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Bertuccini L, Boussadia Z, Salzano AM, Vanni I, Passerò I, Nocita E, Scaloni A, Sanchez M, Sargiacomo M, Fiani ML, Tosini F. Unveiling Cryptosporidium parvum sporozoite-derived extracellular vesicles: profiling, origin, and protein composition. Front Cell Infect Microbiol 2024; 14:1367359. [PMID: 38660488 PMCID: PMC11039866 DOI: 10.3389/fcimb.2024.1367359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Cryptosporidium parvum is a common cause of a zoonotic disease and a main cause of diarrhea in newborns. Effective drugs or vaccines are still lacking. Oocyst is the infective form of the parasite; after its ingestion, the oocyst excysts and releases four sporozoites into the host intestine that rapidly attack the enterocytes. The membrane protein CpRom1 is a large rhomboid protease that is expressed by sporozoites and recognized as antigen by the host immune system. In this study, we observed the release of CpRom1 with extracellular vesicles (EVs) that was not previously described. To investigate this phenomenon, we isolated and resolved EVs from the excystation medium by differential ultracentrifugation. Fluorescence flow cytometry and transmission electron microscopy (TEM) experiments identified two types of sporozoite-derived vesicles: large extracellular vesicles (LEVs) and small extracellular vesicles (SEVs). Nanoparticle tracking analysis (NTA) revealed mode diameter of 181 nm for LEVs and 105 nm for SEVs, respectively. Immunodetection experiments proved the presence of CpRom1 and the Golgi protein CpGRASP in LEVs, while immune-electron microscopy trials demonstrated the localization of CpRom1 on the LEVs surface. TEM and scanning electron microscopy (SEM) showed that LEVs were generated by means of the budding of the outer membrane of sporozoites; conversely, the origin of SEVs remained uncertain. Distinct protein compositions were observed between LEVs and SEVs as evidenced by their corresponding electrophoretic profiles. Indeed, a dedicated proteomic analysis identified 5 and 16 proteins unique for LEVs and SEVs, respectively. Overall, 60 proteins were identified in the proteome of both types of vesicles and most of these proteins (48 in number) were already identified in the molecular cargo of extracellular vesicles from other organisms. Noteworthy, we identified 12 proteins unique to Cryptosporidium spp. and this last group included the immunodominant parasite antigen glycoprotein GP60, which is one of the most abundant proteins in both LEVs and SEVs.
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Affiliation(s)
| | - Zaira Boussadia
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
| | - Anna Maria Salzano
- Proteomics, Metabolomics and Mass Spectrometry laboratory, ISPAAM, Consiglio Nazionale delle Ricerche, Portici, Italy
| | - Ilaria Vanni
- Department of Food Safety, Nutrition and Veterinary Public Health, SANV, Istituto Superiore di Sanità, Rome, Italy
| | - Ilaria Passerò
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Emanuela Nocita
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Andrea Scaloni
- Proteomics, Metabolomics and Mass Spectrometry laboratory, ISPAAM, Consiglio Nazionale delle Ricerche, Portici, Italy
| | | | - Massimo Sargiacomo
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Maria Luisa Fiani
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Fabio Tosini
- Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
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Verma K, Lahariya AK, Verma G, Kumari M, Gupta D, Maurya N, Verma AK, Mani A, Schneider KA, Bharti PK. Screening of potential antiplasmodial agents targeting cysteine protease-Falcipain 2: a computational pipeline. J Biomol Struct Dyn 2023; 41:8121-8164. [PMID: 36218071 DOI: 10.1080/07391102.2022.2130984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/24/2022] [Indexed: 10/17/2022]
Abstract
The spread of antimalarial drug resistance is a substantial challenge in achieving global malaria elimination. Consequently, the identification of novel therapeutic candidates is a global health priority. Malaria parasite necessitates hemoglobin degradation for its survival, which is mediated by Falcipain 2 (FP2), a promising antimalarial target. In particular, FP2 is a key enzyme in the erythrocytic stage of the parasite's life cycle. Here, we report the screening of approved drugs listed in DrugBank using a computational pipeline that includes drug-likeness, toxicity assessments, oral toxicity evaluation, oral bioavailability, docking analysis, maximum common substructure (MCS) and molecular dynamics (MD) Simulations analysis to identify capable FP2 inhibitors, which are hence potential antiplasmodial agents. A total of 45 drugs were identified, which have positive drug-likeness, no toxic features and good bioavailability. Among these, six drugs showed good binding affinity towards FP2 compared to E64, an epoxide known to inhibit FP2. Notably, two of them, Cefalotin and Cefoxitin, shared the highest MCS with E64, which suggests that they possess similar biological activity as E64. In an investigation using MD for 100 ns, Cefalotin and Cefoxitin showed adequate protein compactness as well as satisfactory complex stability. Overall, these computational approach findings can be applied for designing and developing specific inhibitors or new antimalarial agents for the treatment of malaria infections.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Kanika Verma
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Ayush Kumar Lahariya
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Garima Verma
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
- School of Studies in Microbiology, Jiwaji University, Gwalior, Madhya Pradesh, India
| | - Monika Kumari
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
- Department of Biotechnology, St. Aloysius' (Autonomous) College, Affiliated to Rani Durgawati University, Jabalpur, Madhya Pradesh, Jabalpur, India
| | - Divanshi Gupta
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
- Department of Biological Sciences, Rani Durgawati University, Jabalpur, Madhya Pradesh, India
| | - Neha Maurya
- Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad, Prayagraj, India
| | - Anil Kumar Verma
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
| | - Ashutosh Mani
- Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad, Prayagraj, India
| | | | - Praveen Kumar Bharti
- Division of Vector-Borne Diseases, ICMR-National Institute of Research in Tribal Health, Jabalpur, Madhya Pradesh, India
- Department of Parasite Host Biology, National Institute of Malaria Research, Delhi, India
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Müller J, Hemphill A. Toxoplasma gondii infection: novel emerging therapeutic targets. Expert Opin Ther Targets 2023; 27:293-304. [PMID: 37212443 PMCID: PMC10330558 DOI: 10.1080/14728222.2023.2217353] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 04/24/2023] [Indexed: 05/23/2023]
Abstract
INTRODUCTION Toxoplasmosis constitutes a challenge for public health, animal production, and welfare. So far, only a limited panel of drugs has been marketed for clinical applications. In addition to classical screening, the investigation of unique targets of the parasite may lead to the identification of novel drugs. AREAS COVERED Herein, the authors describe the methodology to identify novel drug targets in Toxoplasma gondii and review the literature with a focus on the last two decades. EXPERT OPINION Over the last two decades, the investigation of essential proteins of T. gondii as potential drug targets has fostered the hope of identifying novel compounds for the treatment of toxoplasmosis. Despite good efficacies in vitro, only a few classes of these compounds are effective in suitable rodent models, and none has cleared the hurdle to applications in humans. This shows that target-based drug discovery is in no way better than classical screening approaches. In both cases, off-target effects and adverse side effects in the hosts must be considered. Proteomics-driven analyses of parasite- and host-derived proteins that physically bind drug candidates may constitute a suitable tool to characterize drug targets, irrespectively of the drug discovery methods.
