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Platon L, Ménard D. Plasmodium falciparum ring-stage plasticity and drug resistance. Trends Parasitol 2024; 40:118-130. [PMID: 38104024 DOI: 10.1016/j.pt.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
Malaria is a life-threatening tropical disease caused by parasites of the genus Plasmodium, of which Plasmodium falciparum is the most lethal. Malaria parasites have a complex life cycle, with stages occurring in both the Anopheles mosquito vector and human host. Ring stages are the youngest form of the parasite in the intraerythrocytic developmental cycle and are associated with evasion of spleen clearance, temporary growth arrest (TGA), and drug resistance. This formidable ability to survive and develop into mature, sexual, or growth-arrested forms demonstrates the inherent population heterogeneity. Here we highlight the role of the ring stage as a crossroads in parasite development and as a reservoir of surviving cells in the human host via TGA survival mechanisms.
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Affiliation(s)
- Lucien Platon
- Institut Pasteur, Université Paris Cité, Malaria Genetics and Resistance Unit, INSERM U1201, F-75015 Paris, France; Sorbonne Université, Collège Doctoral ED 515 Complexité du Vivant, F-75015 Paris, France; Université de Strasbourg, Institute of Parasitology and Tropical Diseases, UR7292 Dynamics of Host-Pathogen Interactions, F-67000 Strasbourg, France.
| | - Didier Ménard
- Institut Pasteur, Université Paris Cité, Malaria Genetics and Resistance Unit, INSERM U1201, F-75015 Paris, France; Institut Pasteur, Université Paris Cité, Malaria Parasite Biology and Vaccines Unit, F-75015 Paris, France; Université de Strasbourg, Institute of Parasitology and Tropical Diseases, UR7292 Dynamics of Host-Pathogen Interactions, F-67000 Strasbourg, France; CHU Strasbourg, Laboratory of Parasitology and Medical Mycology, F-67000 Strasbourg, France.
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2
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Parres-Mercader M, Pance A, Gómez-Díaz E. Novel systems to study vector-pathogen interactions in malaria. Front Cell Infect Microbiol 2023; 13:1146030. [PMID: 37305421 PMCID: PMC10253182 DOI: 10.3389/fcimb.2023.1146030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 04/04/2023] [Indexed: 06/13/2023] Open
Abstract
Some parasitic diseases, such as malaria, require two hosts to complete their lifecycle: a human and an insect vector. Although most malaria research has focused on parasite development in the human host, the life cycle within the vector is critical for the propagation of the disease. The mosquito stage of the Plasmodium lifecycle represents a major demographic bottleneck, crucial for transmission blocking strategies. Furthermore, it is in the vector, where sexual recombination occurs generating "de novo" genetic diversity, which can favor the spread of drug resistance and hinder effective vaccine development. However, understanding of vector-parasite interactions is hampered by the lack of experimental systems that mimic the natural environment while allowing to control and standardize the complexity of the interactions. The breakthrough in stem cell technologies has provided new insights into human-pathogen interactions, but these advances have not been translated into insect models. Here, we review in vivo and in vitro systems that have been used so far to study malaria in the mosquito. We also highlight the relevance of single-cell technologies to progress understanding of these interactions with higher resolution and depth. Finally, we emphasize the necessity to develop robust and accessible ex vivo systems (tissues and organs) to enable investigation of the molecular mechanisms of parasite-vector interactions providing new targets for malaria control.
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Affiliation(s)
- Marina Parres-Mercader
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas (IPBLN, CSIC), Granada, Spain
| | - Alena Pance
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, United Kingdom
| | - Elena Gómez-Díaz
- Instituto de Parasitología y Biomedicina López-Neyra, Consejo Superior de Investigaciones Científicas (IPBLN, CSIC), Granada, Spain
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3
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Jia X, Liu F, Bai J, Zhang Y, Cui L, Cao Y, Luo E. Phosphatase inhibitors BVT-948 and alexidine dihydrochloride inhibit sexual development of the malaria parasite Plasmodium berghei. Int J Parasitol Drugs Drug Resist 2022; 19:81-88. [PMID: 35792443 PMCID: PMC9260261 DOI: 10.1016/j.ijpddr.2022.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/18/2022] [Accepted: 06/22/2022] [Indexed: 11/20/2022]
Abstract
Background With the emergence of resistance to front-line antimalarials, there is an urgent need to develop new medicines, including those targeting sexual development. This study aimed to assess the activity of a panel of phosphatase inhibitors against the sexual development of Plasmodium berghei and evaluate their potential as transmission-blocking agents. Methods Twenty-five compounds were screened for transmission-blocking activity in vitro using the P. berghei ookinete culture assay. The inhibitory effects on male gametogenesis, gamete-ookinete, and zygote-ookinete formation were evaluated. The transmission-blocking activity of two compounds was evaluated using an in vivo mosquito feeding assay. Their cytotoxic effects were assessed on the human cell line HepG2. Results Twelve compounds inhibited P. berghei ookinete formation with an IC50 < 10 μM. Two compounds, BVT-948 and alexidine dihydrochloride, significantly inhibited different developmental stages from gametogenesis through ookinete maturation. They also showed a substantial in vivo transmission-blocking activity by the mosquito feeding assay. Conclusions Some phosphatase inhibitors effectively inhibited Plasmodium sexual development and exhibited evident transmission-blocking activity, suggesting that phosphatases are valid targets for antimalarial development. BVT-948 and alexidine·2HCl inhibit sexual developmental stages of Plasmodium. BVT-948 and alexidine·2HCl show a substantial transmission-blocking activity. BVT-948 and alexidine·2HCl show a relatively low cytotoxicity to HepG2 cells. Phosphatases are valid targets for antimalarial development.
