scholarly journals Neonatal and Maternal Immunological Responses to Conserved Epitopes within the DBL-γ3 Chondroitin Sulfate A-Binding Domain of Plasmodium falciparum Erythrocyte Membrane Protein 1

2005 ◽  
Vol 73 (12) ◽  
pp. 7988-7995 ◽  
Author(s):  
Kim Brustoski ◽  
Martin Kramer ◽  
Ulrike Möller ◽  
Peter G. Kremsner ◽  
Adrian J. F. Luty
Keyword(s):  
T Cells ◽  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Chondroitin Sulfate ◽  
Erythrocyte Membrane ◽  
Venous Blood ◽  
Binding Domain ◽  
Erythrocyte Membrane Protein ◽  
Conserved Regions ◽  
Chondroitin Sulfate A

ABSTRACT Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates the adherence of P. falciparum-infected erythrocytes to placental syncytiotrophoblasts via interactions with chondroitin sulfate A (CSA), a characteristic of pregnancy-associated malaria. Pregnancy-associated malaria predicts increased susceptibility of newborns to malaria, and it is postulated that transplacental passage of parasite antigen induces immune regulatory activity in the neonate. We wished to examine the immune responsiveness to a CSA-binding domain of PfEMP1, the DBL-γ3 domain, in cord and maternal venous blood obtained from pregnancies with various histories of P. falciparum infection. We assessed in vitro T-cell cytokine and plasma immunoglobulin G (IgG) and IgM responses to four peptides corresponding to highly conserved regions of a DBL-γ3 domain common to central African parasite isolates. The presence of placental P. falciparum infection at delivery was associated with elevated frequencies of DBL-γ3 peptide-specific CD3+ interleukin-10-positive T cells in cord blood, while treatment and clearance of infection prior to delivery was associated with elevated frequencies of CD3+ gamma interferon-positive T cells. DBL-γ3 peptide-specific IgM antibodies were detected in 12 of 60 (20%) cord plasma samples from those born to mothers with P. falciparum infection during pregnancy. Consistent with polyclonal anti-PfEMP1 antibody responses that are associated with protection against pregnancy-associated malaria, the presence of maternal IgG antibodies with specificity for one of the DBL-γ3 peptides showed a parity-dependent profile. These data demonstrate that peptides corresponding to conserved regions of the DBL-γ3 domain of PfEMP1 are immunogenic in P. falciparum-infected mothers and their offspring.

scholarly journals Identification of Glycosaminoglycan Binding Domains in Plasmodium falciparum Erythrocyte Membrane Protein 1 of a Chondroitin Sulfate A-Adherent Parasite

2000 ◽  
Vol 68 (7) ◽  
pp. 3923-3926 ◽  
Author(s):  
John C. Reeder ◽  
Anthony N. Hodder ◽  
James G. Beeson ◽  
Graham V. Brown
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Chondroitin Sulfate ◽  
Erythrocyte Membrane ◽  
Binding Activity ◽  
Parasite Line ◽  
Erythrocyte Membrane Protein ◽  
Binding Domains ◽  
Nonlinear Binding ◽  
Chondroitin Sulfate A

ABSTRACT Accumulation of Plasmodium falciparum-infected erythrocytes in the placenta is a key feature of maternal malaria. This process is mediated in part by the parasite ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1) at the surface of the infected erythrocyte interacting with the host receptor chondroitin sulfate A (CSA) on the placental lining. We have localized CSA binding activity to two adjacent domains in PfEMP1 of an adherent parasite line and shown the presence of at least three active glycosaminoglycan binding sites. A putative CSA binding sequence was identified in one domain, but nonlinear binding motifs are also likely to be present, since binding activity in the region was shown to be dependent on conformation. Characterization of this binding region provides an opportunity to investigate further its potential as a target for antiadhesion therapy.

scholarly journals Identification of VAR2CSA Domain-Specific Inhibitory Antibodies of the Plasmodium falciparum Erythrocyte Membrane Protein 1 Using a Novel Flow Cytometry Assay

2013 ◽  
Vol 20 (3) ◽  
pp. 433-442 ◽  
Author(s):  
Harold Obiakor ◽  
Marion Avril ◽  
Nicholas J. MacDonald ◽  
Prakash Srinivasan ◽  
Karine Reiter ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Chondroitin Sulfate ◽  
Erythrocyte Membrane ◽  
Recombinant Proteins ◽  
Binding Assay ◽  
Content Type ◽  
Erythrocyte Membrane Protein ◽  
First Time