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Affiliation(s)
- Joachim Müller
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Andrew Hemphill
- Department of Infectious Diseases and Pathobiology, Institute of Parasitology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Usman MA, Salman AA, Ibrahim MA, Furukawa K, Yamasaki K. Biological functions and structural biology of Plasmodium falciparum autophagy-related proteins: The under-explored options for novel antimalarial drug design. Chem Biol Drug Des 2023; 101:1241-1251. [PMID: 36869438 DOI: 10.1111/cbdd.14225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 02/08/2023] [Accepted: 02/28/2023] [Indexed: 03/05/2023]
Abstract
Malaria remains a threat to global public health and the available antimalarial drugs are undermined by side effects and parasite resistance, suggesting an emphasis on new potential targets. Among the novel targets, Plasmodium falciparum autophagy-related proteins (PfAtg) remain a priority. In this paper, we reviewed the existing knowledge on the functions and structural biology of PfAtg including the compounds with inhibitory activity toward P. falciparum Atg8-Atg3 protein-protein interaction (PfAtg8-PfAtg3 PPI). A total of five PfAtg (PfAtg5, PfAtg8, PfAtg12, PfAtg18, and Rab7) were observed to have autophagic and/or non-autophagic roles. Available data showed that PfAtg8 has conserved hydrophobic pockets, which allows it to interact with PfAtg3 to form PfAtg8-PfAtg3 PPI. Additionally, 2-bromo-N-(4-pyridin-2-yl-1,3-thiazol-2-yl) benzamide was identified as the most powerful inhibitor of PfAtg8-PfAtg3 PPI. Due to the dearth of knowledge in this field, we hope that the article would open an avenue to further research on the remaining PfAtg as possible drug candidates.
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Affiliation(s)
| | | | | | - Koji Furukawa
- Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Kazuhiko Yamasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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Comparative Degradome Analysis of the Bovine Piroplasmid Pathogens Babesia bovis and Theileria annulata. Pathogens 2023; 12:pathogens12020237. [PMID: 36839509 PMCID: PMC9965338 DOI: 10.3390/pathogens12020237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
Babesia bovis and Theileria annulata are tick-borne hemoprotozoans that impact bovine health and are responsible for considerable fatalities in tropical and subtropical regions around the world. Both pathogens infect the same vertebrate host, are closely related, and contain similar-sized genomes; however, they differ in invertebrate host specificity, absence vs. presence of a schizont stage, erythrocyte invasion mechanism, and transovarial vs. transstadial transmission. Phylogenetic analysis and bidirectional best hit (BBH) identified a similar number of aspartic, metallo, and threonine proteinases and nonproteinase homologs. In contrast, a considerably increased number of S54 serine rhomboid proteinases and S9 nonproteinase homologs were identified in B. bovis, whereas C1A cysteine proteinases and A1 aspartic nonproteinase homologs were found to be expanded in T. annulata. Furthermore, a single proteinase of families S8 (subtilisin-like protein) and C12 (ubiquitin carboxyl-terminal hydrolase), as well as four nonproteinase homologs, one with dual domains M23-M23 and three with S9-S9, were exclusively present in B. bovis. Finally, a pronounced difference in species-specific ancillary domains was observed between both species. We hypothesize that the observed degradome differences represent functional correlates of the dissimilar life history features of B. bovis and T. annulata. The presented improved classification of piroplasmid proteinases will facilitate an informed choice for future in-depth functional studies.
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Frasse PM, Miller JJ, Polino AJ, Soleimani E, Zhu JS, Jakeman DL, Jez JM, Goldberg DE, Odom John AR. Enzymatic and structural characterization of HAD5, an essential phosphomannomutase of malaria-causing parasites. J Biol Chem 2022; 298:101550. [PMID: 34973333 PMCID: PMC8808168 DOI: 10.1016/j.jbc.2021.101550] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/05/2022] Open
Abstract
The malaria-causing parasite Plasmodium falciparum is responsible for over 200 million infections and 400,000 deaths per year. At multiple stages during its complex life cycle, P. falciparum expresses several essential proteins tethered to its surface by glycosylphosphatidylinositol (GPI) anchors, which are critical for biological processes such as parasite egress and reinvasion of host red blood cells. Targeting this pathway therapeutically has the potential to broadly impact parasite development across several life stages. Here, we characterize an upstream component of parasite GPI anchor biosynthesis, the putative phosphomannomutase (PMM) (EC 5.4.2.8), HAD5 (PF3D7_1017400). We confirmed the PMM and phosphoglucomutase activities of purified recombinant HAD5 by developing novel linked enzyme biochemical assays. By regulating the expression of HAD5 in transgenic parasites with a TetR-DOZI-inducible knockdown system, we demonstrated that HAD5 is required for malaria parasite egress and erythrocyte reinvasion, and we assessed the role of HAD5 in GPI anchor synthesis by autoradiography of radiolabeled glucosamine and thin layer chromatography. Finally, we determined the three-dimensional X-ray crystal structure of HAD5 and identified a substrate analog that specifically inhibits HAD5 compared to orthologous human PMMs in a time-dependent manner. These findings demonstrate that the GPI anchor biosynthesis pathway is exceptionally sensitive to inhibition in parasites and that HAD5 has potential as a specific, multistage antimalarial target.
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Affiliation(s)
- Philip M Frasse
- Division of Infectious Diseases, Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Justin J Miller
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Alexander J Polino
- Division of Infectious Diseases, Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ebrahim Soleimani
- College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Chemistry, Razi University, Kermanshah, Iran
| | - Jian-She Zhu
- College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David L Jakeman
- College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Joseph M Jez
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Daniel E Goldberg
- Division of Infectious Diseases, Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Audrey R Odom John
- Division of Infectious Diseases, Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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Gao X, Yin J, Wang D, Li X, Zhang Y, Wang C, Zhang Y, Zhu G. Discovery of New Microneme Proteins in Cryptosporidium parvum and Implication of the Roles of a Rhomboid Membrane Protein (CpROM1) in Host-Parasite Interaction. Front Vet Sci 2021; 8:778560. [PMID: 34966810 PMCID: PMC8710574 DOI: 10.3389/fvets.2021.778560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/12/2021] [Indexed: 01/25/2023] Open
Abstract
Apicomplexan parasites possess several unique secretory organelles, including rhoptries, micronemes, and dense granules, which play critical roles in the invasion of host cells. The molecular content of these organelles and their biological roles have been well-studied in Toxoplasma and Plasmodium, but are underappreciated in Cryptosporidium, which contains many parasites of medical and veterinary importance. Only four proteins have previously been identified or proposed to be located in micronemes, one of which, GP900, was confirmed using immunogold electron microscopy (IEM) to be present in the micronemes of intracellular merozoites. Here, we report on the discovery of four new microneme proteins (MICs) in the sporozoites of the zoonotic species C. parvum, identified using immunofluorescence assay (IFA). These proteins are encoded by cgd3_980, cgd1_3550, cgd1_3680, and cgd2_1590. The presence of the protein encoded by cgd3_980 in sporozoite micronemes was further confirmed using IEM. Cgd3_980 encodes one of the three C. parvum rhomboid peptidases (ROMs) and is, thus, designated CpROM1. IEM also confirmed the presence of CpROM1 in the micronemes of intracellular merozoites, parasitophorous vacuole membranes (PVM), and feeder organelles (FO). CpROM1 was enriched in the pellicles and concentrated at the host cell–parasite interface during the invasion of sporozoites and its subsequent transformation into trophozoites. CpROM1 transcript levels were also higher in oocysts and excysted sporozoites than in the intracellular parasite stages. These observations indicate that CpROM1, an intramembrane peptidase with membrane proteolytic activity, is involved in host–parasite interactions, including invasion and proteostasis of PVM and FO.