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Affiliation(s)
- Xitong Jia
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Fei Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Jie Bai
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Yongzhe Zhang
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China; Department of Nephrology, Shengjing Hospital of China Medical University, Shenyang, Liaoning, 110004, China
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL, 33612-9415, USA
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China.
| | - Enjie Luo
- Department of Pathogen Biology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China.
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A Histone Deacetylase (HDAC) Inhibitor with Pleiotropic In Vitro Anti- Toxoplasma and Anti- Plasmodium Activities Controls Acute and Chronic Toxoplasma Infection in Mice. Int J Mol Sci 2022; 23:ijms23063254. [PMID: 35328672 PMCID: PMC8952293 DOI: 10.3390/ijms23063254] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/21/2022] Open
Abstract
Toxoplasmosis is a highly prevalent human disease, and virulent strains of this parasite emerge from wild biotopes. Here, we report on the potential of a histone deacetylase (HDAC) inhibitor we previously synthesized, named JF363, to act in vitro against a large panel of Toxoplasma strains, as well as against the liver and blood stages of Plasmodium parasites, the causative agents of malaria. In vivo administration of the drug significantly increases the survival of mice during the acute phase of infection by T. gondii, thus delaying its spreading. We further provide evidence of the compound’s efficiency in controlling the formation of cysts in the brain of T. gondii-infected mice. A convincing docking of the JF363 compound in the active site of the five annotated ME49 T. gondii HDACs was performed by extensive sequence–structure comparison modeling. The resulting complexes show a similar mode of binding in the five paralogous structures and a quite similar prediction of affinities in the micromolar range. Altogether, these results pave the way for further development of this compound to treat acute and chronic toxoplasmosis. It also shows promise for the future development of anti-Plasmodium therapeutic interventions.
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Yu S, Wang J, Luo X, Zheng H, Wang L, Yang X, Wang Y. Transmission-Blocking Strategies Against Malaria Parasites During Their Mosquito Stages. Front Cell Infect Microbiol 2022; 12:820650. [PMID: 35252033 PMCID: PMC8889032 DOI: 10.3389/fcimb.2022.820650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 01/31/2022] [Indexed: 11/24/2022] Open
Abstract
Malaria is still the most widespread parasitic disease and causes the most infections globally. Owing to improvements in sanitary conditions and various intervention measures, including the use of antimalarial drugs, the malaria epidemic in many regions of the world has improved significantly in the past 10 years. However, people living in certain underdeveloped areas are still under threat. Even in some well-controlled areas, the decline in malaria infection rates has stagnated or the rates have rebounded because of the emergence and spread of drug-resistant malaria parasites. Thus, new malaria control methods must be developed. As the spread of the Plasmodium parasite is dependent on the part of its life cycle that occurs in mosquitoes, to eliminate the possibility of malaria infections, transmission-blocking strategies against the mosquito stage should be the first choice. In fact, after the gametocyte enters the mosquito body, it undergoes a series of transformation processes over a short period, thus providing numerous potential blocking targets. Many research groups have carried out studies based on targeting the blocking of transmission during the mosquito phase and have achieved excellent results. Meanwhile, the direct killing of mosquitoes could also significantly reduce the probability of malaria infections. Microorganisms that display complex interactions with Plasmodium, such as Wolbachia and gut flora, have shown observable transmission-blocking potential. These could be used as a biological control strategy and play an important part in blocking the transmission of malaria.
