scholarly journals Antibodies to Variant Antigens on the Surfaces of Infected Erythrocytes Are Associated with Protection from Malaria in Ghanaian Children

2001 ◽  
Vol 69 (6) ◽  
pp. 3713-3718 ◽  
Author(s):  
Daniel Dodoo ◽  
Trine Staalsoe ◽  
Haider Giha ◽  
Jørgen A. L. Kurtzhals ◽  
Bartholomew D. Akanmori ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Immunoglobulin G ◽  
Clinical Malaria ◽  
Enzyme Linked Immunosorbent Assay ◽  
Parasite Isolate ◽  
Variant Antigen ◽  
Effect Of Age

ABSTRACT Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a variant antigen expressed on the surface of infected erythrocytes. Each parasite genome contains about 40 PfEMP1 genes, but only 1 PfEMP1 gene is expressed at a given time. PfEMP1 serves as a parasite-sequestering ligand to endothelial cells and enables the parasites to avoid splenic passage. PfEMP1 antibodies may protect from disease by inhibiting sequestration, thus facilitating the destruction of infected erythrocytes in the spleen. In this study, we have measured antibodies in Ghanaian children to a conserved region of PfEMP1 by enzyme-linked immunosorbent assay and antibodies to variant molecules on erythrocytes infected with field isolates of P. falciparum by flow cytometry. Based on close clinical monitoring, the children were grouped into those who did (susceptible) and those who did not (protected) have malaria during the season. The prevalences of antibodies to both the conserved PfEMP1 peptide and the variant epitopes were greater than 50%, and the levels of immunoglobulin G (IgG) correlated with age. The levels of antibodies to both the conserved peptide and the variant epitopes were higher in protected than in susceptible children. After correcting for the effect of age, the levels of IgG to variant antigens on a Sudanese and a Ghanaian parasite isolate remained significantly higher in protected than in susceptible children. Thus, the levels of IgG to variant antigens expressed on the surface of infected erythrocytes correlated with protection from clinical malaria. In contrast, the levels of IgG to a peptide derived from a conserved part of PfEMP1 did not correlate with protection from malaria.

scholarly journals Levels of Plasma Immunoglobulin G with Specificity against the Cysteine-Rich Interdomain Regions of a Semiconserved Plasmodium falciparum Erythrocyte Membrane Protein 1, VAR4, Predict Protection against Malarial Anemia and Febrile Episodes

2006 ◽  
Vol 74 (5) ◽  
pp. 2867-2875 ◽  
Author(s):  
John P. A. Lusingu ◽  
Anja T. R. Jensen ◽  
Lasse S. Vestergaard ◽  
Daniel T. Minja ◽  
Michael B. Dalgaard ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Erythrocyte Membrane ◽  
Immunoglobulin G ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Erythrocyte Membrane Protein ◽  
Igg Binding ◽  
Febrile Episodes

ABSTRACT Antibodies to variant surface antigen have been implicated as mediators of malaria immunity in studies measuring immunoglobulin G (IgG) binding to infected erythrocytes. Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is an important target for these antibodies, but no study has directly linked the presence of PfEMP1 antibodies in children to protection. We measured plasma IgG levels to the cysteine-rich interdomain region 1α (CIDR1α) of VAR4 (VAR4-CIDR1α), a member of a semiconserved PfEMP1 subfamily, by enzyme-linked immunosorbent assay in 561 Tanzanian individuals, who were monitored clinically for 7 months. The participants resided in Mkokola (a high-transmission village where malaria is holoendemic) or Kwamasimba (a moderate-transmission village). For comparison, plasma IgG levels to two merozoite surface protein 1 (MSP1) constructs, MSP1-19 and MSP1 block 2, and a control CIDR1 domain were measured. VAR4-CIDR1α antibodies were acquired at an earlier age in Mkokola than in Kwamasimba, but after the age of 10 years the levels were comparable in the two villages. After controlling for age and other covariates, the risk of having anemia at enrollment was reduced in VAR4-CIDR1α responders for Mkokola (adjusted odds ratio [AOR], 0.49; 95% confidence interval [CI], 0.29 to 0.88; P = 0.016) and Kwamasimba (AOR, 0.33; 95% CI, 0.16 to 0.68; P = 0.003) villages. The risk of developing malaria fever was reduced among individuals with a measurable VAR4-CIDR1α response from Mkokola village (AOR, 0.51; 95% CI, 0.29 to 0.89; P = 0.018) but not in Kwamasimba. Antibody levels to the MSP1 constructs and the control CIDR1α domain were not associated with morbidity protection. These data strengthen the concept of developing vaccines based on PfEMP1.

