1
|
Peterson MS, Joyner CJ, Lapp SA, Brady JA, Wood JS, Cabrera-Mora M, Saney CL, Fonseca LL, Cheng WT, Jiang J, Soderberg SR, Nural MV, Hankus A, Machiah D, Karpuzoglu E, DeBarry JD, Tirouvanziam R, Kissinger JC, Moreno A, Gumber S, Voit EO, Gutierrez JB, Cordy RJ, Galinski MR. Plasmodium knowlesi Cytoadhesion Involves SICA Variant Proteins. Front Cell Infect Microbiol 2022; 12:888496. [PMID: 35811680 PMCID: PMC9260704 DOI: 10.3389/fcimb.2022.888496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/22/2022] [Indexed: 11/13/2022] Open
Abstract
Plasmodium knowlesi poses a health threat throughout Southeast Asian communities and currently causes most cases of malaria in Malaysia. This zoonotic parasite species has been studied in Macaca mulatta (rhesus monkeys) as a model for severe malarial infections, chronicity, and antigenic variation. The phenomenon of Plasmodium antigenic variation was first recognized during rhesus monkey infections. Plasmodium-encoded variant proteins were first discovered in this species and found to be expressed at the surface of infected erythrocytes, and then named the Schizont-Infected Cell Agglutination (SICA) antigens. SICA expression was shown to be spleen dependent, as SICA expression is lost after P. knowlesi is passaged in splenectomized rhesus. Here we present data from longitudinal P. knowlesi infections in rhesus with the most comprehensive analysis to date of clinical parameters and infected red blood cell sequestration in the vasculature of tissues from 22 organs. Based on the histopathological analysis of 22 tissue types from 11 rhesus monkeys, we show a comparative distribution of parasitized erythrocytes and the degree of margination of the infected erythrocytes with the endothelium. Interestingly, there was a significantly higher burden of parasites in the gastrointestinal tissues, and extensive margination of the parasites along the endothelium, which may help explain gastrointestinal symptoms frequently reported by patients with P. knowlesi malarial infections. Moreover, this margination was not observed in splenectomized rhesus that were infected with parasites not expressing the SICA proteins. This work provides data that directly supports the view that a subpopulation of P. knowlesi parasites cytoadheres and sequesters, likely via SICA variant antigens acting as ligands. This process is akin to the cytoadhesive function of the related variant antigen proteins, namely Erythrocyte Membrane Protein-1, expressed by Plasmodium falciparum.
Collapse
Affiliation(s)
- Mariko S. Peterson
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Chester J. Joyner
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Stacey A. Lapp
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Jessica A. Brady
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA, United States
| | - Jennifer S. Wood
- Division of Animal Resources, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States
| | - Monica Cabrera-Mora
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Celia L. Saney
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Luis L. Fonseca
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, United States
| | - Wayne T. Cheng
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
| | - Jianlin Jiang
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Stephanie R. Soderberg
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Mustafa V. Nural
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
| | - Allison Hankus
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Deepa Machiah
- Division of Pathology, Yerkes National Primate Research Center, Atlanta, GA, United States
| | - Ebru Karpuzoglu
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Jeremy D. DeBarry
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
| | - Rabindra Tirouvanziam
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States
| | - Jessica C. Kissinger
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, United States
- Institute of Bioinformatics, University of Georgia, Athens, GA, United States
- Department of Genetics, University of Georgia, Athens, GA, United States
| | - Alberto Moreno
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Sanjeev Gumber
- Division of Pathology, Yerkes National Primate Research Center, Atlanta, GA, United States
- Department of Pathology and Laboratory Medicine, Emory School of Medicine, 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
| | - Juan B. Gutierrez
- Department of Mathematics, University of Georgia, Athens, GA, United States
| | - Regina Joice Cordy
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
| | - Mary R. Galinski
- Emory National Primate Research Center, Emory University, Atlanta, GA, United States
- Emory Vaccine Center, Emory University, Atlanta, GA, United States
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
| |
Collapse
|
2
|
Transcriptome profiling of Plasmodium vivax in Saimiri monkeys identifies potential ligands for invasion. Proc Natl Acad Sci U S A 2019; 116:7053-7061. [PMID: 30872477 DOI: 10.1073/pnas.1818485116] [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: 12/13/2022] Open
Abstract
Unlike the case in Asia and Latin America, Plasmodium vivax infections are rare in sub-Saharan Africa due to the absence of the Duffy blood group antigen (Duffy antigen), the only known erythrocyte receptor for the P. vivax merozoite invasion ligand, Duffy binding protein 1 (DBP1). However, P. vivax infections have been documented in Duffy-negative individuals throughout Africa, suggesting that P. vivax may use ligands other than DBP1 to invade Duffy-negative erythrocytes through other receptors. To identify potential P. vivax ligands, we compared parasite gene expression in Saimiri and Aotus monkey erythrocytes infected with P. vivax Salvador I (Sal I). DBP1 binds Aotus but does not bind to Saimiri erythrocytes; thus, P. vivax Sal I must invade Saimiri erythrocytes independent of DBP1. Comparing RNA sequencing (RNAseq) data for late-stage infections in Saimiri and Aotus erythrocytes when invasion ligands are expressed, we identified genes that belong to tryptophan-rich antigen and merozoite surface protein 3 (MSP3) families that were more abundantly expressed in Saimiri infections compared with Aotus infections. These genes may encode potential ligands responsible for P. vivax infections of Duffy-negative Africans.