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Affiliation(s)
- Shasha Yu
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
| | - Jing Wang
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
| | - Xue Luo
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
| | - Hong Zheng
- Department of Thoracic Surgery, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Luhan Wang
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
| | - Xuesen Yang
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
| | - Ying Wang
- Department of Tropical Medicine, College of Military Preventive Medicine, Army Medical University, Chongqing, China
- *Correspondence: Ying Wang,
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Synthesis and antiplasmodial activity of regioisomers and epimers of second-generation dual acting ivermectin hybrids. Sci Rep 2022; 12:564. [PMID: 35022455 PMCID: PMC8755717 DOI: 10.1038/s41598-021-04532-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/23/2021] [Indexed: 12/15/2022] Open
Abstract
With its strong effect on vector-borne diseases, and insecticidal effect on mosquito vectors of malaria, inhibition of sporogonic and blood-stage development of Plasmodium falciparum, as well as in vitro and in vivo impairment of the P. berghei development inside hepatocytes, ivermectin (IVM) continues to represent an antimalarial therapeutic worthy of investigation. The in vitro activity of the first-generation IVM hybrids synthesized by appending the IVM macrolide with heterocyclic and organometallic antimalarial pharmacophores, against the blood-stage and liver-stage infections by Plasmodium parasites prompted us to design second-generation molecular hybrids of IVM. Here, a structural modification of IVM to produce novel molecular hybrids by using sub-structures of 4- and 8-aminoquinolines, the time-tested antiplasmodial agents used for treating the blood and hepatic stage of Plasmodium infections, respectively, is presented. Successful isolation of regioisomers and epimers has been demonstrated, and the evaluation of their in vitro antiplasmodial activity against both the blood stages of P. falciparum and the hepatic stages of P. berghei have been undertaken. These compounds displayed structure-dependent antiplasmodial activity, in the nM range, which was more potent than that of IVM, its aglycon or primaquine, highlighting the superiority of this hybridization strategy in designing new antiplasmodial agents.
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Bailly C. The bacterial thiopeptide thiostrepton. An update of its mode of action, pharmacological properties and applications. Eur J Pharmacol 2022; 914:174661. [PMID: 34863996 DOI: 10.1016/j.ejphar.2021.174661] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/29/2021] [Indexed: 12/20/2022]
Abstract
The bacterial thiopeptide thiostrepton (TS) is used as a veterinary medicine to treat bacterial infections. TS is a protein translation inhibitor, essentially active against Gram-positive bacteria and some Gram-negative bacteria. In procaryotes, TS abrogates binding of GTPase elongation factors to the 70S ribosome, by altering the structure of rRNA-L11 protein complexes. TS exerts also antimalarial effects by disrupting protein synthesis in the apicoplast genome of Plasmodium falciparum. Interestingly, the drug targets both the infectious pathogen (bacteria or parasite) and host cell, by inducing endoplasmic reticulum stress-mediated autophagy which contributes to enhance the host cell defense. In addition, TS has been characterized as a potent chemical inhibitor of the oncogenic transcription factor FoxM1, frequently overexpressed in cancers or other diseases. The capacity of TS to crosslink FoxM1, and a few other proteins such as peroxiredoxin 3 (PRX3) and the 19S proteasome, contributes to the anticancer effects of the thiopeptide. The anticancer activities of TS evidenced using diverse tumor cell lines, in vivo models and drug combinations are reviewed here, together with the implicated targets and mechanisms. The difficulty to formulate TS is a drag on the pharmaceutical development of the natural product. However, the design of hemisynthetic analogues and the use of micellar drug delivery systems should facilitate a broader utilization of the compound in human and veterinary medicines. This review shed light on the many pharmacological properties of TS, with the objective to promote its use as a pharmacological tool and medicinal product.
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Affiliation(s)
- Christian Bailly
- OncoWitan, Scientific Consulting Office, Lille, Wasquehal, 59290, France.
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A New Thienopyrimidinone Chemotype Shows Multistage Activity against Plasmodium falciparum, Including Artemisinin-Resistant Parasites. Microbiol Spectr 2021; 9:e0027421. [PMID: 34724729 PMCID: PMC8557901 DOI: 10.1128/spectrum.00274-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human malaria infection begins with a one-time asymptomatic liver stage followed by a cyclic symptomatic blood stage. For decades, the research for novel antimalarials focused on the high-throughput screening of molecules that only targeted the asexual blood stages. In a search for new effective compounds presenting a triple action against erythrocytic and liver stages in addition to the ability to block the transmission of the disease via the mosquito vector, 2-amino-thienopyrimidinone derivatives were synthesized and tested for their antimalarial activity. One molecule, named gamhepathiopine (denoted as “M1” herein), was active at submicromolar concentrations against both erythrocytic (50% effective concentration [EC50] = 0.045 μM) and liver (EC50 = 0.45 μM) forms of Plasmodium falciparum. Furthermore, gamhepathiopine efficiently blocked the development of the sporogonic cycle in the mosquito vector by inhibiting the exflagellation step. Moreover, M1 was active against artemisinin-resistant forms (EC50 = 0.227 μM), especially at the quiescent stage. Nevertheless, in mice, M1 showed modest activity due to its rapid metabolization by P450 cytochromes into inactive derivatives, calling for the development of new parent compounds with improved metabolic stability and longer half-lives. These results highlight the thienopyrimidinone scaffold as a novel antiplasmodial chemotype of great interest to search for new drug candidates displaying multistage activity and an original mechanism of action with the potential to be used in combination therapies for malaria elimination in the context of artemisinin resistance. IMPORTANCE This work reports a new chemical structure that (i) displays activity against the human malaria parasite Plasmodium falciparum at 3 stages of the parasitic cycle (blood stage, hepatic stage, and sexual stages), (ii) remains active against parasites that are resistant to the first-line treatment recommended by the World Health Organization (WHO) for the treatment of severe malaria (artemisinins), and (iii) reduces transmission of the parasite to the mosquito vector in a mouse model. This new molecule family could open the way to the conception of novel antimalarial drugs with an original multistage mechanism of action to fight against Plasmodium drug resistance and block interhuman transmission of malaria.