ABSTRACTVAR2CSA, a member of thePlasmodium falciparumerythrocyte membrane protein 1 (PfEMP1) family, is a leading candidate for use in vaccines to protect first-time mothers from placental malaria (PM). VAR2CSA, which is comprised of a series of six Duffy binding-like (DBL) domains, binds chondroitin sulfate A (CSA) on placental syncytiotrophoblast. Several recombinant DBL domains have been shown to bind CSA. In order to identify and develop recombinant proteins suitable for clinical development, DBL2X and DBL3X, as well as their respective third subdomain (S3) from the FCR3 parasite clone, were expressed inEscherichia coli, refolded, and purified. All but DBL3X-S3 recombinant proteins bound to CSA expressed on Chinese hamster ovary (CHO)-K1 cells but not to CHO-pgsA745 cells, which are CSA negative as determined by flow cytometry. All but DBL3X-S3 bound to CSA on chondroitin sulfate proteoglycan (CSPG) as determined by surface plasmon resonance (SPR) analysis. Purified IgG from rats and rabbits immunized with these four recombinant proteins bound homologous and some heterologous parasite-infected erythrocytes (IE). Using a novel flow cytometry inhibition-of-binding assay (flow-IBA), antibodies against DBL3X-S3 inhibited 35% and 45% of IE binding to CSA on CHO-K1 cells compared to results for soluble CSA (sCSA) and purified multigravida (MG) IgG, respectively, from areas in Tanzania to which malaria is endemic. Antibodies generated against the other domains provided little or no inhibition of IE binding to CSA on CHO-K1 cells as determined by the flow cytometry inhibition-of-binding assay. These results demonstrate for the first time the ability to identify antibodies to VAR2CSA DBL domains and subdomains capable of inhibiting VAR2CSA parasite-IE binding to CSA by flow cytometry. The flow cytometry inhibition-of-binding assay was robust and provided an accurate, reproducible, and reliable means to identify blocking of IE binding to CSA and promises to be significant in the development of a vaccine to protect pregnant women.

scholarly journals Cross-Reactive Surface Epitopes on Chondroitin Sulfate A-Adherent Plasmodium falciparum-Infected Erythrocytes Are Associated with Transcription of var2csa

2005 ◽  
Vol 73 (5) ◽  
pp. 2848-2856 ◽  
Author(s):  
Salenna R. Elliott ◽  
Michael F. Duffy ◽  
Timothy J. Byrne ◽  
James G. Beeson ◽  
Emily J. Mann ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Chondroitin Sulfate ◽  
Erythrocyte Membrane ◽  
Cell Sorting ◽  
Rabbit Antiserum ◽  
Fluorescence Activated Cell Sorting ◽  
Parasite Protein ◽  
Chondroitin Sulfate A ◽  
In Pregnancy

ABSTRACT Malaria in pregnancy is associated with placental accumulation of Plasmodium falciparum-infected erythrocytes (IE) that adhere to chondroitin sulfate A (CSA). Adhesion is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1), a variant parasite protein expressed on the surface of IE and encoded by var genes. Rabbit antiserum was generated against the CSA-adherent P. falciparum line CS2, in which the dominant var transcribed is var2csa, a relatively conserved var gene that has been associated with CSA adhesion. Anti-CS2 recognized genetically distinct CSA-adherent P. falciparum lines but not CD36-adherent parent lines. Reactivity with anti-CS2 correlated with the level of adhesion to CSA. Fluorescence-activated cell sorting according to binding of anti-CS2 showed reactivity was associated with CSA adhesion and transcription of var2csa. These data are consistent with the hypothesis that var2csa encodes a PfEMP1 expressed on the surface of IE, which mediates adhesion to CSA and is relatively conserved between genetically distinct strains of P. falciparum.

Identifying targets of protective antibodies against severe malaria in Papua, Indonesia using locally expressed domains of Plasmodium falciparum Erythrocyte Membrane Protein 1.

2021 ◽  
Author(s):  
Janavi S Rambhatla ◽  
Gerry Q Tonkin-Hill ◽  
Eizo Takashima ◽  
Takafumi Tsuboi ◽  
Rintis Noviyanti ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Severe Malaria ◽  
Erythrocyte Membrane ◽  
Uncomplicated Malaria ◽  
Igg Antibodies ◽  
Erythrocyte Membrane Protein ◽  
African Children ◽  
Genes Encoding ◽  
Malaria Severity