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Nunes-Silva S, Dechavanne S, Moussiliou A, Pstrąg N, Semblat JP, Gangnard S, Tuikue-Ndam N, Deloron P, Chêne A, Gamain B. Beninese children with cerebral malaria do not develop humoral immunity against the IT4-VAR19-DC8 PfEMP1 variant linked to EPCR and brain endothelial binding. Malar J 2015; 14:493. [PMID: 26646943 PMCID: PMC4672576 DOI: 10.1186/s12936-015-1008-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/21/2015] [Indexed: 11/16/2022] Open
Abstract
Background Malaria is still one of the most prevalent infectious diseases in the world. Sequestration of infected erythrocytes (IEs) is the prime mediator of disease. Cytoadhesion of IEs is mediated by members of the highly diverse Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). A restricted sub-set of var genes encoding for PfEMP1s possessing the domain cassettes DC8 and DC13 were found to bind to the endothelial protein C receptor (EPCR). These var genes were shown to be highly expressed by parasites from patients with severe malaria clinical outcomes compared to those from patients with uncomplicated symptoms. Methods In order to further study the molecular mechanisms underlying DC8/DC13 expressing IEs adhesion to EPCR, a method was developed to produce highly pure recombinant EPCR. The IT4 parasite strain was selected on either anti-IT4-VAR19 purified IgG, EPCR or human brain endothelial cell line and their var gene expression profiles as well as their binding phenotypes were compared. The N-terminal region of IT4-VAR19 comprising a full-length DC8 cassette as well as the single EPCR binding CIDRα1.1 domain were also produced, and their immune recognition (IgG) was assessed using plasma samples from Beninese children presenting acute mild malaria, severe malaria or cerebral malaria at the time of their admission to the clinic, and from convalescent-phase plasma collected 30 days after anti-malarial treatment. Results The multi-domain VAR19-NTS-DBLγ6 binds to EPCR with a greater affinity than the CIDRα1.1 domain alone and this study also demonstrates that VAR19-NTS-DBLγ6 binding to the EPCR-expressing endothelial cell line (HBEC5i) is more pronounced than that of the CIDRα1.1 domain alone. IT4-VAR19 represents the preferentially expressed-PfEMP1 when FCR3-IEs are selected based on their capability to bind EPCR. Notably, no significant difference in the levels of antibodies towards IT4-VAR19 antigens was observed within all clinical groups between plasma samples collected during the acute malaria phase compared to samples collected 30 days after anti-malaria treatment. Conclusions These data indicate that even being the preferentially selected IT4-EPCR-binding variant, the IT4-VAR19-DC8 region does not appear to be associated with the acquisition of antibodies during a single severe paediatric malaria episode in Benin. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1008-5) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Sofia Nunes-Silva
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Sébastien Dechavanne
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Azizath Moussiliou
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Natalia Pstrąg
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Jean-Philippe Semblat
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Stéphane Gangnard
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Nicaise Tuikue-Ndam
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Philippe Deloron
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Arnaud Chêne
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Benoît Gamain
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| |
Collapse
|
5
|
Alves FA, Pelajo-Machado M, Totino PRR, Souza MT, Gonçalves EC, Schneider MPC, Muniz JAPC, Krieger MA, Andrade MCR, Daniel-Ribeiro CT, Carvalho LJM. Splenic architecture disruption and parasite-induced splenocyte activation and anergy in Plasmodium falciparum-infected Saimiri sciureus monkeys. Malar J 2015; 14:128. [PMID: 25890318 PMCID: PMC4377215 DOI: 10.1186/s12936-015-0641-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/06/2015] [Indexed: 11/15/2022] Open
Abstract