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Affiliation(s)
- Xin Gao
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jigang Yin
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Dongqiang Wang
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xiaohui Li
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Ying Zhang
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Chenchen Wang
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yuanyuan Zhang
- Electron Microscopy Core Facility, The Institute of Zoonosis, Jilin University, Changchun, China
| | - Guan Zhu
- Key Laboratory of Zoonosis Research of the Ministry of Education, The Institute of Zoonosis, and the College of Veterinary Medicine, Jilin University, Changchun, China
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The repertoire of serine rhomboid proteases of piroplasmids of importance to animal and human health. Int J Parasitol 2021; 51:455-462. [PMID: 33610524 DOI: 10.1016/j.ijpara.2020.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/24/2020] [Accepted: 10/27/2020] [Indexed: 02/07/2023]
Abstract
Babesia, Theileria and Cytauxzoon are tick-borne apicomplexan protozoans of the order Piroplasmida, notorious for the diseases they cause in livestock, pets and humans. Host cell invasion is their Achilles heel, allowing for the development of drug or vaccine-based therapies. In other apicomplexans, cleavage of the transmembrane domain of adhesins by the serine rhomboid proteinase ROM4 is required for successful completion of invasion. In this study, we record and classify the rhomboid repertoire encoded in the genomes of 10 piroplasmid species pertaining to the lineages Babesia sensu stricto (s.s., Clade VI), Theileria sensu stricto (Clade IV), Theileria equi (Clade IV), Cytauxzoon felis (Clade IIIb) and Babesia microti (Clade I), as defined by Schnittger et al. (2012). Fifty-six piroplasmid rhomboid-like proteins were assigned by phylogenetic analysis and bidirectional best hit to the ROM4, ROM6, ROM7 or ROM8 groups, and their crucial motifs for conformation and function were identified. Forty-four of these rhomboids had either been incorrectly classified or misannotated. Babesia s.s. encode five or three ROM4 proteinase paralogs, whereas the remaining piroplasmids encode two ROM4 paralogs. All piroplasmids encode a single ROM6, ROM7 and ROM8. Thus, an increased paralog number of ROM4 is the only feature distinguishing Babesia s.s. from other piroplasmid lineages. Piroplasmid ROM6 is related to the mammalian mitochondrial rhomboid and, accordingly, N-terminal mitochondrial targeting signal sequences was found in some cases. ROM6 is the only rhomboid encoded by piroplasmids that is ubiquitous in other organisms. ROM8 represents a pseudoproteinase that is highly conserved between studied piroplasmids, suggesting that it is important in regulatory functions. ROM4, ROM6, ROM7 and ROM8 are exclusively present in Aconoidasida, which comprises piroplasmids and Plasmodium, suggesting a relevant functional role in erythrocyte invasion. The correct classification and designation of piroplasmid rhomboids presented in this study facilitates an informed choice for future in-depth study of their functions.
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Rhomboid protein 2 of Eimeria maxima provided partial protection against infection by homologous species. Vet Res 2021; 52:29. [PMID: 33602319 PMCID: PMC7893758 DOI: 10.1186/s13567-020-00886-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 12/23/2020] [Indexed: 11/24/2022] Open
Abstract
Rhomboid-like proteases (ROMs) are considered as new candidate antigens for developing new-generation vaccines due to their important role involved in the invasion of apicomplexan protozoa. In prior works, we obtained a ROM2 sequence of Eimeria maxima (EmROM2). This study was conducted to evaluate the immunogenicity and protective efficacy of EmROM2 recombinant protein (rEmROM2) and EmROM2 DNA (pVAX1-EmROM2) against infection by Eimeria maxima (E. maxima). Firstly, Western blot assay was conducted to analyze the immunogenicity of rEmROM2. The result showed that rEmROM2 was recognized by chicken anti-E. maxima serum. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot assay revealed apparent transcription and expression of EmROM2 at the injection site. qRT-PCR (quantitative real-time PCR), flow cytometry and indirect ELISA indicated that vaccination with rEmROM2 or EmROM2 DNA significantly upregulated the transcription level of cytokines (IFN-γ, IL-2, IL-4, IL-10, IL-17, TGF-β and TNF SF15), the proportion of CD8+ and CD4+ T lymphocytes and serum IgG antibody response. Ultimately, a vaccination-challenge trial was performed to evaluate the protective efficacy of rEmROM2 and pVAX1-EmROM2 against E. maxima. The result revealed that vaccination with rEmROM2 or pVAX1-EmROM2 significantly alleviated enteric lesions, weight loss, and reduced oocyst output caused by challenge infection of E. maxima, and provided anticoccidial index (ACI) of more than 160, indicating partial protection against E. maxima. In summary, vaccination with rEmROM2 or pVAX1-EmROM2 activated notable humoral and cell-mediated immunity and provided partial protection against E. maxima. These results demonstrated that EmROM2 protein and DNA are promising vaccine candidates against E. maxima infection.
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Kinetic characterization of a novel cysteine peptidase from the protozoan Babesia bovis, a potential target for drug design. Biochimie 2020; 179:127-134. [PMID: 32946988 DOI: 10.1016/j.biochi.2020.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 09/12/2020] [Indexed: 11/22/2022]
Abstract
C1A cysteine peptidases have been shown to play an important role during apicomplexan invasion and egress of host red blood cells (RBCs) and therefore have been exploited as targets for drug development, in which peptidase specificity is deterministic. Babesia bovis genome is currently available and from the 17 putative cysteine peptidases annotated four belong to the C1A subfamily. In this study, we describe the biochemical characterization of a C1A cysteine peptidase, named here BbCp (B. bovis cysteine peptidase) and evaluate its possible participation in the parasite asexual cycle in host RBCs. The recombinant protein was obtained in bacterial inclusion bodies and after a refolding process, presented typical kinetic features of the cysteine peptidase family, enhanced activity in the presence of a reducing agent, optimum pH between 6.5 and 7.0 and was inhibited by cystatins from R. microplus. Moreover, rBbCp substrate specificity evaluation using a peptide phage display library showed a preference for Val > Leu > Phe. Finally, antibodies anti-rBbCp were able to interfere with B. bovis growth in vitro, which highlights the BbCp as a potential target for drug design.
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Host Cytoskeleton Remodeling throughout the Blood Stages of Plasmodium falciparum. Microbiol Mol Biol Rev 2019; 83:83/4/e00013-19. [PMID: 31484690 DOI: 10.1128/mmbr.00013-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The asexual intraerythrocytic development of Plasmodium falciparum, causing the most severe form of human malaria, is marked by extensive host cell remodeling. Throughout the processes of invasion, intracellular development, and egress, the erythrocyte membrane skeleton is remodeled by the parasite as required for each specific developmental stage. The remodeling is facilitated by a plethora of exported parasite proteins, and the erythrocyte membrane skeleton is the interface of most of the observed interactions between the parasite and host cell proteins. Host cell remodeling has been extensively described and there is a vast body of information on protein export or the description of parasite-induced structures such as Maurer's clefts or knobs on the host cell surface. Here we specifically review the molecular level of each host cell-remodeling step at each stage of the intraerythrocytic development of P. falciparum We describe key events, such as invasion, knob formation, and egress, and identify the interactions between exported parasite proteins and the host cell cytoskeleton. We discuss each remodeling step with respect to time and specific requirement of the developing parasite to explain host cell remodeling in a stage-specific manner. Thus, we highlight the interaction with the host membrane skeleton as a key event in parasite survival.
