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Singh P, Lonardi S, Liang Q, Vydyam P, Khabirova E, Fang T, Gihaz S, Thekkiniath J, Munshi M, Abel S, Ciampossin L, Batugedara G, Gupta M, Lu XM, Lenz T, Chakravarty S, Cornillot E, Hu Y, Ma W, Gonzalez LM, Sánchez S, Estrada K, Sánchez-Flores A, Montero E, Harb OS, Le Roch KG, Mamoun CB. Babesia duncani multi-omics identifies virulence factors and drug targets. Nat Microbiol 2023; 8:845-859. [PMID: 37055610 PMCID: PMC10159843 DOI: 10.1038/s41564-023-01360-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 03/14/2023] [Indexed: 04/15/2023]
Abstract
Babesiosis is a malaria-like disease in humans and animals that is caused by Babesia species, which are tick-transmitted apicomplexan pathogens. Babesia duncani causes severe to lethal infection in humans, but despite the risk that this parasite poses as an emerging pathogen, little is known about its biology, metabolic requirements or pathogenesis. Unlike other apicomplexan parasites that infect red blood cells, B. duncani can be continuously cultured in vitro in human erythrocytes and can infect mice resulting in fulminant babesiosis and death. We report comprehensive, detailed molecular, genomic, transcriptomic and epigenetic analyses to gain insights into the biology of B. duncani. We completed the assembly, 3D structure and annotation of its nuclear genome, and analysed its transcriptomic and epigenetics profiles during its asexual life cycle stages in human erythrocytes. We used RNA-seq data to produce an atlas of parasite metabolism during its intraerythrocytic life cycle. Characterization of the B. duncani genome, epigenome and transcriptome identified classes of candidate virulence factors, antigens for diagnosis of active infection and several attractive drug targets. Furthermore, metabolic reconstitutions from genome annotation and in vitro efficacy studies identified antifolates, pyrimethamine and WR-99210 as potent inhibitors of B. duncani to establish a pipeline of small molecules that could be developed as effective therapies for the treatment of human babesiosis.
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Affiliation(s)
- Pallavi Singh
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Stefano Lonardi
- Department of Computer Science and Engineering, University of California, Riverside, CA, USA.
| | - Qihua Liang
- Department of Computer Science and Engineering, University of California, Riverside, CA, USA
| | - Pratap Vydyam
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | | | - Tiffany Fang
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Shalev Gihaz
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Jose Thekkiniath
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Muhammad Munshi
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA
| | - Steven Abel
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Loic Ciampossin
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Gayani Batugedara
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Mohit Gupta
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Xueqing Maggie Lu
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Todd Lenz
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA
| | - Sakshar Chakravarty
- Department of Computer Science and Engineering, University of California, Riverside, CA, USA
| | - Emmanuel Cornillot
- Institut de Biologie Computationnelle (IBC), and Institut de Recherche en Cancérologie de Montpellier (IRCM - INSERM U1194), Institut régional du Cancer Montpellier (ICM) and Université de Montpellier, Montpellier, France
| | - Yangyang Hu
- Department of Computer Science and Engineering, University of California, Riverside, CA, USA
| | - Wenxiu Ma
- Department of Statistics, University of California, Riverside, CA, USA
| | - Luis Miguel Gonzalez
- Parasitology Reference and Research Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Sergio Sánchez
- Reference and Research Laboratory on Food and Waterborne Bacterial Infections, National Centre for Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Karel Estrada
- Unidad Universitaria de Secuenciación Masiva y Bioinformática, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Alejandro Sánchez-Flores
- Unidad Universitaria de Secuenciación Masiva y Bioinformática, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Estrella Montero
- Parasitology Reference and Research Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Omar S Harb
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Karine G Le Roch
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, USA.
| | - Choukri Ben Mamoun
- Department of Internal Medicine, Section of Infectious Diseases, Yale School of Medicine, New Haven, CT, USA.