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Villa M, Buysse M, Berthomieu A, Rivero A. The transmission-blocking effects of antimalarial drugs revisited: fitness costs and sporontocidal effects of artesunate and sulfadoxine-pyrimethamine. Int J Parasitol 2021; 51:279-289. [PMID: 33508331 DOI: 10.1016/j.ijpara.2020.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 12/31/2022]
Abstract
Assays used to evaluate the transmission-blocking activity of antimalarial drugs are largely focused on their potential to inhibit or reduce the infectivity of gametocytes, the blood stages of the parasite that are responsible for the onward transmission to the mosquito vector. For this purpose, the drug is administered concomitantly with gametocyte-infected blood, and the results are evaluated as the percentage of reduction in the number of oocysts in the mosquito midgut. We report the results of a series of experiments that explore the transmission-blocking potential of two key antimalarial drugs, artesunate and sulfadoxine-pyrimethamine, when administered to mosquitoes already infected from a previous blood meal. For this purpose, uninfected mosquitoes and mosquitoes carrying a 6 day old Plasmodium relictum infection (early oocyst stages) were allowed to feed either on a drug-treated or an untreated host in a fully factorial experiment. This protocol allowed us to bypass the gametocyte stages and establish whether the drugs have a sporontocidal effect, i.e. whether they are able to arrest the ongoing development of oocysts and sporozoites, as would be the case when a mosquito takes a post-infection treated blood meal. In a separate experiment, we also explored whether a drug-treated blood meal impacted key life history traits of the mosquito relevant for transmission, and if this depended on their infection status. Our results showed that feeding on an artesunate- or sulfadoxine-pyrimethamine-treated hosts has no epidemiologically relevant effects on the fitness of infected or uninfected mosquitoes. In contrast, when infected mosquitoes fed on an sulfadoxine-pyrimethamine-treated host, we observed both a significant increase in the number of oocysts in the midgut, and a drastic decrease in both sporozoite prevalence (-30%) and burden (-80%) compared with the untreated controls. We discuss the potential mechanisms underlying these seemingly contradictory results and contend that, provided the results are translatable to human malaria, the potential epidemiological and evolutionary consequences of the current preventive use of sulfadoxine-pyrimethamine in malaria-endemic countries could be substantial.
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Affiliation(s)
- M Villa
- MIVEGEC (CNRS - IRD - Université de Montpellier), France.
| | - M Buysse
- MIVEGEC (CNRS - IRD - Université de Montpellier), France
| | - A Berthomieu
- MIVEGEC (CNRS - IRD - Université de Montpellier), France; CREES (Centre d'Écologie et Évolution de la Santé, Montpellier), 911 avenue Agropolis, 34394 Montpellier, France
| | - A Rivero
- MIVEGEC (CNRS - IRD - Université de Montpellier), France; CREES (Centre d'Écologie et Évolution de la Santé, Montpellier), 911 avenue Agropolis, 34394 Montpellier, France
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Recio-Tótoro B, Condé R, Claudio-Piedras F, Lanz-Mendoza H. Affinity purification of Plasmodium ookinetes from in vitro cultures using extracellular matrix gel. Parasitol Int 2020; 80:102242. [PMID: 33152548 DOI: 10.1016/j.parint.2020.102242] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 10/19/2020] [Accepted: 10/31/2020] [Indexed: 12/26/2022]
Abstract
Malaria transmission depends on the parasites' successful invasion of the mosquito. This is achieved by the ookinete, a motile zygote that forms in the blood bolus after the mosquito takes an infectious blood meal. The ookinete invades the midgut epithelium and strongly attaches to the basal lamina, differentiating into an oocyst that produces the vertebrate-invasive sporozoites. Despite their importance, the ookinete and the oocyst are the least studied stages of the parasite. Much of what we know about the ookinete comes from in vitro experiments, which are hindered by the concomitant contamination with blood cells and other parasite stages. Although methods to purify them exist, they vary in terms of yield, costs, and difficulty to perform. A method for ookinete purification taking advantage of their adhesive properties was herein developed. The method consists of covering any culture-suitable surface with extracellular matrix gel, after which the ookinete culture is incubated on the gel to allow for ookinete attachment. The contaminant cells are then simply washed away. This procedure results in purer and less stressed ookinete preparations, which, by the nature of the method, are ready for oocyst production. Furthermore, it allows for micro-purifications using only 1 μl of blood, opening the possibility to make axenic ookinete cultures without sacrificing mice.