Background The understanding of the mechanisms of immunity in malaria is crucial for the rational development of interventions such as vaccines. During blood stage infection, the spleen is considered to play critical roles in both immunity and immunopathology of Plasmodium falciparum infections. Methods Saimiri sciureus monkeys were inoculated with blood stages of P. falciparum (FUP strain) and spleens removed during acute disease (days 7 and 13 of infection) and during convalescence (15 days after start of chloroquine treatment). Cytokine (IFNγ, TNFα, IL2, IL6, IL10, and IL12) responses of splenocytes stimulated with P. falciparum-parasitized red blood cells were assessed by real-time PCR using specific Saimiri primers, and histological changes were evaluated using haematoxylin-eosin and Giemsa-stained slides. Results Early during infection (day 7, 1-2% parasitaemia), spleens showed disruption of germinal centre architecture with heavy B-cell activation (centroblasts), and splenocytes showed increased expression of IFNγ, IL6 and IL12 upon in vitro stimuli by P. falciparum-parasitized red blood cells (pRBC). Conversely, 15 days after treatment of blood stage infection with chloroquine, splenocytes showed spontaneous in vitro expression of TNFα, IL2, IL6, IL10, and IL12, but not IFNγ, and stimulation with P. falciparum pRBC blocked the expression of all these cytokines. During the acute phase of infection, splenic disarray with disorganized germinal centres was observed. During convalescence, spleens of the chloroquine-treated animals showed white pulp hyperplasia with extensive lymphocyte activation and persistency of heavily haemozoin-laden macrophages throughout the red pulp. Conclusions Inability to eliminate haemozoin is likely involved in the persistent lymphocyte activation and in the anergic responses of Saimiri splenocytes to P. falciparum pRBC, with important negative impact in immune responses and implications for the design of malaria vaccine.
Collapse
Affiliation(s)
- Francisco A Alves
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil. .,Laboratório de Imunobiologia, Universidade Federal do Pará (UFPA), Belém, Brazil.
| | - Marcelo Pelajo-Machado
- Laboratório de Patologia, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil.
| | - Paulo R R Totino
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil.
| | - Mariana T Souza
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil.
| | - Evonnildo C Gonçalves
- Laboratório de Tecnologia Biomolecular, Universidade Federal do Pará (UFPA), Belém, Brazil.
| | | | | | - Marco A Krieger
- Instituto Carlos Chagas de Biologia Molecular, Curitiba, Brazil.
| | - Marcia C R Andrade
- Serviço de Criação de Primatas Não-Humanos, CECAL-Fiocruz, Rio de Janeiro, Brazil.
| | | | - Leonardo J M Carvalho
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil.
| |
Collapse
|
6
|
Llama immunization with full-length VAR2CSA generates cross-reactive and inhibitory single-domain antibodies against the DBL1X domain. Sci Rep 2014; 4:7373. [PMID: 25487735 PMCID: PMC5376981 DOI: 10.1038/srep07373] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022] Open
Abstract
VAR2CSA stands today as the leading vaccine candidate aiming to protect future pregnant women living in malaria endemic areas against the severe clinical outcomes of pregnancy associated malaria (PAM). The rational design of an efficient VAR2CSA-based vaccine relies on a profound understanding of the molecular interactions associated with P. falciparum infected erythrocyte sequestration in the placenta. Following immunization of a llama with the full-length VAR2CSA recombinant protein, we have expressed and characterized a panel of 19 nanobodies able to recognize the recombinant VAR2CSA as well as the surface of erythrocytes infected with parasites originating from different parts of the world. Domain mapping revealed that a large majority of nanobodies targeted DBL1X whereas a few of them were directed towards DBL4ε, DBL5ε and DBL6ε. One nanobody targeting the DBL1X was able to recognize the native VAR2CSA protein of the three parasite lines tested. Furthermore, four nanobodies targeting DBL1X reproducibly inhibited CSA adhesion of erythrocytes infected with the homologous NF54-CSA parasite strain, providing evidences that DBL1X domain is part or close to the CSA binding site. These nanobodies could serve as useful tools to identify conserved epitopes shared between different variants and to characterize the interactions between VAR2CSA and CSA.
Collapse
|
7
|
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.