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Gupta A, Galinski MR, Voit EO. Dynamic Control Balancing Cell Proliferation and Inflammation is Crucial for an Effective Immune Response to Malaria. Front Mol Biosci 2022; 8:800721. [PMID: 35242812 PMCID: PMC8886244 DOI: 10.3389/fmolb.2021.800721] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 12/20/2021] [Indexed: 11/13/2022] Open
Abstract
Malaria has a complex pathology with varying manifestations and symptoms, effects on host tissues, and different degrees of severity and ultimate outcome, depending on the causative Plasmodium pathogen and host species. Previously, we compared the peripheral blood transcriptomes of two macaque species (Macaca mulatta and Macaca fascicularis) in response to acute primary infection by Plasmodium knowlesi. Although these two species are very closely related, the infection in M. mulatta is fatal, unless aggressively treated, whereas M. fascicularis develops a chronic, but tolerable infection in the blood. As a reason for this stark difference, our analysis suggests delayed pathogen detection in M. mulatta followed by extended inflammation that eventually overwhelms this monkey’s immune response. By contrast, the natural host M. fascicularis detects the pathogen earlier and controls the inflammation. Additionally, M. fascicularis limits cell proliferation pathways during the log phase of infection, presumably in an attempt to control inflammation. Subsequent cell proliferation suggests a cell-mediated adaptive immune response. Here, we focus on molecular mechanisms underlying the key differences in the host and parasite responses and their coordination. SICAvar Type 1 surface antigens are highly correlated with pattern recognition receptor signaling and important inflammatory genes for both hosts. Analysis of pathogen detection pathways reveals a similar signaling mechanism, but with important differences in the glutamate G-protein coupled receptor (GPCR) signaling pathway. Furthermore, differences in inflammasome assembly processes suggests an important role of S100 proteins in balancing inflammation and cell proliferation. Both differences point to the importance of Ca2+ homeostasis in inflammation. Additionally, the kynurenine-to-tryptophan ratio, a known inflammatory biomarker, emphasizes higher inflammation in M. mulatta during log phase. Transcriptomics-aided metabolic modeling provides a functional method for evaluating these changes and understanding downstream changes in NAD metabolism and aryl hydrocarbon receptor (AhR) signaling, with enhanced NAD metabolism in M. fascicularis and stronger AhR signaling in M. mulatta. AhR signaling controls important immune genes like IL6, IFNγ and IDO1. However, direct changes due to AhR signaling could not be established due to complicated regulatory feedback mechanisms associated with the AhR repressor (AhRR). A complete understanding of the exact dynamics of the immune response is difficult to achieve. Nonetheless, our comparative analysis provides clear suggestions of processes that underlie an effective immune response. Thus, our study identifies multiple points of intervention that are apparently responsible for a balanced and effective immune response and thereby paves the way toward future immune strategies for treating malaria.
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Affiliation(s)
- Anuj Gupta
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Mary R. Galinski
- Emory Vaccine Center, Yerkes National Primate Research Center, Department of Medicine, Division of Infectious Diseases, Emory University, Atlanta, GA, United States
| | - Eberhard O. Voit
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
- *Correspondence: Eberhard O. Voit,
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3
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Namvar A, Blanch AJ, Dixon MW, Carmo OMS, Liu B, Tiash S, Looker O, Andrew D, Chan LJ, Tham WH, Lee PVS, Rajagopal V, Tilley L. Surface area-to-volume ratio, not cellular viscoelasticity, is the major determinant of red blood cell traversal through small channels. Cell Microbiol 2020; 23:e13270. [PMID: 32981231 PMCID: PMC7757199 DOI: 10.1111/cmi.13270] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/14/2020] [Accepted: 09/18/2020] [Indexed: 12/12/2022]
Abstract
The remarkable deformability of red blood cells (RBCs) depends on the viscoelasticity of the plasma membrane and cell contents and the surface area to volume (SA:V) ratio; however, it remains unclear which of these factors is the key determinant for passage through small capillaries. We used a microfluidic device to examine the traversal of normal, stiffened, swollen, parasitised and immature RBCs. We show that dramatic stiffening of RBCs had no measurable effect on their ability to traverse small channels. By contrast, a moderate decrease in the SA:V ratio had a marked effect on the equivalent cylinder diameter that is traversable by RBCs of similar cellular viscoelasticity. We developed a finite element model that provides a coherent rationale for the experimental observations, based on the nonlinear mechanical behaviour of the RBC membrane skeleton. We conclude that the SA:V ratio should be given more prominence in studies of RBC pathologies.