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Affiliation(s)
- Benito Recio-Tótoro
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, 62100 Cuernavaca, Morelos, Mexico; Instituto de Biotecnología, Universidad Nacional Autónoma de México, 62210 Cuernavaca, Morelos, Mexico
| | - Renaud Condé
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, 62100 Cuernavaca, Morelos, Mexico
| | - Fabiola Claudio-Piedras
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, 62100 Cuernavaca, Morelos, Mexico
| | - Humberto Lanz-Mendoza
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, 62100 Cuernavaca, Morelos, Mexico.
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Moyo P, Mugumbate G, Eloff JN, Louw AI, Maharaj VJ, Birkholtz LM. Natural Products: A Potential Source of Malaria Transmission Blocking Drugs? Pharmaceuticals (Basel) 2020; 13:E251. [PMID: 32957668 PMCID: PMC7558993 DOI: 10.3390/ph13090251] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/17/2022] Open
Abstract
The ability to block human-to-mosquito and mosquito-to-human transmission of Plasmodium parasites is fundamental to accomplish the ambitious goal of malaria elimination. The WHO currently recommends only primaquine as a transmission-blocking drug but its use is severely restricted by toxicity in some populations. New, safe and clinically effective transmission-blocking drugs therefore need to be discovered. While natural products have been extensively investigated for the development of chemotherapeutic antimalarial agents, their potential use as transmission-blocking drugs is comparatively poorly explored. Here, we provide a comprehensive summary of the activities of natural products (and their derivatives) of plant and microbial origins against sexual stages of Plasmodium parasites and the Anopheles mosquito vector. We identify the prevailing challenges and opportunities and suggest how these can be mitigated and/or exploited in an endeavor to expedite transmission-blocking drug discovery efforts from natural products.
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Affiliation(s)
- Phanankosi Moyo
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Grace Mugumbate
- Department of Chemistry, School of Natural Sciences and Mathematics, Chinhoyi University of Technology, Private Bag, 7724 Chinhoyi, Zimbabwe;
| | - Jacobus N. Eloff
- Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag x04, Onderstepoort 0110 Pretoria, South Africa;
| | - Abraham I. Louw
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Vinesh J. Maharaj
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Lyn-Marié Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
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Abstract
As the world gets closer to eliminating malaria, the scientific community worldwide has begun to realize the importance of malaria transmission-blocking interventions. The onus of breaking the life cycle of the human malaria parasite Plasmodium falciparum predominantly rests upon transmission-blocking drugs because of emerging resistance to commonly used schizonticides and insecticides. This third part of our review series on malaria transmission-blocking entails transmission-blocking potential of preclinical transmission-blocking antimalarials and other non-malaria drugs/experimental compounds that are not in clinical or preclinical development for malaria but possess transmission-blocking potential. Collective analysis of the structure and the activity of these experimental compounds might pave the way toward generation of novel prototypes of next-generation transmission-blocking drugs.
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13
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Siden-Kiamos I, Spanos L, Currà C. A method for purification of Plasmodium oocysts from mosquito midguts. Sci Rep 2020; 10:7262. [PMID: 32350329 PMCID: PMC7190746 DOI: 10.1038/s41598-020-64121-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 04/09/2020] [Indexed: 11/09/2022] Open
Abstract
Malaria parasites have a complex life cycle comprising development in two hosts, the vertebrate and the vector mosquito. In the gut of the mosquito, the parasite develops into the oocyst, which is settled beneath the epithelium and attached to the basal lamina of the gut until the maturation of the cyst and its rupture concomitant with the release of the sporozoites, the infectious form of the parasite. The oocyst represents the longest stage of the parasite life cycle but it is poorly understood, mainly because of the difficulties to separate the oocysts from the mosquito midgut tissue but also the lack of a robust method to reproduce this stage in vitro. Here we describe a simple and reproducible protocol for purification of oocysts from mosquitoes. Midguts were dissected from infected mosquitoes and treated with trypsin which resulted in the degradation of the basal lamina and the release of the oocysts from the midgut tissue. The results obtained showed that the isolated oocysts were free of the mosquito protein E-cadherin. Purified oocysts were alive as judged by a strong GFP signal at least up to 2 h after treatment and furthermore sporozoites that had developed in the cyst were able to glide. Our new method will allow the study of the oocyst composition, formation and development in more details leading to advances in knowledge of this Plasmodium stage.
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Affiliation(s)
- Inga Siden-Kiamos
- Institute of molecular biology and biotechnology, Foundation for research and technology - Hellas, Heraklion, Greece
| | - Lefteris Spanos
- Institute of molecular biology and biotechnology, Foundation for research and technology - Hellas, Heraklion, Greece
| | - Chiara Currà
- Institute of molecular biology and biotechnology, Foundation for research and technology - Hellas, Heraklion, Greece.
