the two key enzymes involved in metronidazole activation by Northern blotting and assay for nascent mRNA showed that the insufficient expression of the PFOR protein results from decreased gene transcription, while down-regulation of malic enzyme is controlled at the mRNA level.
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Affiliation(s)
- Dominique Rasoloson
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Stepanka Vanacova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Eva Tomkova
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Jakub Razga
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Ivan Hrdy
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Jan Tachezy
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
| | - Jaroslav Kulda
- Department of Parasitology, Faculty of Science, Charles University in Prague, Vinic̆ná 7, 128 44 Prague 2, Czech Republic1
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34
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Sangster N, Batterham P, Chapman HD, Duraisingh M, Le Jambre L, Shirley M, Upcroft J, Upcroft P. Resistance to antiparasitic drugs: the role of molecular diagnosis. Int J Parasitol 2002; 32:637-53. [PMID: 11943235 DOI: 10.1016/s0020-7519(01)00365-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Chemotherapy is central to the control of many parasite infections of both medical and veterinary importance. However, control has been compromised by the emergence of drug resistance in several important parasite species. Such parasites cover a broad phylogenetic range and include protozoa, helminths and arthropods. In order to achieve effective parasite control in the future, the recognition and diagnosis of resistance will be crucial. This demand for early, accurate diagnosis of resistance to specific drugs in different parasite species can potentially be met by modern molecular techniques. This paper summarises the resistance status of a range of important parasites and reviews the available molecular techniques for resistance diagnosis. Opportunities for applying successes in some species to other species where resistance is less well understood are explored. The practical application of molecular techniques and the impact of the technology on improving parasite control are discussed.
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Affiliation(s)
- Nicholas Sangster
- Faculty of Veterinary Science, University of Sydney, 2006, Sydney, Australia.
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35
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Land KM, Delgadillo MG, Johnson PJ. In vivo expression of ferredoxin in a drug resistant trichomonad increases metronidazole susceptibility. Mol Biochem Parasitol 2002; 121:153-7. [PMID: 11985873 DOI: 10.1016/s0166-6851(02)00025-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Kirkwood M Land
- Department of Microbiology, Immunology and Molecular Genetics, The Molecular Biology Institute, University of California at Los Angeles, 90095-1489, USA
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36
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Abstract
A simple technique for routine, reproducible global surveillance of the drug susceptibility status of the anaerobic protozoa Trichomonas, Entamoeba, and Giardia is described. Data collected using this technique can be readily compared among different laboratories and with previously reported data. The technique employs a commercially available sachet and bag system to generate a low-oxygen environment and log(2) drug dilutions in microtiter plates, which can be monitored without aerobic exposure, to assay drug-resistant laboratory lines and clinically resistant isolates. MICs (after 2 days) of 3.2 and 25 microM indicated metronidazole-sensitive and highly clinically resistant isolates of T. vaginalis in anaerobic assays, respectively. The aerobic MICs were 25 and >200 microM. MICs (1 day) of 12.5 to 25 microM were found for axenic lines of E. histolytica, and MICs for G. duodenalis (3 days) ranged from 6.3 microM for metronidazole-sensitive isolates to 50 microM for laboratory metronidazole-resistant lines. This technique should encourage more extensive monitoring of drug resistance in these organisms.
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Affiliation(s)
- J A Upcroft
- Queensland Institute of Medical Research, Brisbane, Queensland 4029, Australia.
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37
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Vázquez F, José García M, Pérez F, Palacio V. [Trichomonas vaginalis: treatment and resistance to nitroimidazoles]. Enferm Infecc Microbiol Clin 2001; 19:114-24. [PMID: 11333589 DOI: 10.1016/s0213-005x(01)72580-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- F Vázquez
- Departamento de Biología Funcional. Area de Microbiología. Facultad de Medicina de Oviedo y Servicio de Microbiología. Hospital Monte Naranco.