Collapse
|
8
|
Warimwe GM, Fegan G, Musyoki JN, Newton CR, Opiyo M, Githinji G, Andisi C, Menza F, Kitsao B, Marsh K, Bull PC. Prognostic indicators of life-threatening malaria are associated with distinct parasite variant antigen profiles. Sci Transl Med 2012; 4:129ra45. [PMID: 22496547 PMCID: PMC3491874 DOI: 10.1126/scitranslmed.3003247] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PfEMP1 is a family of cytoadhesive surface antigens expressed on erythrocytes infected with Plasmodium falciparum, the parasite that causes the most severe form of malaria. These surface antigens play a role in immune evasion and are thought to contribute to the pathogenesis of the malaria parasite. Previous studies have suggested a role for a specific subset of PfEMP1 called "group A" in severe malaria. To explore the role of group A PfEMP1 in disease, we measured the expression of the var genes that encode them in parasites from clinical isolates collected from children suffering from malaria. We also looked at the ability of these clinical isolates to induce rosetting of erythrocytes, which indicates a cytoadhesion phenotype that is thought to be important in pathogenesis. These two sets of data were correlated with the presence of two life-threatening manifestations of severe malaria in the children: impaired consciousness and respiratory distress. Using regression analysis, we show that marked rosetting was associated with respiratory distress, whereas elevated expression of group A-like var genes without elevated rosetting was associated with impaired consciousness. The results suggest that manifestations of malarial disease may reflect the distribution of cytoadhesion phenotypes expressed by the infecting parasite population.
Collapse
Affiliation(s)
- George M. Warimwe
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Gregory Fegan
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
- Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - Jennifer N. Musyoki
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Charles R.J.C. Newton
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Michael Opiyo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - George Githinji
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Cheryl Andisi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Francis Menza
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Barnes Kitsao
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
| | - Kevin Marsh
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
- Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| | - Peter C. Bull
- Kenya Medical Research Institute-Wellcome Trust Research Programme, P.O. Box 230-80108 Kilifi, Kenya
- Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, UK
| |
Collapse
|
9
|
Abstract
In the burgeoning field of Plasmodium gene expression, there are--to borrow some famous words from a former U.S. Secretary of Defense--"known knowns, known unknowns, and unknown unknowns." This is in itself an important achievement, since it is only in the past decade that facts have begun to move from the third category into the first. Nevertheless, much remains in the middle ground of known or suspected "unknowns." It is clear that the malaria parasite controls vital virulence processes such as host cell invasion and cytoadherence at least partly via epigenetic mechanisms, so a proper understanding of epigenetic transcriptional control in this organism should have great clinical relevance. Plasmodium, however, is an obligate intracellular parasite: it operates not in a vacuum but rather in the complicated context of its metazoan hosts. Therefore, as valuable data about the parasite's basic epigenetic machinery begin to emerge, it becomes increasingly important to relate in vitro studies to the situation in vivo. This review will focus upon the challenge of understanding Plasmodium epigenetics in an integrated manner, in the human and insect hosts as well as the petri dish.
Collapse
|
10
|
Mackinnon MJ, Li J, Mok S, Kortok MM, Marsh K, Preiser PR, Bozdech Z. Comparative transcriptional and genomic analysis of Plasmodium falciparum field isolates. PLoS Pathog 2009; 5:e1000644. [PMID: 19898609 PMCID: PMC2764095 DOI: 10.1371/journal.ppat.1000644] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 10/05/2009] [Indexed: 11/18/2022] Open
Abstract
Mechanisms for differential regulation of gene expression may underlie much of the phenotypic variation and adaptability of malaria parasites. Here we describe transcriptional variation among culture-adapted field isolates of Plasmodium falciparum, the species responsible for most malarial disease. It was found that genes coding for parasite protein export into the red cell cytosol and onto its surface, and genes coding for sexual stage proteins involved in parasite transmission are up-regulated in field isolates compared with long-term laboratory isolates. Much of this variability was associated with the loss of small or large chromosomal segments, or other forms of gene copy number variation that are prevalent in the P. falciparum genome (copy number variants, CNVs). Expression levels of genes inside these segments were correlated to that of genes outside and adjacent to the segment boundaries, and this association declined with distance from the CNV boundary. This observation could not be explained by copy number variation in these adjacent genes. This suggests a local-acting regulatory role for CNVs in transcription of neighboring genes and helps explain the chromosomal clustering that we observed here. Transcriptional co-regulation of physical clusters of adaptive genes may provide a way for the parasite to readily adapt to its highly heterogeneous and strongly selective environment.