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Azevedo R, Mendes AM, Prudêncio M. The Impact of Antiretroviral Therapy on Malaria Parasite Transmission. Front Microbiol 2020; 10:3048. [PMID: 32038528 PMCID: PMC6993566 DOI: 10.3389/fmicb.2019.03048] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/18/2019] [Indexed: 12/11/2022] Open
Abstract
Coendemicity between the human immunodeficiency virus (HIV) and Plasmodium parasites, the causative agents of acquired immunodeficiency syndrome (AIDS) and malaria, respectively, occurs in several regions around the world. Although the impact of the interaction between these two organisms is not well understood, it is thought that the outcome of either disease may be negatively influenced by coinfection. Therefore, it is important to understand how current first-line antiretroviral therapies (ART) might impact Plasmodium infection in these regions. Here, we describe the effect of 18 antiretroviral compounds and of first-line ART on the blood and sporogonic stages of Plasmodium berghei in vitro and in vivo. We show that the combination zidovudine + lamivudine + lopinavir/ritonavir (LPV/r), employed as first-line HIV treatment in the field, has a strong inhibitory activity on the sporogonic stages of P. berghei and that several non-nucleoside reverse transcriptase inhibitors (NNRTI) have a moderate effect on this stage of the parasite’s life cycle. Our results expose the effect of current first-line ART on Plasmodium infection and identify potential alternative therapies for HIV/AIDS that might impact malaria transmission.
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Affiliation(s)
- Raquel Azevedo
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - António M Mendes
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
| | - Miguel Prudêncio
- Faculdade de Medicina, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal
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15
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Abstract
The scientific community worldwide has realized that malaria elimination will not be possible without development of safe and effective transmission-blocking interventions. Primaquine, the only WHO recommended transmission-blocking drug, is not extensively utilized because of the toxicity issues in G6PD deficient individuals. Therefore, there is an urgent need to develop novel therapeutic interventions that can target malaria parasites and effectively block transmission. But at first, it is imperative to unravel the existing portfolio of transmission-blocking drugs. This review highlights transmission-blocking potential of current antimalarial drugs and drugs that are in various stages of clinical development. The collective analysis of the relationships between the structure and the activity of transmission-blocking drugs is expected to help in the design of new transmission-blocking antimalarials.
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16
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Azevedo R, Mendes AM, Prudêncio M. Inhibition of Plasmodium sporogonic stages by ivermectin and other avermectins. Parasit Vectors 2019; 12:549. [PMID: 31752986 PMCID: PMC6873674 DOI: 10.1186/s13071-019-3805-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 11/12/2019] [Indexed: 12/15/2022] Open
Abstract
Background The transmissible forms of Plasmodium parasites result from a process of sporogony that takes place inside their obligatory mosquito vector and culminates in the formation of mammalian-infective parasite forms. Ivermectin is a member of the avermectin family of endectocides, which has been proposed to inhibit malaria transmission due its insecticidal effect. However, it remains unclear whether ivermectin also exerts a direct action on the parasite’s blood and transmission stages. Methods We employed a rodent model of infection to assess the impact of ivermectin treatment on P. berghei asexual and sexual blood forms in vivo. We then made use of a newly established luminescence-based methodology to evaluate the activity of ivermectin and other avermectins against the sporogonic stages of P. berghei parasites in vitro independent of their role on mosquito physiology. Results Our results show that whereas ivermectin does not affect the parasite’s parasitemia, gametocytemia or exflagellation in the mammalian host, several members of the avermectin family of compounds exert a strong inhibitory effect on the generation and development of P. berghei oocysts. Conclusions Our results shed light on the action of avermectins against Plasmodium transmission stages and highlight the potential of these compounds to help prevent the spread of malaria.
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Affiliation(s)
- Raquel Azevedo
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal
| | - António M Mendes
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
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17
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Spreng B, Fleckenstein H, Kübler P, Di Biagio C, Benz M, Patra P, Schwarz US, Cyrklaff M, Frischknecht F. Microtubule number and length determine cellular shape and function in Plasmodium. EMBO J 2019; 38:e100984. [PMID: 31368598 PMCID: PMC6669926 DOI: 10.15252/embj.2018100984] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 04/12/2019] [Accepted: 04/26/2019] [Indexed: 11/27/2022] Open
Abstract
Microtubules are cytoskeletal filaments essential for many cellular processes, including establishment and maintenance of polarity, intracellular transport, division and migration. In most metazoan cells, the number and length of microtubules are highly variable, while they can be precisely defined in some protozoan organisms. However, in either case the significance of these two key parameters for cells is not known. Here, we quantitatively studied the impact of modulating microtubule number and length in Plasmodium, the protozoan parasite causing malaria. Using a gene deletion and replacement strategy targeting one out of two α-tubulin genes, we show that chromosome segregation proceeds in the oocysts even in the absence of microtubules. However, fewer and shorter microtubules severely impaired the formation, motility and infectivity of Plasmodium sporozoites, the forms transmitted by the mosquito, which usually contain 16 microtubules. We found that α-tubulin expression levels directly determined the number of microtubules, suggesting a high nucleation barrier as supported by a mathematical model. Infectious sporozoites were only formed in parasite lines featuring at least 10 microtubules, while parasites with 9 or fewer microtubules failed to transmit.