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12
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Foroutan M, Zaki L, Tavakoli S, Soltani S, Taghipour A, Ghaffarifar F. Rhomboid antigens are promising targets in the vaccine development against Toxoplasma gondii. EXCLI JOURNAL 2019; 18:259-272. [PMID: 31337999 PMCID: PMC6635731 DOI: 10.17179/excli2018-1993] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 04/17/2019] [Indexed: 01/10/2023]
Abstract
Toxoplasma gondii (T. gondii) is an obligate intracellular parasite with worldwide distribution. It is estimated that near one-third of the people around the globe are latently seropositive for the parasite. Since the current common drugs are incapable in the elimination of parasites within tissue cysts, the development of an effective vaccine has high priority for researchers to limit the infection. During recent years, non-stop efforts of scientists have made great progress in the identification and development of T. gondii candidate vaccines. However, there is a lack of a commercially licensed vaccine for human application yet. Rhomboid proteases (ROMs) are a class of serine proteases that have an important role in the invasion of the parasites that can be considered as a new target for vaccine strategy. They also play critical roles in mitochondrial fusion and growth factor signaling, allowing the parasite to completely enter into the host cell. In the current review, we have summarized the recent progress regarding the development of ROM-based vaccines against acute and chronic T. gondii infection in animal models.
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Affiliation(s)
- Masoud Foroutan
- Abadan School of Medical Sciences, Abadan, Iran.,Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Leila Zaki
- Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Sanaz Tavakoli
- Department of Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | - Ali Taghipour
- Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Fatemeh Ghaffarifar
- Department of Parasitology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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13
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Musyoka TM, Njuguna JN, Tastan Bishop Ö. Comparing sequence and structure of falcipains and human homologs at prodomain and catalytic active site for malarial peptide based inhibitor design. Malar J 2019; 18:159. [PMID: 31053072 PMCID: PMC6500056 DOI: 10.1186/s12936-019-2790-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 04/23/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Falcipains are major cysteine proteases of Plasmodium falciparum involved in haemoglobin degradation and remain attractive anti-malarial drug targets. Several inhibitors against these proteases have been identified, yet none of them has been approved for malaria treatment. Other Plasmodium species also possess highly homologous proteins to falcipains. For selective therapeutic targeting, identification of sequence and structure differences with homologous human cathepsins is necessary. The substrate processing activity of these proteins is tightly controlled via a prodomain segment occluding the active site which is chopped under low pH conditions exposing the catalytic site. Current work characterizes these proteases to identify residues mediating the prodomain regulatory function for the design of peptide based anti-malarial inhibitors. METHODS Sequence and structure variations between prodomain regions of plasmodial proteins and human cathepsins were determined using in silico approaches. Additionally, evolutionary clustering of these proteins was evaluated using phylogenetic analysis. High quality partial zymogen protein structures were modelled using homology modelling and residue interaction analysis performed between the prodomain segment and mature domain to identify key interacting residues between these two domains. The resulting information was used to determine short peptide sequences which could mimic the inherent regulatory function of the prodomain regions. Through flexible docking, the binding affinity of proposed peptides on the proteins studied was evaluated. RESULTS Sequence, evolutionary and motif analyses showed important differences between plasmodial and human proteins. Residue interaction analysis identified important residues crucial for maintaining prodomain integrity across the different proteins as well as the pro-segment responsible for inhibitory mechanism. Binding affinity of suggested peptides was highly dependent on their residue composition and length. CONCLUSIONS Despite the conserved structural and catalytic mechanism between human cathepsins and plasmodial proteases, current work revealed significant differences between the two protein groups which may provide valuable information for selective anti-malarial inhibitor development. Part of this study aimed to design peptide inhibitors based on endogenous inhibitory portions of protease prodomains as a novel aspect. Even though peptide inhibitors may not be practical solutions to malaria at this stage, the approach followed and results offer a promising means to find new malarial inhibitors.
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Affiliation(s)
- Thommas Mutemi Musyoka
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown, 6140, South Africa
| | - Joyce Njoki Njuguna
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown, 6140, South Africa
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Grahamstown, 6140, South Africa.
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14
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Melo PM, El Chamy Maluf S, Azevedo MF, Paschoalin T, Budu A, Bagnaresi P, Henrique-Silva F, Soares-Costa A, Gazarini ML, Carmona AK. Inhibition of Plasmodium falciparum cysteine proteases by the sugarcane cystatin CaneCPI-4. Parasitol Int 2018; 67:233-236. [DOI: 10.1016/j.parint.2017.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 10/03/2017] [Accepted: 12/25/2017] [Indexed: 10/18/2022]
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15
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Targeted Phenotypic Screening in Plasmodium falciparum and Toxoplasma gondii Reveals Novel Modes of Action of Medicines for Malaria Venture Malaria Box Molecules. mSphere 2018; 3:mSphere00534-17. [PMID: 29359192 PMCID: PMC5770543 DOI: 10.1128/msphere.00534-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 12/20/2017] [Indexed: 01/23/2023] Open
Abstract
The Malaria Box collection includes 400 chemically diverse small molecules with documented potency against malaria parasite growth, but the underlying modes of action are largely unknown. Using complementary phenotypic screens against Plasmodium falciparum and Toxoplasma gondii, we report phenotype-specific hits based on inhibition of overall parasite growth, apicoplast segregation, and egress or host invasion, providing hitherto unavailable insights into the possible mechanisms affected. First, the Malaria Box library was screened against tachyzoite stage T. gondii and the half-maximal effective concentrations (EC50s) of molecules showing ≥80% growth inhibition at 10 µM were determined. Comparison of the EC50s for T. gondii and P. falciparum identified a subset of 24 molecules with nanomolar potency against both parasites. Thirty molecules that failed to induce acute growth inhibition in T. gondii tachyzoites in a 2-day assay caused delayed parasite death upon extended exposure, with at least three molecules interfering with apicoplast segregation during daughter cell formation. Using flow cytometry and microscopy-based examinations, we prioritized 26 molecules with the potential to inhibit host cell egress/invasion during asexual developmental stages of P. falciparum. None of the inhibitors affected digestive vacuole integrity, ruling out a mechanism mediated by broadly specific protease inhibitor activity. Interestingly, five of the plasmodial egress inhibitors inhibited ionophore-induced egress of T. gondii tachyzoites. These findings highlight the advantage of comparative and targeted phenotypic screens in related species as a means to identify lead molecules with a conserved mode of action. Further work on target identification and mechanism analysis will facilitate the development of antiparasitic compounds with cross-species efficacy. IMPORTANCE The phylum Apicomplexa includes many human and animal pathogens, such as Plasmodium falciparum (human malaria) and Toxoplasma gondii (human and animal toxoplasmosis). Widespread resistance to current antimalarials and the lack of a commercial vaccine necessitate novel pharmacological interventions with distinct modes of action against malaria. For toxoplasmosis, new drugs to effectively eliminate tissue-dwelling latent cysts of the parasite are needed. The Malaria Box antimalarial collection, managed and distributed by the Medicines for Malaria Venture, includes molecules of novel chemical classes with proven antimalarial efficacy. Using targeted phenotypic assays of P. falciparum and T. gondii, we have identified a subset of the Malaria Box molecules as potent inhibitors of plastid segregation and parasite invasion and egress, thereby providing early insights into their probable mode of action. Five molecules that inhibit the egress of both parasites have been identified for further mechanistic studies. Thus, the approach we have used to identify novel molecules with defined modes of action in multiple parasites can expedite the development of pan-active antiparasitic agents.