Collapse
|
11
|
Abstract
More attention is being focused on malaria today than any time since the world's last efforts to achieve eradication over 40 years ago. The global community is now discussing strategies aimed at dramatically reducing malarial disease burden and the eventual eradication of all types of malaria, everywhere. As a consequence, Plasmodium vivax, which has long been neglected and mistakenly considered inconsequential, is now entering into the strategic debates taking place on malaria epidemiology and control, drug resistance, pathogenesis and vaccines. Thus, contrary to the past, the malaria research community is becoming more aware and concerned about the widespread spectrum of illness and death caused by up to a couple of hundred million cases of vivax malaria each year. This review brings these issues to light and provides an overview of P. vivax vaccine development, then and now. Progress had been slow, given inherent research challenges and minimal support in the past, but prospects are looking better for making headway in the next few years. P. vivax, known to invade the youngest red blood cells, the reticulocytes, presents a strong challenge towards developing a reliable long-term culture system to facilitate needed research. The P. vivax genome was published recently, and vivax researchers now need to coordinate efforts to discover new vaccine candidates, establish new vaccine approaches, capitalize on non-human primate models for testing, and investigate the unique biological features of P. vivax, including the elusive P. vivax hypnozoites. Comparative studies on both P. falciparum and P. vivax in many areas of research will be essential to eradicate malaria. And to this end, the education and training of future generations of dedicated "malariologists" to advance our knowledge, understanding and the development of new interventions against each of the malaria species infecting humans also will be essential.
Collapse
Affiliation(s)
- Mary R Galinski
- Emory Vaccine Center and Yerkes National Primate Research Center, Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Atlanta, GA, USA
| | - John W Barnwell
- Malaria Branch, Division of Parasitic Diseases, National Center for Zoonotic, Vector-Borne and Enteric Diseases, the Centers for Disease Control and Prevention, Atlanta, GA, USA
| |
Collapse
|
12
|
Mok BW, Ribacke U, Rasti N, Kironde F, Chen Q, Nilsson P, Wahlgren M. Default Pathway of var2csa switching and translational repression in Plasmodium falciparum. PLoS One 2008; 3:e1982. [PMID: 18431472 PMCID: PMC2292259 DOI: 10.1371/journal.pone.0001982] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 03/02/2008] [Indexed: 11/19/2022] Open
Abstract
Antigenic variation is a subtle process of fundamental importance to the survival of a microbial pathogen. In Plasmodium falciparum malaria, PfEMP1 is the major variable antigen and adhesin expressed at the surface of the infected erythrocyte, which is encoded for by members of a family of 60 var-genes. Peri-nuclear repositioning and epigenetic mechanisms control their mono-allelic expression. The switching of PfEMP1 depends in part on variable transition rates and short-lived immune responses to shared minor epitopes. Here we show var-genes to switch to a common gene that is highly transcribed, but sparsely translated into PfEMP1 and not expressed at the erythrocyte surface. Highly clonal and adhesive P. falciparum, which expressed distinct var-genes and the corresponding PfEMP1s at onset, were propagated without enrichment or panning. The parasites successively and spontaneously switched to transcribe a shared var-gene (var2csa) matched by the loss of PfEMP1 surface expression and host cell-binding. The var2csa gene repositioned in the peri-nuclear area upon activation, away from the telomeric clusters and heterochromatin to transcribe spliced, full-length RNA. Despite abundant transcripts, the level of intracellular PfEMP1 was low suggesting post-transcriptional mechanisms to partake in protein expression. In vivo, off-switching and translational repression may constitute one pathway, among others, coordinating PfEMP1 expression.
Collapse
Affiliation(s)
- Bobo W. Mok
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Niloofar Rasti
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Fred Kironde
- Department of Biochemistry, Faculty of Medicine, Makerere University, Kampala, Uganda
| | - Qijun Chen
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Peter Nilsson
- Department of Gene Technology, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
- * E-mail:
| |
Collapse
|
13
|
Mackinnon MJ, Read AF. Virulence in malaria: an evolutionary viewpoint. Philos Trans R Soc Lond B Biol Sci 2004; 359:965-86. [PMID: 15306410 PMCID: PMC1693375 DOI: 10.1098/rstb.2003.1414] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Malaria parasites cause much morbidity and mortality to their human hosts. From our evolutionary perspective, this is because virulence is positively associated with parasite transmission rate. Natural selection therefore drives virulence upwards, but only to the point where the cost to transmission caused by host death begins to outweigh the transmission benefits. In this review, we summarize data from the laboratory rodent malaria model, Plasmodium chabaudi, and field data on the human malaria parasite, P. falciparum, in relation to this virulence trade-off hypothesis. The data from both species show strong positive correlations between asexual multiplication, transmission rate, infection length, morbidity and mortality, and therefore support the underlying assumptions of the hypothesis. Moreover, the P. falciparum data show that expected total lifetime transmission of the parasite is maximized in young children in whom the fitness cost of host mortality balances the fitness benefits of higher transmission rates and slower clearance rates, thus exhibiting the hypothesized virulence trade-off. This evolutionary explanation of virulence appears to accord well with the clinical and molecular explanations of pathogenesis that involve cytoadherence, red cell invasion and immune evasion, although direct evidence of the fitness advantages of these mechanisms is scarce. One implication of this evolutionary view of virulence is that parasite populations are expected to evolve new levels of virulence in response to medical interventions such as vaccines and drugs.