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Affiliation(s)
- Arman Namvar
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia.,Department of Biomedical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - Adam J Blanch
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Matthew W Dixon
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Olivia M S Carmo
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Boyin Liu
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Snigdha Tiash
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Oliver Looker
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Dean Andrew
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Li-Jin Chan
- Division of Infection & Immunity, Walter & Eliza Hall Institute, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Wai-Hong Tham
- Division of Infection & Immunity, Walter & Eliza Hall Institute, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Peter V S Lee
- Department of Biomedical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - Vijay Rajagopal
- Department of Biomedical Engineering, University of Melbourne, Parkville, Victoria, Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
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Plasmodium genomics: an approach for learning about and ending human malaria. Parasitol Res 2018; 118:1-27. [PMID: 30402656 DOI: 10.1007/s00436-018-6127-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/19/2018] [Indexed: 12/31/2022]
Abstract
Malaria causes high levels of morbidity and mortality in human beings worldwide. According to the World Health Organization (WHO), about half a million people die of this disease each year. Malaria is caused by six species of parasites belonging to the Plasmodium genus: P. falciparum, P. knowlesi, P. vivax, P. malariae, P. ovale curtisi, and P. ovale wallikeri. Currently, malaria is being kept under control with varying levels of elimination success in different countries. The development of new molecular tools as well as the use of next-generation sequencing (NGS) technologies and novel bioinformatic approaches has improved our knowledge of malarial epidemiology, diagnosis, treatment, vaccine development, and surveillance strategies. In this work, the genetics and genomics of human malarias have been analyzed. Since the first P. falciparum genome was sequenced in 2002, various population-level genetic and genomic surveys, together with transcriptomic and proteomic studies, have shown the importance of molecular approaches in supporting malaria elimination.
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5
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Abstract
In the mosquito-human life cycle, the six species of malaria parasites infecting humans (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale wallickeri, Plasmodium ovale curtisi, Plasmodium malariae, and Plasmodium knowlesi) undergo 10 or more morphological states, replicate from single to 10,000+ cells, and vary in total population from one to many more than 106 organisms. In the human host, only a small number of these morphological stages lead to clinical disease and the vast majority of all malaria-infected patients in the world produce few (if any) symptoms in the human. Human clinical disease (e.g., fever, anemia, coma) is the result of the parasite preprogrammed biology in concert with the human pathophysiological response. Caveats and corollaries that add variation to this host-parasite interaction include parasite genetic diversity of key proteins, coinfections, comorbidities, delays in treatment, human polymorphisms, and environmental determinants.
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Affiliation(s)
- Danny A Milner
- Harvard T.H. Chan School of Public Health, American Society for Clinical Pathology, Center for Global Health, Chicago, Illinois 60603
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6
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Galinski MR, Lapp SA, Peterson MS, Ay F, Joyner CJ, LE Roch KG, Fonseca LL, Voit EO. Plasmodium knowlesi: a superb in vivo nonhuman primate model of antigenic variation in malaria. Parasitology 2018; 145:85-100. [PMID: 28712361 PMCID: PMC5798396 DOI: 10.1017/s0031182017001135] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/03/2017] [Accepted: 06/06/2017] [Indexed: 02/08/2023]
Abstract
Antigenic variation in malaria was discovered in Plasmodium knowlesi studies involving longitudinal infections of rhesus macaques (M. mulatta). The variant proteins, known as the P. knowlesi Schizont Infected Cell Agglutination (SICA) antigens and the P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) antigens, expressed by the SICAvar and var multigene families, respectively, have been studied for over 30 years. Expression of the SICA antigens in P. knowlesi requires a splenic component, and specific antibodies are necessary for variant antigen switch events in vivo. Outstanding questions revolve around the role of the spleen and the mechanisms by which the expression of these variant antigen families are regulated. Importantly, the longitudinal dynamics and molecular mechanisms that govern variant antigen expression can be studied with P. knowlesi infection of its mammalian and vector hosts. Synchronous infections can be initiated with established clones and studied at multi-omic levels, with the benefit of computational tools from systems biology that permit the integration of datasets and the design of explanatory, predictive mathematical models. Here we provide an historical account of this topic, while highlighting the potential for maximizing the use of P. knowlesi - macaque model systems and summarizing exciting new progress in this area of research.