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16
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Cysteine protease 30 (CP30) contributes to adhesion and cytopathogenicity in feline Tritrichomonas foetus. Vet Parasitol 2017; 244:114-122. [DOI: 10.1016/j.vetpar.2017.07.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/29/2017] [Accepted: 07/31/2017] [Indexed: 12/30/2022]
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17
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Mastan BS, Narwal SK, Dey S, Kumar KA, Mishra S. Plasmodium berghei plasmepsin VIII is essential for sporozoite gliding motility. Int J Parasitol 2017; 47:239-245. [PMID: 28192122 DOI: 10.1016/j.ijpara.2016.11.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/21/2016] [Accepted: 11/28/2016] [Indexed: 01/03/2023]
Abstract
Plasmodium aspartic proteases, termed plasmepsins (PMs) play many critical roles such as haemoglobin degradation, cleavage of PEXEL proteins and sporozoite development in the parasite life cycle. Most of the plasmepsins are well characterized, however the role of PM VIII in Plasmodium remains unknown. Here, we elucidate the functions of PM VIII (PBANKA_132910) in the rodent malaria parasite Plasmodium berghei (Pb). By targeted gene deletion, we show that PbPM VIII is critical for sporozoite egress from an oocyst and gliding motility, which is a prerequisite for the invasion of salivary glands and subsequent transmission to the vertebrate host.
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Affiliation(s)
- Babu S Mastan
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Sunil Kumar Narwal
- Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Sandeep Dey
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Kota Arun Kumar
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
| | - Satish Mishra
- Division of Parasitology, CSIR-Central Drug Research Institute, Lucknow 226031, India.
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18
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Zhang NZ, Xu Y, Wang M, Petersen E, Chen J, Huang SY, Zhu XQ. Protective efficacy of two novel DNA vaccines expressing Toxoplasma gondii rhomboid 4 and rhomboid 5 proteins against acute and chronic toxoplasmosis in mice. Expert Rev Vaccines 2015; 14:1289-97. [PMID: 26111968 DOI: 10.1586/14760584.2015.1061938] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES To evaluate the protective efficacy of two novel DNA vaccines expressing Toxoplasma gondii rhomboid 4 (ROM4) and rhomboid 5 (ROM5) proteins against acute and chronic toxoplasmosis. METHODS DNA vaccines (pVAX-TgROM5 and pVAX-TgROM4) were constructed and their immunogenicity evaluated in Kunming mice. RESULTS Mice vaccinated with pVAX-TgROM5 or pVAX-TgROM4 elicited strong Th1-type humoral and cellular responses, with higher level of IgG antibody titers (the predominance of IgG2a production), and increased levels of CD4(+) and CD8(+) T cells and cytokines IFN-γ, IL-2, IL-12 (p70) and IL-23. Mice vaccinated with pVAX-TgROM5 (11 days) showed a significantly longer survival time compared with controls (8 days) (p < 0.05) after lethal challenge. Brain cyst numbers of mice vaccinated with pVAX-TgROM5 and pVAX-TgROM4 reduced significantly (p < 0.05) (72.04 and 44.08%, respectively) compared with control groups after chronic challenge. CONCLUSION The pVAX-TgROM5 showed a better protective efficacy against acute and chronic toxoplasmosis compared to pVAX-TgROM4.
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Affiliation(s)
- Nian-Zhang Zhang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province 730046, PR China
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19
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Rastew E, Morf L, Singh U. Entamoeba histolytica rhomboid protease 1 has a role in migration and motility as validated by two independent genetic approaches. Exp Parasitol 2015; 154:33-42. [PMID: 25889553 DOI: 10.1016/j.exppara.2015.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/24/2015] [Accepted: 04/08/2015] [Indexed: 11/25/2022]
Abstract
Rhomboid proteins represent a recently discovered family of intramembrane proteases present in a broad range of organisms and with increasing links to human diseases. The enteric parasite Entamoeba histolytica has evolved multiple mechanisms to adapt to the human host environment and establish infection. Our recent studies identified EhROM1 as a functional E. histolytica rhomboid protease with roles in adhesion to and phagocytosis of host cells. Since those studies were performed in a non-virulent strain, roles in parasite virulence could not be assessed. We focused this study on the comparison and validation of two genetic manipulation techniques: overexpression of a dominant-negative catalytic mutant of EhROM1 and knock down of EhROM1 using a RNAi-based silencing approach followed by functional studies of phenotypic analyses in virulent parasites. Both the EhROM1 catalytic mutant and parasites with EhROM1 downregulation were reduced in cytotoxicity, hemolytic activity, and directional and non-directional transwell migration. Importantly, the role for EhROM1 in cell migration mimics similar roles for rhomboid proteases from mammalian and apicomplexan systems. However, the EhROM1 catalytic mutant and EhROM1 downregulation parasites had different phenotypes for erythrophagocytosis, while complement resistance was not affected in either strain. In summary, in this study we genetically manipulated E. histolytica rhomboid protease EhROM1 by two different approaches and identified similarly attenuated phenotypes by both approaches, suggesting a novel role for EhROM1 in amebic motility.
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Affiliation(s)
- Elena Rastew
- Department of Internal Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Laura Morf
- Department of Internal Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Upinder Singh
- Department of Internal Medicine, Stanford University School of Medicine, Stanford, CA, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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20
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Repnik U, Gangopadhyay P, Bietz S, Przyborski JM, Griffiths G, Lingelbach K. The apicomplexan parasite Babesia divergens internalizes band 3, glycophorin A and spectrin during invasion of human red blood cells. Cell Microbiol 2015; 17:1052-68. [PMID: 25628009 DOI: 10.1111/cmi.12422] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 01/14/2015] [Accepted: 01/15/2015] [Indexed: 12/21/2022]
Abstract
Plasmodium falciparum invades human red blood cells (RBC), while Babesia divergens infects bovine and, occasionally, human RBC. The mammalian RBC is normally unable to endocytose or phagocytose and the events leading to invasion are incompletely understood. Initially, both parasites are surrounded by the RBC plasma membrane-derived parasitophorous vacuolar membrane (PVM) that is formed during invasion. In P. falciparum-infected RBC, the PVM persists at least until parasite replication is completed whereas it has been proposed that the B. divergens PVM is disintegrated soon upon invasion. Here, we have used a B. divergens strain adapted to human RBC to investigate the formation and fate of the PVM. Using ultrastructural analysis and whole-mount or on-section immunofluorescence and immunogold labelling, we demonstrate that the initial vacuolar membrane is formed from protein and lipid components of the RBC plasma membrane. Integral membrane proteins band 3 and glycophorin A and the cytoskeletal protein spectrin are associated with the PVM of the B. divergens, but are absent from the PVM of P. falciparum at the ring or the trophozoite stage. Our results provide evidence that the biophysical properties of the RBC cytoskeleton per se do not preclude the internalization of cytoskeletal proteins by invading parasites.