Collapse
Affiliation(s)
- Margaret J Mackinnon
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
| | | |
Collapse
|
14
|
Mackinnon MJ, Read AF. Immunity promotes virulence evolution in a malaria model. PLoS Biol 2004; 2:E230. [PMID: 15221031 PMCID: PMC434153 DOI: 10.1371/journal.pbio.0020230] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Accepted: 05/25/2004] [Indexed: 11/19/2022] Open
Abstract
Evolutionary models predict that host immunity will shape the evolution of parasite virulence. While some assumptions of these models have been tested, the actual evolutionary outcome of immune selection on virulence has not. Using the mouse malaria model, Plasmodium chabaudi, we experimentally tested whether immune pressure promotes the evolution of more virulent pathogens by evolving parasite lines in immunized and nonimmunized ("naïve") mice using serial passage. We found that parasite lines evolved in immunized mice became more virulent to both naïve and immune mice than lines evolved in naïve mice. When these evolved lines were transmitted through mosquitoes, there was a general reduction in virulence across all lines. However, the immune-selected lines remained more virulent to naïve mice than the naïve-selected lines, though not to immunized mice. Thus, immune selection accelerated the rate of virulence evolution, rendering parasites more dangerous to naïve hosts. These results argue for further consideration of the evolutionary consequences for pathogen virulence of vaccination.
Collapse
Affiliation(s)
- Margaret J Mackinnon
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
| | | |
Collapse
|
15
|
Abstract
Many pathogens that either rely on an insect vector to complete their life cycle (e.g., Trypanosoma spp. and Borrelia spp.) or exist in a unique ecological niche where transmission from host to host is sporadic (e.g., Neisseria spp.) have evolved strategies to maintain infection of their mammalian hosts for long periods of time in order to ensure their survival. Because they have to survive in the face of a fully functional immune system, a common feature of many of these organisms is their development of sophisticated strategies for immune evasion. For the above organisms and for malaria parasites of the genus Plasmodium, a common theme is the ability to undergo clonal antigenic variation. In all cases, surface molecules that are important targets of the humoral immune response are encoded in the genome as multicopy, nonallelic gene families. Antigenic variation is accomplished by the successive expression of members of these gene families that show little or no immunological cross-reactivity. In the case of malaria parasites, however, some of the molecules that undergo antigenic variation are also major virulence factors, adding an additional level of complication to the host-parasite interaction. In this review, we cover the history of antigenic variation in malaria and then summarize the more recent data with particular emphasis on Plasmodium falciparum, the etiological agent of the most severe form of human malaria.
Collapse
Affiliation(s)
- S Kyes
- Molecular Parasitology Group, Weatherall Institute of Molecular Medicine, Headington, Oxford OX3 9DS United Kingdom.
| | | | | |
Collapse
|
16
|
Lanzer M, de Bruin D, Wertheimer SP, Ravetch JV. Transcriptional and nucleosomal characterization of a subtelomeric gene cluster flanking a site of chromosomal rearrangements in Plasmodium falciparum. Nucleic Acids Res 1994; 22:4176-82. [PMID: 7937144 PMCID: PMC331913 DOI: 10.1093/nar/22.20.4176] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have recently demonstrated that Plasmodium falciparum chromosomes are compartmentalized into different domains: conserved and polymorphic domains; transcriptionally active and silent domains. Here we have analyzed the transition between these domains at the structural and nucleosomal level. This study was conducted with the end of chromosome 2 that is associated with cytoadherence. At this end of the chromosome, the first set of erythrocytic genes has been mapped 85 kb from the telomere. These genes are monocistronically transcribed as revealed by nuclear run-on analysis. Two of these genes, PfEMP3 and KAHRP, are deleted in cytoadherent negative mutants, whereas the third gene, GLARP, is expressed in all the strains investigated. The data indicate that the polymorphic domain at this end of chromosome 2 extends into the transcribed region. Analysis of the chromatin structure revealed that both the transcribed domain and the subtelomeric region are organized as nucleosomes with a periodicity of 155 +/- 5 bp.