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38
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Land KM, Clemens DL, Johnson PJ. Loss of multiple hydrogenosomal proteins associated with organelle metabolism and high-level drug resistance in trichomonads. Exp Parasitol 2001; 97:102-10. [PMID: 11281707 DOI: 10.1006/expr.2001.4587] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Land, K. M., Clemens, D. L., and Johnson, P. J. 2001. Loss of multiple hydrogenosomal proteins associated with organelle metabolism and high-level drug resistance in trichomonads. Experimental Parasitology 97, 102-110. In trichomonads, metronidazole is activated to its cytotoxic form in a specialized energy-producing organelle called the hydrogenosome. Electron transport components in the organelle, pyruvate:ferredoxin oxidoreductase and ferredoxin, donate a single electron to the drug, converting it to a cytotoxic free radical. Previous biochemical analyses of enzyme activities of highly resistant strains of both Trichomonas vaginalis and Tritrichomonas foetus reveal undetectable activity for pyruvate:ferredoxin oxidoreductase and another hydrogenosomal enzyme, hydrogenase. We have chosen to analyze a highly drug-resistant strain of T. foetus and its parental drug-sensitive strain from which it was derived to study the molecular basis for these enzyme defects. Quantitation of pyruvate:ferredoxin oxidoreductase and ferredoxin levels in sensitive and resistant cells shows a marked reduction of these proteins in the resistant strain. RNA analysis reveals an approximately 60% reduction in pyruvate:ferredoxin oxidoreductase mRNA and 90-98% reduction in mRNA levels encoding hydrogenosomal proteins hydrogenase, ferredoxin, and malic enzyme. We have measured the levels of transcription of these genes and observed 60% reduction of pyruvate:ferredoxin oxidoreductase gene transcription and 85% reduction in malic enzyme gene transcription in the resistant strain. The reduction or absence of these organellar proteins is likely to reduce or eliminate the ability of the cell to activate the drug, giving rise to the highly resistant phenotype. Ultrastructural analysis of thin sections revealed that resistant cells are 20% smaller in size and hydrogenosomes in resistant cells are approximately one-third the size of those in the drug-sensitive parental strain. These data suggest that altered gene expression of multiple hydrogenosomal proteins results in the modification of the organelle and leads to drug resistance.
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Affiliation(s)
- K M Land
- Department of Microbiology and Immunology, Division of Infectious Diseases, University of California at Los Angeles, 1602 Molecular Sciences Building, 405 Hilgard Avenue, Los Angeles, CA 90095-1489, USA
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39
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Abstract
The anaerobic protozoa Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica infect up to a billion people each year. G. duodenalis and E. histolytica are primarily pathogens of the intestinal tract, although E. histolytica can form abscesses and invade other organs, where it can be fatal if left untreated. T. vaginalis infection is a sexually transmitted infection causing vaginitis and acute inflammatory disease of the genital mucosa. T. vaginalis has also been reported in the urinary tract, fallopian tubes, and pelvis and can cause pneumonia, bronchitis, and oral lesions. Respiratory infections can be acquired perinatally. T. vaginalis infections have been associated with preterm delivery, low birth weight, and increased mortality as well as predisposing to human immunodeficiency virus infection, AIDS, and cervical cancer. All three organisms lack mitochondria and are susceptible to the nitroimidazole metronidazole because of similar low-redox-potential anaerobic metabolic pathways. Resistance to metronidazole and other drugs has been observed clinically and in the laboratory. Laboratory studies have identified the enzyme that activates metronidazole, pyruvate:ferredoxin oxidoreductase, to its nitroso form and distinct mechanisms of decreasing drug susceptibility that are induced in each organism. Although the nitroimidazoles have been the drug family of choice for treating the anaerobic protozoa, G. duodenalis is less susceptible to other antiparasitic drugs, such as furazolidone, albendazole, and quinacrine. Resistance has been demonstrated for each agent, and the mechanism of resistance has been investigated. Metronidazole resistance in T. vaginalis is well documented, and the principal mechanisms have been defined. Bypass metabolism, such as alternative oxidoreductases, have been discovered in both organisms. Aerobic versus anaerobic resistance in T. vaginalis is discussed. Mechanisms of metronidazole resistance in E. histolytica have recently been investigated using laboratory-induced resistant isolates. Instead of downregulation of the pyruvate:ferredoxin oxidoreductase and ferredoxin pathway as seen in G. duodenalis and T. vaginalis, E. histolytica induces oxidative stress mechanisms, including superoxide dismutase and peroxiredoxin. The review examines the value of investigating both clinical and laboratory-induced syngeneic drug-resistant isolates and dissection of the complementary data obtained. Comparison of resistance mechanisms in anaerobic bacteria and the parasitic protozoa is discussed as well as the value of studies of the epidemiology of resistance.