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Affiliation(s)
- Urska Repnik
- Department of Biosciences, University of Oslo, Blindernveien 31, Oslo, 0316, Norway
| | - Preetish Gangopadhyay
- Department of Parasitology, Philipps University Marburg, Karl-von-Frisch-Strasse 8, Marburg, 35043, Germany
| | - Sven Bietz
- Department of Parasitology, Philipps University Marburg, Karl-von-Frisch-Strasse 8, Marburg, 35043, Germany
| | - Jude M Przyborski
- Department of Parasitology, Philipps University Marburg, Karl-von-Frisch-Strasse 8, Marburg, 35043, Germany
| | - Gareth Griffiths
- Department of Biosciences, University of Oslo, Blindernveien 31, Oslo, 0316, Norway
| | - Klaus Lingelbach
- Department of Parasitology, Philipps University Marburg, Karl-von-Frisch-Strasse 8, Marburg, 35043, Germany
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21
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Lehmann C, Heitmann A, Mishra S, Burda PC, Singer M, Prado M, Niklaus L, Lacroix C, Ménard R, Frischknecht F, Stanway R, Sinnis P, Heussler V. A cysteine protease inhibitor of plasmodium berghei is essential for exo-erythrocytic development. PLoS Pathog 2014; 10:e1004336. [PMID: 25166051 PMCID: PMC4148452 DOI: 10.1371/journal.ppat.1004336] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 07/08/2014] [Indexed: 11/18/2022] Open
Abstract
Plasmodium parasites express a potent inhibitor of cysteine proteases (ICP) throughout their life cycle. To analyze the role of ICP in different life cycle stages, we generated a stage-specific knockout of the Plasmodium berghei ICP (PbICP). Excision of the pbicb gene occurred in infective sporozoites and resulted in impaired sporozoite invasion of hepatocytes, despite residual PbICP protein being detectable in sporozoites. The vast majority of these parasites invading a cultured hepatocyte cell line did not develop to mature liver stages, but the few that successfully developed hepatic merozoites were able to initiate a blood stage infection in mice. These blood stage parasites, now completely lacking PbICP, exhibited an attenuated phenotype but were able to infect mosquitoes and develop to the oocyst stage. However, PbICP-negative sporozoites liberated from oocysts exhibited defective motility and invaded mosquito salivary glands in low numbers. They were also unable to invade hepatocytes, confirming that control of cysteine protease activity is of critical importance for sporozoites. Importantly, transfection of PbICP-knockout parasites with a pbicp-gfp construct fully reversed these defects. Taken together, in P. berghei this inhibitor of the ICP family is essential for sporozoite motility but also appears to play a role during parasite development in hepatocytes and erythrocytes.
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Affiliation(s)
| | - Anna Heitmann
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Satish Mishra
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | | | - Mirko Singer
- University of Heidelberg Medical School, Heidelberg, Germany
| | - Monica Prado
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Livia Niklaus
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Céline Lacroix
- Institute Pasteur, Unité de Biologie et Génétique du Paludisme, Paris, France
| | - Robert Ménard
- Institute Pasteur, Unité de Biologie et Génétique du Paludisme, Paris, France
| | | | - Rebecca Stanway
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Photini Sinnis
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Volker Heussler
- Institute of Cell Biology, University of Bern, Bern, Switzerland
- * E-mail:
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22
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Melo PM, Bagnaresi P, Paschoalin T, Hirata IY, Gazarini ML, Carmona AK. Plasmodium falciparum proteases hydrolyze plasminogen, generating angiostatin-like fragments. Mol Biochem Parasitol 2014; 193:45-54. [DOI: 10.1016/j.molbiopara.2014.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/22/2014] [Accepted: 01/25/2014] [Indexed: 12/27/2022]
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23
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Ma D, Gao M, Li J, Ma C, Li G. Construction of novel cytokine by fusion of chicken IL-2 signal peptide to mature chicken IL-15 and comparison of the adjuvant effects by DNA immunization against Eimeria challenge. Vet Immunol Immunopathol 2013; 156:114-20. [PMID: 24139475 DOI: 10.1016/j.vetimm.2013.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 08/28/2013] [Accepted: 09/12/2013] [Indexed: 10/26/2022]
Abstract
A novel fusion cytokine was constructed by replacing signal peptide (SP) of chicken IL-15 (ChIL-15) with SP of chicken IL-2 (ChIL-2). The fusion cytokine (NChIL-15) was cloned into the expression vector pcDNA3.1(+) to generate pcDNA-NChIL-15. An animal experiment was carried out to evaluate the adjuvant effects of NChIL-15 on DNA vaccine pcDNA-3-1E against Eimeria acervulina challenge. The mRNA profiles of ChIL-2 and ChIFN-γ in spleen were characterized by means of real-time PCR. The recombinant positive eukaryotic expression plasmid pcDNA-NChIL-15 were constructed successfully. The protective effects provided by co-immunization with 100 μg pcDNA-3-1E and 50 μg pcDNA-NChIL-15, measured by relative body weight gain (BWG), average lesion score in duodenum and oocyst decrease ratio, showed no significant difference with 50 μg pcDNA-ChIL-15 as an adjuvant on day 6 post infection (PI). However, chickens co-immunized with pcDNA-3-1E and pcDNA-NChIL-15 exhibited significant upregulated level of ChIL-2 and ChIFN-γ transcripts in spleen. Our original data suggests the constructed novel cytokine NChIL-15 could be a potential adjuvant used to enhance the immune protective effects, although the optimized dosage need to be explored further.
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Affiliation(s)
- Dexing Ma
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang, China
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24
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Bouillon A, Giganti D, Benedet C, Gorgette O, Pêtres S, Crublet E, Girard-Blanc C, Witkowski B, Ménard D, Nilges M, Mercereau-Puijalon O, Stoven V, Barale JC. In Silico screening on the three-dimensional model of the Plasmodium vivax SUB1 protease leads to the validation of a novel anti-parasite compound. J Biol Chem 2013; 288:18561-73. [PMID: 23653352 PMCID: PMC3689996 DOI: 10.1074/jbc.m113.456764] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/03/2013] [Indexed: 12/12/2022] Open
Abstract
Widespread drug resistance calls for the urgent development of new antimalarials that target novel steps in the life cycle of Plasmodium falciparum and Plasmodium vivax. The essential subtilisin-like serine protease SUB1 of Plasmodium merozoites plays a dual role in egress from and invasion into host erythrocytes. It belongs to a new generation of attractive drug targets against which specific potent inhibitors are actively searched. We characterize here the P. vivax SUB1 enzyme and show that it displays a typical auto-processing pattern and apical localization in P. vivax merozoites. To search for small PvSUB1 inhibitors, we took advantage of the similarity of SUB1 with bacterial subtilisins and generated P. vivax SUB1 three-dimensional models. The structure-based virtual screening of a large commercial chemical compounds library identified 306 virtual best hits, of which 37 were experimentally confirmed inhibitors and 5 had Ki values of <50 μM for PvSUB1. Interestingly, they belong to different chemical families. The most promising competitive inhibitor of PvSUB1 (compound 2) was equally active on PfSUB1 and displayed anti-P. falciparum and Plasmodium berghei activity in vitro and in vivo, respectively. Compound 2 inhibited the endogenous PfSUB1 as illustrated by the inhibited maturation of its natural substrate PfSERA5 and inhibited parasite egress and subsequent erythrocyte invasion. These data indicate that the strategy of in silico screening of three-dimensional models to select for virtual inhibitors combined with stringent biological validation successfully identified several inhibitors of the PvSUB1 enzyme. The most promising hit proved to be a potent cross-inhibitor of PlasmodiumSUB1, laying the groundwork for the development of a globally active small compound antimalarial.