Collapse
Affiliation(s)
- M Lanzer
- Zentrum für Infektionsforschung, Universität Würzburg, Germany
| | | | | | | |
Collapse
|
17
|
Lanzer M, de Bruin D, Ravetch JV. A sequence element associated with the Plasmodium falciparum KAHRP gene is the site of developmentally regulated protein-DNA interactions. Nucleic Acids Res 1992; 20:3051-6. [PMID: 1620601 PMCID: PMC312436 DOI: 10.1093/nar/20.12.3051] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The Plasmodium falciparum gene encoding the knob associated histidine-rich protein (KAHRP) is shown to be transcriptionally regulated during its expression in the intraerythrocytic cycle as demonstrated by stage specific nuclear run-on analysis. The genomic organization of the KAHRP gene was determined and the structural basis for the stage specific transcription investigated. A sequence motif with two-fold symmetry was found 160 bp upstream of the RNA initiation site. This sequence element interacts with parasite derived nuclear extracts in a stage specific manner that correlates with the transcriptional activity of the KAHRP gene. These studies suggest a functional role for this structural element in the developmental regulation of a P. falciparum erythrocytic gene.
Collapse
Affiliation(s)
- M Lanzer
- DeWitt Wallace Research Laboratory, Division of Molecular Biology, Sloan-Kettering Institute, New York, NY 10021
| | | | | |
Collapse
|
18
|
Ho M, Bannister LH, Looareesuwan S, Suntharasamai P. Cytoadherence and ultrastructure of Plasmodium falciparum-infected erythrocytes from a splenectomized patient. Infect Immun 1992; 60:2225-8. [PMID: 1587590 PMCID: PMC257147 DOI: 10.1128/iai.60.6.2225-2228.1992] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In malarial infections of primates, the spleen has been shown to modulate parasite antigen expression on the surfaces of infected erythrocytes. The processes affected include cytoadherence, which is central to the pathophysiology of severe falciparum malaria, and the related phenomenon of rosette formation. In this study, the cytoadherence and rosette formation behaviors of Plasmodium falciparum-infected erythrocytes from a splenectomized patient were examined during the first erythrocytic cycle in vitro. Ultrastructural studies were also performed. Infected erythrocytes were found to cytoadhere to C32 melanoma cells via leukocyte differentiation antigen CD36 but not intercellular adhesion molecule 1. They also displayed on their surfaces electron-dense knobs similar in structure and density to those on infected erythrocytes from intact hosts. These findings may reflect a stable cytoadherent phenotype of the parasite isolate that is unaffected by the absence of the spleen. Alternatively, the modulating role of the spleen may have been assumed by other organs of the mononuclear phagocytic system in a previously infected individual. No rosette formation was observed, but as not all natural isolates form rosettes, this observation may or may not be related to the asplenic status of the patient. Parasite and host factors appear to be important in determining the effect of splenectomy on cytoadherence and rosette formation in human falciparum malaria.
Collapse
Affiliation(s)
- M Ho
- Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | | | | |
Collapse
|
19
|
Barnwell JW, Asch AS, Nachman RL, Yamaya M, Aikawa M, Ingravallo P. A human 88-kD membrane glycoprotein (CD36) functions in vitro as a receptor for a cytoadherence ligand on Plasmodium falciparum-infected erythrocytes. J Clin Invest 1989; 84:765-72. [PMID: 2474574 PMCID: PMC329717 DOI: 10.1172/jci114234] [Citation(s) in RCA: 273] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Plasmodium falciparum-infected erythrocytes (IE) specifically adhere to vascular endothelium in vivo and to human endothelial cells, some human melanoma cell lines, and human monocytes in vitro. The tissue cell receptor for a ligand on the surface of the infected erythrocytes is an Mr 88,000 glycoprotein (GP88) recognized by the MAb OKM5, which also blocks cytoadherence of IE. Isolated, affinity-purified GP88 (CD36) competitively blocks cytoadherence and when absorbed to plastic surfaces, specifically binds P. falciparum IE. Additionally, monoclonal and polyclonal antibodies to GP88 block cytoadherence to both target cells and immobilized GP88. Binding to GP88 by IE is unaffected by the absence of calcium or the absence of thrombospondin, a putative mediator for cytoadherence of P. falciparum IE. Thus, GP88 (CD36), which has been demonstrated to be the same as platelet glycoprotein IV, interacts directly with P. falciparum IE, presumably via a parasite-induced ligand exposed on the surface of the infected erythrocytes. CD36 is shown to be present on brain endothelium in both individuals without malaria and individuals with cerebral malaria. This would suggest that factors other than just cerebral sequestration of IE play an initiating role in the genesis of cerebral malaria.