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Affiliation(s)
- P Upcroft
- Queensland Institute of Medical Research and The Tropical Health Program, Australian Centre for International and Tropical Health and Nutrition, The University of Queensland, The Bancroft Centre, Brisbane, Queensland 4029, Australia.
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40
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Liu SM, Brown DM, O'Donoghue P, Upcroft P, Upcroft JA. Ferredoxin involvement in metronidazole resistance of Giardia duodenalis. Mol Biochem Parasitol 2000; 108:137-40. [PMID: 10802327 DOI: 10.1016/s0166-6851(00)00194-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S M Liu
- The Queensland Institute of Medical Research, 300 Herston Rd, Herston, Brisbane, Qld, Australia
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41
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Dan M, Wang AL, Wang CC. Inhibition of pyruvate-ferredoxin oxidoreductase gene expression in Giardia lamblia by a virus-mediated hammerhead ribozyme. Mol Microbiol 2000; 36:447-56. [PMID: 10792730 DOI: 10.1046/j.1365-2958.2000.01863.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Giardia lamblia is a primitive eukaryotic microorganism that derives its metabolic energy primarily from anaerobic glycolysis. In trophozoites, pyruvate-ferredoxin oxidoreductase (PFOR) converts pyruvate to acetyl-CoA with the transfer of a pair of electrons to ferredoxin, which can then reduce metronidazole and activate it into a potent antigiardiasis agent. It is unclear, however, whether this anaerobic disposal of electrons is essential for the energy metabolism in Giardia. In the present study, cDNAs encoding hammerhead ribozyme flanked with various lengths of antisense PFOR RNA were cloned into a viral vector pC631pac derived from the genome of giardiavirus (GLV). RNA transcripts of the plasmids showed high cleavage activities on PFOR mRNA in vitro. They were introduced into GLV-infected G. lamblia trophozoites by electroporation and stablized in the transfected cells via serial passages under puromycin selection. PFOR mRNA and enzyme activity in the transfected cells were decreased by 46-60% with the ribozyme PRzS flanked with 20 nt PFOR antisense RNA on each arm and by 69-80% with the ribozyme PRzL flanked with 600 and 1500 nt PFOR antisense RNA. PRzS without the inserted ribozyme or ribozyme flanked with alcohol dehydrogenase E antisense RNA showed no effect on PFOR mRNA and activity. The ribozyme-transfected cells demonstrated significantly enhanced resistance to metronidazole and grew equally well under anaerobic and aerobic conditions. In contrast, the wild-type cells grew slightly better anaerobically than the transfectants but did not grow at all in aerobic conditions. Thus, the reduced PFOR expression enables Giardia to grow under molecular oxygen and the presence of PFOR enhances the anaerobic growth of Giardia with an increased susceptibility towards metronidazole. In addition, this study demonstrated for the first time the feasibility of using a viral RNA vector to express a ribozyme targeted at a specific mRNA in G. lamblia to reduce the expression of a specific gene.
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Affiliation(s)
- M Dan
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143-0446, USA
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42
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Gero AM, Kang EW, Harvey JE, Schofield PJ, Clinch K, Furneaux RH. Trichomonas vaginalis: detection of nucleoside hydrolase activity as a potential screening procedure. Exp Parasitol 2000; 94:125-8. [PMID: 10673349 DOI: 10.1006/expr.1999.4484] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- A M Gero
- School of Biochemistry and Molecular Genetics, The University of New South Wales, Sydney, NSW, 2052, Australia.
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43
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Abstract
Trichomonas vaginalis is emerging as a major pathogen of men and women and is associated with serious health consequences. Advances in diagnosis and treatment are presented. The complexity of trichomonad pathogenesis is illustrated in the interaction of this parasite with human cells, tissues and the immune system. It is now becoming evident that the interaction of trichomonads with the host is frequently modulated by environmental signals. The molecular biology of trichomonads is still in its infancy, but analysis of genes, genomic structure and transcriptional mechanisms suggest that trichomonads combine both prokaryotic and eukaryotic features. Evidence for the ancient divergence of trichomonads from other eukaryotic lineages is discussed.