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Affiliation(s)
- Benjamin Spreng
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Hannah Fleckenstein
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Patrick Kübler
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Claudia Di Biagio
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Madlen Benz
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Pintu Patra
- Institute for Theoretical Physics and BioquantHeidelberg UniversityHeidelbergGermany
| | - Ulrich S Schwarz
- Institute for Theoretical Physics and BioquantHeidelberg UniversityHeidelbergGermany
| | - Marek Cyrklaff
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
| | - Friedrich Frischknecht
- Integrative ParasitologyCenter for Infectious DiseasesHeidelberg University Medical SchoolHeidelbergGermany
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18
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Critical examination of approaches exploited to assess the effectiveness of transmission-blocking drugs for malaria. Future Med Chem 2018; 10:2619-2639. [PMID: 30499742 DOI: 10.4155/fmc-2018-0169] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In the absence of clinically proven vaccines and emerging resistance to common antimalarials and insecticides, the onus of interrupting the life cycle of Plasmodium falciparum, is upon the transmission-blocking drugs. Current transmission-blocking drug primaquine finds its use restricted because of associated hemolytic toxicity issues in Glucose-6-Phosphate-Dehydrogenase deficient individuals. This article provides an extensive review of the assays used by the investigators to evaluate the transmission-blocking activity of drugs. Furthermore, limitations in existing transmission-blocking assessment approaches/studies are also covered in detail. This review is expected to help in the identification of lacunae in current understanding of transmission-blocking strategies, which are hindering our efforts to develop sustainable and effective transmission-blocking interventions.
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19
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Screening the Pathogen Box for Molecules Active against Plasmodium Sexual Stages Using a New Nanoluciferase-Based Transgenic Line of P. berghei Identifies Transmission-Blocking Compounds. Antimicrob Agents Chemother 2018; 62:AAC.01053-18. [PMID: 30181368 DOI: 10.1128/aac.01053-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/28/2018] [Indexed: 12/12/2022] Open
Abstract
Malaria remains an important parasitic disease with a large morbidity and mortality burden. Plasmodium transmission-blocking (TB) compounds are essential for achieving malaria elimination efforts. Recent efforts to develop high-throughput screening (HTS) methods to identify compounds that inhibit or kill gametocytes, the Plasmodium sexual stage infectious to mosquitoes, have yielded insight into new TB compounds. However, the activities of these compounds against gametes, formed in the first minutes of mosquito infection, are typically not assessed, unless screened in a standard membrane feeding assay, a labor-intensive assay. We demonstrate here the generation of a Plasmodium model for drug screens against gametes and fertilization. The new P. berghei line, named Ookluc, was genetically and pharmacologically validated and scalable for HTS. Screening the Pathogen Box from the Medicines for Malaria Venture using the new model identified promising TB compounds. The use of Ookluc in different libraries of compounds may aid in the identification of transmission-blocking drugs not assessed in screens against asexual stages or gametocytes.
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20
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Costa G, Gildenhard M, Eldering M, Lindquist RL, Hauser AE, Sauerwein R, Goosmann C, Brinkmann V, Carrillo-Bustamante P, Levashina EA. Non-competitive resource exploitation within mosquito shapes within-host malaria infectivity and virulence. Nat Commun 2018; 9:3474. [PMID: 30150763 PMCID: PMC6110728 DOI: 10.1038/s41467-018-05893-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 08/01/2018] [Indexed: 11/22/2022] Open
Abstract
Malaria is a fatal human parasitic disease transmitted by a mosquito vector. Although the evolution of within-host malaria virulence has been the focus of many theoretical and empirical studies, the vector’s contribution to this process is not well understood. Here, we explore how within-vector resource exploitation would impact the evolution of within-host Plasmodium virulence. By combining within-vector dynamics and malaria epidemiology, we develop a mathematical model, which predicts that non-competitive parasitic resource exploitation within-vector restricts within-host parasite virulence. To validate our model, we experimentally manipulate mosquito lipid trafficking and gauge within-vector parasite development and within-host infectivity and virulence. We find that mosquito-derived lipids determine within-host parasite virulence by shaping development (quantity) and metabolic activity (quality) of transmissible sporozoites. Our findings uncover the potential impact of within-vector environment and vector control strategies on the evolution of malaria virulence. The evolution of within-host malaria virulence has been studied, but the vector’s contribution isn’t well understood. Here, Costa et al. show that non-competitive parasitic resource exploitation within-vector, in particular lipid trafficking, restricts within-host infectivity and virulence of the parasite.
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Affiliation(s)
- G Costa
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - M Gildenhard
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - M Eldering
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany.,Department of Medical Microbiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - R L Lindquist
- Immunodynamics, German Rheumatism Research Centre (DRFZ), 10117, Berlin, Germany
| | - A E Hauser
- Immunodynamics, German Rheumatism Research Centre (DRFZ), 10117, Berlin, Germany.,Immune Dynamics and Intravital Microscopy, Charité-Universitätsmedizin, 10117, Berlin, Germany
| | - R Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - C Goosmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - V Brinkmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - P Carrillo-Bustamante
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - E A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany.