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a diverse family of multi-domain proteins expressed on the surface of malaria-infected erythrocytes, is an important target of protective immunity against malaria. Our group recently studied transcription of the var genes encoding PfEMP1 in individuals from Papua, Indonesia with severe or uncomplicated malaria. We cloned and expressed domains from 32 PfEMP1s including 22 that were upregulated in severe malaria and 10 that were upregulated in uncomplicated malaria, using a wheat germ cell-free expression system. We used Luminex technology to measure IgG antibodies to these 32 domains and control proteins in 63 individuals (11 children). At presentation to hospital, levels of antibodies to PfEMP1 domains were either higher in uncomplicated malaria or were not significantly different between groups. Using principal components analysis, antibodies to three of 32 domains were highly discriminatory between groups. These included two domains upregulated in severe malaria, a DBLβ13 domain and a CIDRα1.6 domain (which has been previously implicated in severe malaria pathogenesis), and a DBLδ domain that was upregulated in uncomplicated malaria. Antibody to control non-PfEMP1 antigens did not differ with disease severity. Antibodies to PfEMP1 domains differ with malaria severity. Lack of antibodies to locally expressed PfEMP1 types, including both domains previously associated with severe malaria and newly identified targets, may in part explain malaria severity in Papuan adults. Importance Severe Plasmodium falciparum malaria kills many African children, and lack of antibody immunity predisposes to severe disease. A critical antibody target is the P. falciparum erythrocyte membrane 1 (PfEMP1) family of multidomain proteins, which are expressed on the infected erythrocyte surface and mediate parasite sequestration in deep organs. We previously identified var genes encoding PfEMP1 that were differentially expressed between severe and uncomplicated malaria in Papua, Indonesia. Here, we have expressed domains from 32 of these PfEMP1s and measured IgG antibody responses to them in Papuan adults and children. Using Principal Component Analysis, IgG antibodies to three domains distinguished between severe and uncomplicated malaria and were higher in uncomplicated malaria. Domains included CIDRα1.6, implicated in severe malaria; a DBLβ13 domain; and a DBLδ domain of unknown function. Immunity to locally relevant PfEMP1 domains may protect from severe malaria. Targets of immunity show important overlap between Asian adults and African children.

scholarly journals DNA secondary structures are associated with recombination in major Plasmodium falciparum variable surface antigen gene families

2013 ◽  
Vol 42 (4) ◽  
pp. 2270-2281 ◽  
Author(s):  
Adam F. Sander ◽  
Thomas Lavstsen ◽  
Thomas S. Rask ◽  
Michael Lisby ◽  
Ali Salanti ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Erythrocyte Membrane ◽  
Gene Families ◽  
Secondary Structures ◽  
Erythrocyte Membrane Protein ◽  
Sexual Stages ◽  
Dna Secondary Structures ◽  
Parasitic Pathogens ◽  
Falciparum Erythrocyte Membrane Protein

Abstract Many bacterial, viral and parasitic pathogens undergo antigenic variation to counter host immune defense mechanisms. In Plasmodium falciparum, the most lethal of human malaria parasites, switching of var gene expression results in alternating expression of the adhesion proteins of the Plasmodium falciparum-erythrocyte membrane protein 1 class on the infected erythrocyte surface. Recombination clearly generates var diversity, but the nature and control of the genetic exchanges involved remain unclear. By experimental and bioinformatic identification of recombination events and genome-wide recombination hotspots in var genes, we show that during the parasite’s sexual stages, ectopic recombination between isogenous var paralogs occurs near low folding free energy DNA 50-mers and that these sequences are heavily concentrated at the boundaries of regions encoding individual Plasmodium falciparum-erythrocyte membrane protein 1 structural domains. The recombinogenic potential of these 50-mers is not parasite-specific because these sequences also induce recombination when transferred to the yeast Saccharomyces cerevisiae. Genetic cross data suggest that DNA secondary structures (DSS) act as inducers of recombination during DNA replication in P. falciparum sexual stages, and that these DSS-regulated genetic exchanges generate functional and diverse P. falciparum adhesion antigens. DSS-induced recombination may represent a common mechanism for optimizing the evolvability of virulence gene families in pathogens.

scholarly journals Identification of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) as the Rosetting Ligand of the Malaria Parasite P. falciparum

1998 ◽  
Vol 187 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Qijun Chen ◽  
Antonio Barragan ◽  
Victor Fernandez ◽  
Annika Sundström ◽  
Martha Schlichtherle ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Heparan Sulfate ◽  
Erythrocyte Membrane ◽  
Plasmodium Falciparum Malaria ◽  
Glutathione S Transferase ◽  
Binding Motifs ◽  
Erythrocyte Membrane Protein ◽  
Adhesive Interactions ◽  
Falciparum Erythrocyte Membrane Protein

Severe Plasmodium falciparum malaria is characterized by excessive sequestration of infected and uninfected erythrocytes in the microvasculature of the affected organ. Rosetting, the adhesion of P. falciparum–infected erythrocytes to uninfected erythrocytes is a virulent parasite phenotype associated with the occurrence of severe malaria. Here we report on the identification by single-cell reverse transcriptase PCR and cDNA cloning of the adhesive ligand P. falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting PfEMP1 contains clusters of glycosaminoglycan-binding motifs. A recombinant fusion protein (Duffy binding-like 1–glutathione S transferase; Duffy binding-like-1–GST) was found to adhere directly to normal erythrocytes, disrupt naturally formed rosettes, block rosette reformation, and bind to a heparin-Sepharose matrix. The adhesive interactions could be inhibited with heparan sulfate or enzymes that remove heparan sulfate from the cell surface whereas other enzymes or similar glycosaminoglycans of a like negative charge did not affect the binding. PfEMP1 is suggested to be the rosetting ligand and heparan sulfate, or a heparan sulfate–like molecule, the receptor both for PfEMP1 binding and naturally formed erythrocyte rosettes.

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