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Affiliation(s)
- M R Galinski
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - S A Lapp
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - M S Peterson
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - F Ay
- La Jolla Institute for Allergy and Immunology,La Jolla,CA 92037,USA
| | - C J Joyner
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta,GA,USA
| | - K G LE Roch
- Department of Cell Biology & Neuroscience,Center for Disease and Vector Research,Institute for Integrative Genome Biology,University of California Riverside,CA 92521,USA
| | - L L Fonseca
- The Wallace H. Coulter Department of Biomedical Engineering,Georgia Institute of Technology and Emory University,Atlanta,Georgia,30332-2000,USA
| | - E O Voit
- The Wallace H. Coulter Department of Biomedical Engineering,Georgia Institute of Technology and Emory University,Atlanta,Georgia,30332-2000,USA
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7
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Lapp SA, Geraldo JA, Chien JT, Ay F, Pakala SB, Batugedara G, Humphrey J, DeBARRY JD, Le Roch KG, Galinski MR, Kissinger JC. PacBio assembly of a Plasmodium knowlesi genome sequence with Hi-C correction and manual annotation of the SICAvar gene family. Parasitology 2018; 145:71-84. [PMID: 28720171 PMCID: PMC5798397 DOI: 10.1017/s0031182017001329] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/09/2017] [Accepted: 06/20/2017] [Indexed: 12/20/2022]
Abstract
Plasmodium knowlesi has risen in importance as a zoonotic parasite that has been causing regular episodes of malaria throughout South East Asia. The P. knowlesi genome sequence generated in 2008 highlighted and confirmed many similarities and differences in Plasmodium species, including a global view of several multigene families, such as the large SICAvar multigene family encoding the variant antigens known as the schizont-infected cell agglutination proteins. However, repetitive DNA sequences are the bane of any genome project, and this and other Plasmodium genome projects have not been immune to the gaps, rearrangements and other pitfalls created by these genomic features. Today, long-read PacBio and chromatin conformation technologies are overcoming such obstacles. Here, based on the use of these technologies, we present a highly refined de novo P. knowlesi genome sequence of the Pk1(A+) clone. This sequence and annotation, referred to as the 'MaHPIC Pk genome sequence', includes manual annotation of the SICAvar gene family with 136 full-length members categorized as type I or II. This sequence provides a framework that will permit a better understanding of the SICAvar repertoire, selective pressures acting on this gene family and mechanisms of antigenic variation in this species and other pathogens.