Collapse
Affiliation(s)
- J W Barnwell
- Department of Medical and Molecular Parasitology, New York University Medical School 10010
| | | | | | | | | | | |
Collapse
|
20
|
Panton LJ, Leech JH, Miller LH, Howard RJ. Cytoadherence of Plasmodium falciparum-infected erythrocytes to human melanoma cell lines correlates with surface OKM5 antigen. Infect Immun 1987; 55:2754-8. [PMID: 3312010 PMCID: PMC259972 DOI: 10.1128/iai.55.11.2754-2758.1987] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
OKM5 antigen and thrombospondin are currently under investigation as potential receptors on the surface of human monocytes, endothelial cells, and melanomas responsible for the cytoadherence of Plasmodium falciparum-infected erythrocytes. We have studies the binding capacity of six human melanoma cell lines and related this property to the cytoplasmic and surface expression of the OKM5 antigen and thrombospondin by using indirect immunofluorescence assays on methanol-fixed and nonfixed melanomas. The presence of OKM5 antigen was detectable only in the melanoma lines which bound P. falciparum-infected erythrocytes. Thrombospondin was present in the cytoplasm of all the melanoma lines but was not detectable on the surface of any cells. Our work demonstrates a direct correlation between surface OKM5 antigen and cytoadherence in vitro. While our results do not exclude thrombospondin as a mediator of cytoadherence to endothelial cells in vivo, they showed no correlation between the presence of thrombospondin and the ability of melanoma cell lines to cytoadhere in vitro.
Collapse
Affiliation(s)
- L J Panton
- Malaria Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892
| | | | | | | |
Collapse
|
21
|
Aley SB, Sherwood JA, Howard RJ. Knob-positive and knob-negative Plasmodium falciparum differ in expression of a strain-specific malarial antigen on the surface of infected erythrocytes. J Exp Med 1984; 160:1585-90. [PMID: 6208311 PMCID: PMC2187501 DOI: 10.1084/jem.160.5.1585] [Citation(s) in RCA: 147] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We have investigated the expression of a strain-specific malarial antigen on the surface of erythrocytes infected with knobless (K-) variants of knob-positive (K+) strains of Plasmodium falciparum. Aotus blood infected with K+ or K- parasites derived from two independent geographical isolates (Malayan camp and Santa Lucia) was surface iodinated by the lactoperoxidase method. Infected and uninfected erythrocytes were then separated by a new procedure involving equilibrium density sedimentation on a Percoll gradient containing sorbitol. Strain-specific antigens were readily identified on the surface of erythrocytes infected with either of the K+ strains by their characteristic size and detergent solubility. These proteins were not detected on the surface of erythrocytes infected with either of the K- variants nor on uninfected erythrocytes isolated from K+- or K- -infected blood. These results are consistent with a role for the strain-specific surface antigen in cytoadherence of P. falciparum-infected erythrocytes. Our findings represent the second biochemical difference (with the knob-associated histidine-rich protein) between K+ and K- P. falciparum.
Collapse
|
22
|
Howard RJ, Barnwell JW, Kao V. Antigenic variation of Plasmodium knowlesi malaria: identification of the variant antigen on infected erythrocytes. Proc Natl Acad Sci U S A 1983; 80:4129-33. [PMID: 6191331 PMCID: PMC394214 DOI: 10.1073/pnas.80.13.4129] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Erythrocytes infected with mature asexual stages of Plasmodium knowlesi express a new surface antigen such that rhesus monkey antisera specifically agglutinate these cells. Cloned parasites can express different antigenic variants of this antigen. The variant antigen has been identified by comparison of the surface membrane antigens of a clone and of an antigenic variant of that clone of different agglutination phenotype. After lactoperoxidase labeling, 125I-labeled proteins of Mrs 210,000 and 190,000 with one clone and of Mrs 205,000 with the antigenic variant were only immunoprecipitated by antisera containing homologous anti-variant antibody. Antigens of the same Mr from each clone were labeled by [35S]methionine incorporation during parasite growth and also specifically immunoprecipitated only by agglutinating antisera. Therefore, the variant antigens are malarial proteins rather than modified host proteins.
Collapse
|