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Affiliation(s)
- Anthony Bouillon
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - David Giganti
- the Institut Pasteur, Unité de Bioinformatique Structurale, Département de Biologie Structurale et Chimie, F-75015 Paris, France
- CNRS, UMR3258, F-75015 Paris, France
| | - Christophe Benedet
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Olivier Gorgette
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - Stéphane Pêtres
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Elodie Crublet
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Christine Girard-Blanc
- the Institut Pasteur, Proteopole, Département de Biologie Structurale et Chimie, F-75015 Paris, France
| | - Benoit Witkowski
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Didier Ménard
- the Pasteur Institute of Cambodia, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Michael Nilges
- the Institut Pasteur, Unité de Bioinformatique Structurale, Département de Biologie Structurale et Chimie, F-75015 Paris, France
- CNRS, UMR3258, F-75015 Paris, France
| | - Odile Mercereau-Puijalon
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
| | - Véronique Stoven
- the Center for Computational Biology, Mines-ParisTech, Fontainebleau F-77300 France, and
- the Institut Curie, INSERM U900, F-75248 Paris, France
| | - Jean-Christophe Barale
- From the Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Département de Parasitologie et de Mycologie, F-75015 Paris, France
- CNRS, URA2581, F-75015 Paris, France
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Liu Y, Zheng J, Li J, Gong P, Zhang X. Protective immunity induced by a DNA vaccine encoding Eimeria tenella rhomboid against homologous challenge. Parasitol Res 2012; 112:251-7. [PMID: 23052765 DOI: 10.1007/s00436-012-3132-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 09/18/2012] [Indexed: 11/29/2022]
Abstract
Rhomboid protein in Apicomplexa was associated with the process of host cell invasion. To evaluate the potential of the protein in eliciting protective immunity against challenge, a DNA vaccine pVAX1-Rho encoding Eimeria tenella rhomboid was constructed. Recombinant protein was expressed in Hela cells and verified by indirect immunofluorescence and western blotting analysis. In vivo experiments, 1-week-old chickens were randomly divided into three groups. Experimental group of chickens were immunized with DNA vaccines while control group of chickens were injected with pVAX1 plasmid alone or sterile water. Two weeks following the booster dose, all chickens were inoculated orally with 5 × 10(4) sporulated oocysts of E. tenella. The host immunity and protective efficacy of this vaccine against E. tenella challenge in broilers were evaluated. Results showed that specific antibody, the levels of interleukin-2 (IL-2), interferon-γ (IFN-γ), and the percentages of CD4(+) and CD8(+) T lymphocyte cells were significantly increased in the pVAX1-Rho group. Challenge experiments demonstrated that pVAX1-Rho vaccination could reduce oocyst excretion, decrease cecal lesion, increase bodyweight gains and provide chickens with oocysts decrease ratio around 75.8 %. These results suggest that the pVAX1-Rho was able to induce humoral and cellular responses and generate protective immunity against E. tenella infection.
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Affiliation(s)
- Yingli Liu
- College of Animal Science and Veterinary Medicine, Jilin University, 5333 Xi'an Road, Changchun, 130062, People's Republic of China.
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Quinolylhydrazones as novel inhibitors of Plasmodium falciparum serine protease PfSUB1. Bioorg Med Chem Lett 2012; 22:5317-21. [PMID: 22796182 DOI: 10.1016/j.bmcl.2012.06.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 06/07/2012] [Accepted: 06/10/2012] [Indexed: 11/22/2022]
Abstract
Plasmodium falciparum subtilisin-like protease 1 (PfSUB1) is a serine protease that plays key roles in the egress of the parasite from red blood cells and in preparing the released merozoites for the subsequent invasion of new erythrocytes. The development of potent and selective PfSUB1 inhibitors could pave the way to the discovery of potential antimalarial drugs endowed with an innovative mode of action and consequently able to overcome the current problems of resistance to established chemotherapies. Through the screening of a proprietary library of compounds against PfSUB1, we identified hydrazone 2 as a hit compound. Here we report a preliminary investigation of the structure-activity relationships for a class of PfSUB1 inhibitors related to our identified hit.
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Bagnaresi P, Barros NM, Assis DM, Melo PM, Fonseca RG, Juliano MA, Pesquero JB, Juliano L, Rosenthal PJ, Carmona AK, Gazarini ML. Intracellular proteolysis of kininogen by malaria parasites promotes release of active kinins. Malar J 2012; 11:156. [PMID: 22564457 PMCID: PMC3407703 DOI: 10.1186/1475-2875-11-156] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/07/2012] [Indexed: 01/22/2023] Open
Abstract
Background The malaria burden remains a major public health concern, especially in sub-Saharan Africa. The complex biology of Plasmodium, the apicomplexan parasite responsible for this disease, challenges efforts to develop new strategies to control the disease. Proteolysis is a fundamental process in the metabolism of malaria parasites, but roles for proteases in generating vasoactive peptides have not previously been explored. Results In the present work, it was demonstrated by mass spectrometry analysis that Plasmodium parasites (Plasmodium chabaudi and Plasmodium falciparum) internalize and process plasma kininogen, thereby releasing vasoactive kinins (Lys-BK, BK and des-Arg9-BK) that may mediate haemodynamic alterations during acute malaria. In addition, it was demonstrated that the P. falciparum cysteine proteases falcipain-2 and falcipain-3 generated kinins after incubation with human kininogen, suggesting that these enzymes have an important role in this process. The biologic activity of peptides released by Plasmodium parasites was observed by measuring ileum contraction and activation of kinin receptors (B1 and B2) in HUVEC cells; the peptides elicited an increase in intracellular calcium, measured by Fluo-3 AM fluorescence. This effect was suppressed by the specific receptor antagonists Des-Arg9[Leu8]-BK and HOE-140. Conclusions In previously undescribed means of modulating host physiology, it was demonstrated that malaria parasites can generate active kinins by proteolysis of plasma kininogen.
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Affiliation(s)
- Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, Rua Pedro de Toledo, 669 - 7 andar, 04039-032, São Paulo, Brazil
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Li J, Han Q, Gong P, Yang T, Ren B, Li S, Zhang X. Toxoplasma gondii rhomboid protein 1 (TgROM1) is a potential vaccine candidate against toxoplasmosis. Vet Parasitol 2012; 184:154-60. [DOI: 10.1016/j.vetpar.2011.08.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/04/2011] [Accepted: 08/09/2011] [Indexed: 11/28/2022]
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Abstract
The blood-brain barrier (BBB) is a structural and functional barrier that protects the central nervous system (CNS) from invasion by blood-borne pathogens including parasites. However, some intracellular and extracellular parasites can traverse the BBB during the course of infection and cause neurological disturbances and/or damage which are at times fatal. The means by which parasites cross the BBB and how the immune system controls the parasites within the brain are still unclear. In this review we present the current understanding of the processes utilized by two human neuropathogenic parasites, Trypanosoma brucei spp and Toxoplasma gondii, to go across the BBB and consequences of CNS invasion. We also describe briefly other parasites that can invade the brain and how they interact with or circumvent the BBB. The roles played by parasite-derived and host-derived molecules during parasitic and white blood cell invasion of the brain are discussed.