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21
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Mendes AM, Machado M, Gonçalves-Rosa N, Reuling IJ, Foquet L, Marques C, Salman AM, Yang ASP, Moser KA, Dwivedi A, Hermsen CC, Jiménez-Díaz B, Viera S, Santos JM, Albuquerque I, Bhatia SN, Bial J, Angulo-Barturen I, Silva JC, Leroux-Roels G, Janse CJ, Khan SM, Mota MM, Sauerwein RW, Prudêncio M. A Plasmodium berghei sporozoite-based vaccination platform against human malaria. NPJ Vaccines 2018; 3:33. [PMID: 30155278 PMCID: PMC6109154 DOI: 10.1038/s41541-018-0068-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/21/2018] [Accepted: 05/31/2018] [Indexed: 12/15/2022] Open
Abstract
There is a pressing need for safe and highly effective Plasmodium falciparum (Pf) malaria vaccines. The circumsporozoite protein (CS), expressed on sporozoites and during early hepatic stages, is a leading target vaccine candidate, but clinical efficacy has been modest so far. Conversely, whole-sporozoite (WSp) vaccines have consistently shown high levels of sterilizing immunity and constitute a promising approach to effective immunization against malaria. Here, we describe a novel WSp malaria vaccine that employs transgenic sporozoites of rodent P. berghei (Pb) parasites as cross-species immunizing agents and as platforms for expression and delivery of PfCS (PbVac). We show that both wild-type Pb and PbVac sporozoites unabatedly infect and develop in human hepatocytes while unable to establish an infection in human red blood cells. In a rabbit model, similarly susceptible to Pb hepatic but not blood infection, we show that PbVac elicits cross-species cellular immune responses, as well as PfCS-specific antibodies that efficiently inhibit Pf sporozoite liver invasion in human hepatocytes and in mice with humanized livers. Thus, PbVac is safe and induces functional immune responses in preclinical studies, warranting clinical testing and development. A genetically engineered parasite, related to malaria-causing Plasmodium falciparum, excels as a vaccine in preclinical tests. A team led by Miguel Prudêncio, of the University of Lisbon, Portugal, developed a genetically altered vaccine candidate based on Plasmodium berghei, which is pathogenic to rodents but, in humans, fails to progress from a harmless, transient liver infection to causing full, blood-borne malaria. The candidate expresses a human form of ‘circumsporozoite protein,’ a known antigen, and is designed to provoke a more comprehensive immune response as it presents a whole pathogen to the host. In preclinical tests, the candidate generated antibodies able to neutralize infection in human hepatocytes and also provoked a cellular immune response in rabbits. The team’s candidate proved safe and efficacious, warranting further trials and clinical testing.
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Affiliation(s)
- António M Mendes
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Marta Machado
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Nataniel Gonçalves-Rosa
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Isaie J Reuling
- 2Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB Nijmegen, The Netherlands
| | - Lander Foquet
- 3Center for Vaccinology, Ghent University and Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.,Departments of Clinical Chemistry, Microbiology and Immunology, Ghent University, Ghent University Hospital, Ghent, Belgium
| | - Cláudia Marques
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Ahmed M Salman
- 5Leiden Malaria Research Group, Parasitology, Center of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands.,6The Jenner Institute, Nuffield Department of Medicine, University of Oxford, ORCRB, Roosevelt Drive, Oxford, OX3 7DQ UK
| | - Annie S P Yang
- 2Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB Nijmegen, The Netherlands
| | - Kara A Moser
- 7Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Ankit Dwivedi
- 7Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Cornelus C Hermsen
- 2Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB Nijmegen, The Netherlands
| | - Belén Jiménez-Díaz
- 8Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa, 2, 28760 Tres Cantos, Madrid Spain
| | - Sara Viera
- 8Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa, 2, 28760 Tres Cantos, Madrid Spain
| | - Jorge M Santos
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal.,12Present Address: Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Avenue, 02115 Boston, MA USA
| | - Inês Albuquerque
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Sangeeta N Bhatia
- 9Health Sciences and Technology/Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - John Bial
- 10Yecuris Corporation, PO Box 4645, Tualatin, OR 97062 USA
| | - Iñigo Angulo-Barturen
- 8Diseases of the Developing World, GlaxoSmithKline, Severo Ochoa, 2, 28760 Tres Cantos, Madrid Spain
| | - Joana C Silva
- 7Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201 USA.,11Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Geert Leroux-Roels
- 3Center for Vaccinology, Ghent University and Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Chris J Janse
- 5Leiden Malaria Research Group, Parasitology, Center of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Shahid M Khan
- 5Leiden Malaria Research Group, Parasitology, Center of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Maria M Mota
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Robert W Sauerwein
- 2Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB Nijmegen, The Netherlands
| | - Miguel Prudêncio
- 1Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisboa, Portugal
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