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Affiliation(s)
- Michael W. Lehker
- aDepartment of Biological Sciences, The University of Texas at El Paso, El Paso, and bDepartment of Microbiology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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44
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Land KM, Johnson PJ. Molecular basis of metronidazole resistance in pathogenic bacteria and protozoa. Drug Resist Updat 1999; 2:289-294. [PMID: 11504503 DOI: 10.1054/drup.1999.0104] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The molecular basis of metronidazole resistance has been examined in anaerobic bacteria, such as Bacteroides, Clostridium, and Helicobacter, and anaerobic parasitic protists such as Giardia, Entamoeba, and trichomonads. A variety of enzymatic and cellular alterations have been shown to correlate with metronidazole susceptibility in these pathogens; however, a common theme has been revealed. Resistant cells are typically deficient in drug activation. The frequent correlation between metronidazole resistance and ineffective drug activation suggests that drug resistance is the result of modification of proteins involved in drug activation. Copyright 1999 Harcourt Publishers Ltd.
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Affiliation(s)
- Kirkwood M. Land
- Department of Microbiology, UCLA School of Medicine, Los Angeles, CA, 90095-1489, USA
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45
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Abstract
In anaerobes, decarboxylation of pyruvate is executed by the enzyme pyruvate:ferredoxin oxidoreductase, which donates electrons to ferredoxin. The pyruvate:ferredoxin oxidoreductase and its homologues utilise many alternative substrates in bacterial anaerobes. The pyruvate:ferredoxin oxidoreductase from anaerobic protozoa, such as Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica have retained this diversity in usage of alternative keto acids for energy production utilising a wide variety of substrates. In addition to this flexibility, both T. vaginalis and G. duodenalis have alternative enzymes that are active in metronidazole-resistant parasites and that do not necessarily involve donation of electrons to characterized ferredoxins. Giardia duodenalis has two oxoacid oxidoreductases, including pyruvate:ferredoxin oxidoreductase and T. vaginalis has at least three. These alternative oxoacid oxidoreductases apparently do not share homology with the characterized pyruvate:ferredoxin oxidoreductase in either organism. Independently, both G. duodenalis and T. vaginalis have retained alternative oxoacid oxidoreductase activities that are clearly important for the survival of these parasitic protists.
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Affiliation(s)
- J A Upcroft
- Queensland Institute of Medical Research, Brisbane.
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46
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Upcroft JA, Campbell RW, Benakli K, Upcroft P, Vanelle P. Efficacy of new 5-nitroimidazoles against metronidazole-susceptible and -resistant Giardia, Trichomonas, and Entamoeba spp. Antimicrob Agents Chemother 1999; 43:73-6. [PMID: 9869568 PMCID: PMC89023 DOI: 10.1128/aac.43.1.73] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/1998] [Accepted: 10/12/1998] [Indexed: 11/20/2022] Open
Abstract
The efficacies of 12 5-nitroimidazole compounds and 1 previously described lactam-substituted nitroimidazole with antiparasitic activity, synthesized via SRN1 and subsequent reactions, were assayed against the protozoan parasites Giardia duodenalis, Trichomonas vaginalis, and Entamoeba histolytica. Two metronidazole-sensitive lines and two metronidazole-resistant lines of Giardia and one line each of metronidazole-sensitive and -resistant Trichomonas were tested. All except one of the compounds were as effective or more effective than metronidazole against Giardia and Trichomonas, but none was as effective overall as the previously described 2-lactam-substituted 5-nitroimidazole. None of the compounds was markedly more effective than metronidazole against Entamoeba. Significant cross-resistance between most of the drugs tested and metronidazole was evident among metronidazole-resistant lines of Giardia and Trichomonas. However, some drugs were lethal to metronidazole-resistant Giardia and had minimum lethal concentrations similar to that of metronidazole for drug-susceptible parasites. This study emphasizes the potential in developing new nitroimidazole drugs which are more effective than metronidazole and which may prove to be useful clinical alternatives to metronidazole.
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Affiliation(s)
- J A Upcroft
- The Queensland Institute of Medical Research, Brisbane, Queensland 4029, Australia.
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47
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McFadden GI. Meeting Report: XIIth Meeting of the International Society for Evolutionary Protistology Flagstaff, USA, August 2-4, 1998. Protist 1998. [PMID: 23194711 DOI: 10.1016/s1434-4610(98)70035-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- G I McFadden
- Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville VIC 3052, Australia
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