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Affiliation(s)
- S A Lapp
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - J A Geraldo
- Federal University of Minas Gerais,Belo Horizonte, MG,Brazil
| | - J-T Chien
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - F Ay
- La Jolla Institute for Allergy and Immunology,La Jolla, CA 92037,USA
| | - S B Pakala
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - G Batugedara
- Center for Disease and Vector Research,Institute for Integrative Genome Biology,Department of Cell Biology & Neuroscience,University of California Riverside,CA 92521,USA
| | - J Humphrey
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - J D DeBARRY
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
| | - K G Le Roch
- Center for Disease and Vector Research,Institute for Integrative Genome Biology,Department of Cell Biology & Neuroscience,University of California Riverside,CA 92521,USA
| | - M R Galinski
- Emory Vaccine Center,Yerkes National Primate Research Center,Emory University,Atlanta, GA,USA
| | - J C Kissinger
- Institute of Bioinformatics, University of Georgia,Athens, GA 30602,USA
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Murphy JR, Weiss WR, Fryauff D, Dowler M, Savransky T, Stoyanov C, Muratova O, Lambert L, Orr-Gonzalez S, Zeleski KL, Hinderer J, Fay MP, Joshi G, Gwadz RW, Richie TL, Villasante EF, Richardson JH, Duffy PE, Chen J. Using infective mosquitoes to challenge monkeys with Plasmodium knowlesi in malaria vaccine studies. Malar J 2014; 13:215. [PMID: 24893777 PMCID: PMC4070636 DOI: 10.1186/1475-2875-13-215] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 03/03/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND When rhesus monkeys (Macaca mulatta) are used to test malaria vaccines, animals are often challenged by the intravenous injection of sporozoites. However, natural exposure to malaria comes via mosquito bite, and antibodies can neutralize sporozoites as they traverse the skin. Thus, intravenous injection may not fairly assess humoral immunity from anti-sporozoite malaria vaccines. To better assess malaria vaccines in rhesus, a method to challenge large numbers of monkeys by mosquito bite was developed. METHODS Several species and strains of mosquitoes were tested for their ability to produce Plasmodium knowlesi sporozoites. Donor monkey parasitaemia effects on oocyst and sporozoite numbers and mosquito mortality were documented. Methylparaben added to mosquito feed was tested to improve mosquito survival. To determine the number of bites needed to infect a monkey, animals were exposed to various numbers of P. knowlesi-infected mosquitoes. Finally, P. knowlesi-infected mosquitoes were used to challenge 17 monkeys in a malaria vaccine trial, and the effect of number of infectious bites on monkey parasitaemia was documented. RESULTS Anopheles dirus, Anopheles crascens, and Anopheles dirus X (a cross between the two species) produced large numbers of P. knowlesi sporozoites. Mosquito survival to day 14, when sporozoites fill the salivary glands, averaged only 32% when donor monkeys had a parasitaemia above 2%. However, when donor monkey parasitaemia was below 2%, mosquitoes survived twice as well and contained ample sporozoites in their salivary glands. Adding methylparaben to sugar solutions did not improve survival of infected mosquitoes. Plasmodium knowlesi was very infectious, with all monkeys developing blood stage infections if one or more infected mosquitoes successfully fed. There was also a dose-response, with monkeys that received higher numbers of infected mosquito bites developing malaria sooner. CONCLUSIONS Anopheles dirus, An. crascens and a cross between these two species all were excellent vectors for P. knowlesi. High donor monkey parasitaemia was associated with poor mosquito survival. A single infected mosquito bite is likely sufficient to infect a monkey with P. knowlesi. It is possible to efficiently challenge large groups of monkeys by mosquito bite, which will be useful for P. knowlesi vaccine studies.
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Spleen-dependent regulation of antigenic variation in malaria parasites: Plasmodium knowlesi SICAvar expression profiles in splenic and asplenic hosts. PLoS One 2013; 8:e78014. [PMID: 24205067 PMCID: PMC3799730 DOI: 10.1371/journal.pone.0078014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 09/16/2013] [Indexed: 02/04/2023] Open
Abstract
Background Antigenic variation by malaria parasites was first described in Plasmodium knowlesi, which infects humans and macaque monkeys, and subsequently in P. falciparum, the most virulent human parasite. The schizont-infected cell agglutination (SICA) variant proteins encoded by the SICAvar multigene family in P. knowlesi, and Erythrocyte Membrane Protein-1 (EMP-1) antigens encoded by the var multigene family in P. falciparum, are expressed at the surface of infected erythrocytes, are associated with virulence, and serve as determinants of naturally acquired immunity. A parental P. knowlesi clone, Pk1(A+), and a related progeny clone, Pk1(B+)1+, derived by an invivo induced variant antigen switch, were defined by the expression of distinct SICA variant protein doublets of 210/190 and 205/200 kDa, respectively. Passage of SICA[+] infected erythrocytes through splenectomized rhesus monkeys results in the SICA[-] phenotype, defined by the lack of surface expression and agglutination with variant specific antisera. Principal Findings We have investigated SICAvar RNA and protein expression in Pk1(A+), Pk1(B+)1+, and SICA[-] parasites. The Pk1(A+) and Pk1(B+)1+ parasites express different distinct SICAvar transcript and protein repertoires. By comparison, SICA[-] parasites are characterized by a vast reduction in SICAvar RNA expression, the lack of full-length SICAvar transcript signals on northern blots, and correspondingly, the absence of any SICA protein detected by mass spectrometry. Significance SICA protein expression may be under transcriptional as well as post-transcriptional control, and we show for the first time that the spleen, an organ central to blood-stage immunity in malaria, exerts an influence on these processes. Furthermore, proteomics has enabled the first in-depth characterization of SICA[+] protein phenotypes and we show that the invivo switch from Pk1(A+) to Pk1(B+)1+ parasites resulted in a complete change in SICA profiles. These results emphasize the importance of studying antigenic variation in the context of the host environment.