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Affiliation(s)
- Willias Masocha
- Department of Applied Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait City, Kuwait
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Graewe S, Stanway RR, Rennenberg A, Heussler VT. Chronicle of a death foretold:Plasmodiumliver stage parasites decide on the fate of the host cell. FEMS Microbiol Rev 2012; 36:111-30. [DOI: 10.1111/j.1574-6976.2011.00297.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 06/22/2011] [Indexed: 11/27/2022] Open
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Li J, Zheng J, Gong P, Zhang X. Efficacy of Eimeria tenella rhomboid-like protein as a subunit vaccine in protective immunity against homologous challenge. Parasitol Res 2011; 110:1139-45. [DOI: 10.1007/s00436-011-2603-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 08/04/2011] [Indexed: 11/25/2022]
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Deu E, Leyva MJ, Albrow VE, Rice MJ, Ellman JA, Bogyo M. Functional studies of Plasmodium falciparum dipeptidyl aminopeptidase I using small molecule inhibitors and active site probes. ACTA ACUST UNITED AC 2011; 17:808-19. [PMID: 20797610 DOI: 10.1016/j.chembiol.2010.06.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 06/20/2010] [Accepted: 06/25/2010] [Indexed: 11/26/2022]
Abstract
The widespread resistance of malaria parasites to all affordable drugs has made the identification of new targets urgent. Dipeptidyl aminopeptidases (DPAPs) represent potentially valuable new targets that are involved in hemoglobin degradation (DPAP1) and parasite egress (DPAP3). Here we use activity-based probes to demonstrate that specific inhibition of DPAP1 by a small molecule results in the formation of an immature trophozoite that leads to parasite death. Using computational methods, we designed stable, nonpeptidic covalent inhibitors that kill Plasmodium falciparum at low nanomolar concentrations. These compounds show signs of slowing parasite growth in a murine model of malaria, which suggests that DPAP1 might be a viable antimalarial target. Interestingly, we found that resynthesis and activation of DPAP1 after inhibition is rapid, suggesting that effective drugs would need to sustain DPAP1 inhibition for a period of 2-3 hr.
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Affiliation(s)
- Edgar Deu
- Department of Pathology, Stanford School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA
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Isolation of viable Plasmodium falciparum merozoites to define erythrocyte invasion events and advance vaccine and drug development. Proc Natl Acad Sci U S A 2010; 107:14378-83. [PMID: 20660744 DOI: 10.1073/pnas.1009198107] [Citation(s) in RCA: 225] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
During blood-stage infection by Plasmodium falciparum, merozoites invade RBCs. Currently there is limited knowledge of cellular and molecular invasion events, and no established assays are available to readily measure and quantify invasion-inhibitory antibodies or compounds for vaccine and drug studies. We report the isolation of viable merozoites that retain their invasive capacity, at high purity and yield, purified by filtration of highly synchronous populations of schizonts. We show that the half-life of merozoite invasive capacity after rupture is 5 min at 37 degrees C, and 15 min at room temperature. Studying the kinetics of invasion revealed that 80% of invasion events occur within 10 min of mixing merozoites and RBCs. Invasion efficiency was maximum at low merozoite-to-RBC ratios and occurred efficiently in the absence of serum and with high concentrations of dialyzed nonimmune serum. We developed and optimized an invasion assay by using purified merozoites that enabled invasion-inhibitory activity of antibodies and compounds to be measured separately from other mechanisms of growth inhibition; the assay was more sensitive for detecting inhibitory activity than established growth-inhibition assays. Furthermore, with the use of purified merozoites it was possible to capture and fix merozoites at different stages of invasion for visualization by immunofluorescence microscopy and EM. We thereby demonstrate that processing of the major merozoite antigen merozoite surface protein-1 occurs at the time of RBC invasion. These findings have important implications for defining invasion events and molecular interactions, understanding immune interactions, and identifying and evaluating inhibitors to advance vaccine and drug development.
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Münter S, Sabass B, Selhuber-Unkel C, Kudryashev M, Hegge S, Engel U, Spatz JP, Matuschewski K, Schwarz US, Frischknecht F. Plasmodium Sporozoite Motility Is Modulated by the Turnover of Discrete Adhesion Sites. Cell Host Microbe 2009; 6:551-62. [DOI: 10.1016/j.chom.2009.11.007] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 10/21/2009] [Accepted: 11/19/2009] [Indexed: 01/19/2023]
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Abstract
SUMMARYThe invasive blood stage of malaria parasites, merozoites, are complex entities specialized for the capture and entry of red blood cells. Their potential for vaccination and other anti-malaria strategies have attracted much research attention over the last 40 years, and there is now a considerable body of data relating to their biology. In this article some of the major advances over this period and remaining challenges are reviewed.
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Erez E, Fass D, Bibi E. How intramembrane proteases bury hydrolytic reactions in the membrane. Nature 2009; 459:371-8. [PMID: 19458713 DOI: 10.1038/nature08146] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Intramembrane proteolysis is increasingly seen as a regulatory step in a range of diverse processes, including development, organelle shaping, metabolism, pathogenicity and degenerative disease. Initial scepticism over the existence of intramembrane proteases was soon replaced by intense exploration of their catalytic mechanisms, substrate specificities, regulation and structures. Crystal structures of metal-dependent and serine intramembrane proteases have revealed active sites embedded in the plane of the membrane but accessible by water, a requirement for hydrolytic reactions. Efforts to understand how these membrane-bound proteases carry out their reactions have started to yield results.
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Affiliation(s)
- Elinor Erez
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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Maier AG, Cooke BM, Cowman AF, Tilley L. Malaria parasite proteins that remodel the host erythrocyte. Nat Rev Microbiol 2009; 7:341-54. [PMID: 19369950 DOI: 10.1038/nrmicro2110] [Citation(s) in RCA: 289] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exported proteins of the malaria parasite Plasmodium falciparum interact with proteins of the erythrocyte membrane and induce substantial changes in the morphology, physiology and function of the host cell. These changes underlie the pathology that is responsible for the deaths of 1-2 million children every year due to malaria infections. The advent of molecular transfection technology, including the ability to generate deletion mutants and to introduce fluorescent reporter proteins that track the locations and dynamics of parasite proteins, has increased our understanding of the processes and machinery for export of proteins in P. falciparum-infected erythrocytes and has provided us with insights into the functions of the parasite protein exportome. We review these developments, focusing on parasite proteins that interact with the erythrocyte membrane skeleton or that promote delivery of the major virulence protein, PfEMP1, to the erythrocyte membrane.
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Affiliation(s)
- Alexander G Maier
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Melbourne, Victoria, Australia
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Freeman M. Rhomboids: 7 years of a new protease family. Semin Cell Dev Biol 2009; 20:231-9. [PMID: 19022390 DOI: 10.1016/j.semcdb.2008.10.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 10/13/2008] [Indexed: 12/24/2022]
Abstract
Drosophila Rhomboid-1 was discovered to be the first known intramembrane serine protease about 7 years ago. The study of the rhomboid-like family has since blossomed, and the purpose of this review is to take stock of where the field is, and how it may progress in the next few years. Three major themes are the increasing understanding of the biological roles of rhomboids, the detailed information we now have about their function and mechanism, and the promising leads they offer as medical targets.
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Affiliation(s)
- Matthew Freeman
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
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