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10
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Lucchi NW, Poorak M, Oberstaller J, DeBarry J, Srinivasamoorthy G, Goldman I, Xayavong M, da Silva AJ, Peterson DS, Barnwell JW, Kissinger J, Udhayakumar V. A new single-step PCR assay for the detection of the zoonotic malaria parasite Plasmodium knowlesi. PLoS One 2012; 7:e31848. [PMID: 22363751 PMCID: PMC3282782 DOI: 10.1371/journal.pone.0031848] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 01/13/2012] [Indexed: 11/19/2022] Open
Abstract
Background Recent studies in Southeast Asia have demonstrated substantial zoonotic transmission of Plasmodium knowlesi to humans. Microscopically, P. knowlesi exhibits several stage-dependent morphological similarities to P. malariae and P. falciparum. These similarities often lead to misdiagnosis of P. knowlesi as either P. malariae or P. falciparum and PCR-based molecular diagnostic tests are required to accurately detect P. knowlesi in humans. The most commonly used PCR test has been found to give false positive results, especially with a proportion of P. vivax isolates. To address the need for more sensitive and specific diagnostic tests for the accurate diagnosis of P. knowlesi, we report development of a new single-step PCR assay that uses novel genomic targets to accurately detect this infection. Methodology and Significant Findings We have developed a bioinformatics approach to search the available malaria parasite genome database for the identification of suitable DNA sequences relevant for molecular diagnostic tests. Using this approach, we have identified multi-copy DNA sequences distributed in the P. knowlesi genome. We designed and tested several novel primers specific to new target sequences in a single-tube, non-nested PCR assay and identified one set of primers that accurately detects P. knowlesi. We show that this primer set has 100% specificity for the detection of P. knowlesi using three different strains (Nuri, H, and Hackeri), and one human case of malaria caused by P. knowlesi. This test did not show cross reactivity with any of the four human malaria parasite species including 11 different strains of P. vivax as well as 5 additional species of simian malaria parasites. Conclusions The new PCR assay based on novel P. knowlesi genomic sequence targets was able to accurately detect P. knowlesi. Additional laboratory and field-based testing of this assay will be necessary to further validate its utility for clinical diagnosis of P. knowlesi.
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Affiliation(s)
- Naomi W. Lucchi
- Atlanta Research and Education Foundation, Decatur, Georgia, United States of America
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Mitra Poorak
- Atlanta Research and Education Foundation, Decatur, Georgia, United States of America
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jenna Oberstaller
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Jeremy DeBarry
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - Ganesh Srinivasamoorthy
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - Ira Goldman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Maniphet Xayavong
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Alexandre J. da Silva
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - David S. Peterson
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
| | - John W. Barnwell
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jessica Kissinger
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, United States of America
- Institute of Bioinformatics, University of Georgia, Athens, Georgia, United States of America
| | - Venkatachalam Udhayakumar
- Atlanta Research and Education Foundation, Decatur, Georgia, United States of America
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
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