scholarly journals Immunoglobulin G Antibodies to Merozoite Surface Antigens Are Associated with Recovery from Chloroquine-Resistant Plasmodium falciparum in Gambian Children

2006 ◽  
Vol 74 (5) ◽  
pp. 2887-2893 ◽  
Author(s):  
Margaret Pinder ◽  
Colin J. Sutherland ◽  
Fatoumatta Sisay-Joof ◽  
Jamila Ismaili ◽  
Matthew B. B. McCall ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Immunoglobulin G ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Clinical Malaria ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plasma Samples ◽  
Apical Membrane Antigen 1 ◽  
Merozoite Antigens ◽  
Functional Immunity

ABSTRACT We examined the hypothesis that recovery from uncomplicated malaria in patients carrying drug-resistant Plasmodium falciparum is a measure of acquired functional immunity and may therefore be associated with humoral responses to candidate vaccine antigens. Gambian children with malaria were treated with chloroquine in 28-day trials, and recovery was defined primarily as the absence of severe clinical malaria at any time and absence of parasitemia with fever after 3 days. Plasma samples from these children were assayed by enzyme-linked immunosorbent assay for immunoglobulin G (IgG) to recombinant merozoite antigens: apical membrane antigen 1 (AMA-1) and the 19-kDa C-terminal region of merozoite surface protein 1 (MSP-119), including antigenic variants of MSP-119 with double and triple substitutions. Antigen-specific IgG was more frequent in children who recovered, particularly that for MSP-119 (age-adjusted odds ratios: 0.32 [95% confidence interval, 0.05, 1.87; P = 0.168] for AMA-1, 0.19 [0.03, 1.11; P = 0.019] for recombinant MSP-119, 0.24 [0.04, 1.31; P = 0.032] for the recombinant MSP-119 double variant, and 0.18 [0.03, 0.97; P = 0.013] for the triple variant). IgG titers to MSP-119 and to the triple variant were higher in plasma samples taken 7 days after chloroquine treatment from children who carried resistant parasites but recovered and remained parasite free. Moreover, in children who were parasitemic on day 14 or day 28, there was an age-independent relationship between parasite density and IgG to both MSP-119 and the triple variant (coefficients of −0.550 and −0.590 and P values of 0.002 and 0.001, respectively). The results validate the use of this approach to identify antigens that are associated with protection from malaria.

scholarly journals CD36 Peptides That Block Cytoadherence Define the CD36 Binding Region for Plasmodium falciparum-Infected Erythrocytes

Blood ◽  
1999 ◽  
Vol 94 (6) ◽  
pp. 2121-2127 ◽  
Author(s):  
Dror I. Baruch ◽  
Xin C. Ma ◽  
Brittan Pasloske ◽  
Russell J. Howard ◽  
Louis H. Miller
Keyword(s):  
Endothelial Cells ◽  
Plasmodium Falciparum ◽  
Scavenger Receptor ◽  
Intercellular Adhesion Molecule ◽  
Microvascular Endothelial Cells ◽  
Binding Region ◽  
Intercellular Adhesion Molecule 1 ◽  
Severe Pathology ◽  
Variant Antigen ◽  
Micromolar Range

Abstract Mature Plasmodium falciparum parasitized erythrocytes (PE) sequester from the circulation by adhering to microvascular endothelial cells. PE sequestration contributes directly to the virulence and severe pathology of falciparum malaria. The scavenger receptor, CD36, is a major host receptor for PE adherence. PE adhesion to CD36 is mediated by the malarial variant antigen, P. falciparumerythrocyte membrane protein 1 (PfEMP1), and particularly by its cysteine-rich interdomain region 1 (CIDR-1). Several peptides from the extended immunodominant domain of CD36 (residues 139-184), including CD36 139-155, CD36 145-171, CD36 146-164, and CD36 156-184 interfered with the CD36-PfEMP1 interaction. Each of these peptides affected binding at the low micromolar range in 2 independent assays. Two peptides, CD36 145-171 and CD36 156-184, specifically blocked PE adhesion to CD36 without affecting binding to the host receptor intercellular adhesion molecule-1 (ICAM-1). Moreover, an adhesion blocking peptide from the ICAM-1 sequence inhibits the PfEMP1–ICAM-1 interaction without affecting adhesion to CD36. These results confirm earlier observations that PfEMP1 is also a receptor for ICAM-1. Thus, the region 139-184 and particularly the 146-164 or the 145-171 regions of CD36 form the adhesion region for P. falciparum PE. Adherence blocking peptides from this region may be useful for modeling the PE/PfEMP1 interaction with CD36 and for development of potential anti-adhesion therapeutics.

Multiple Species of Endothelial Microparticles (EMP) Released from Different Membrane Protein Clustering Domains Exhibit Distinctive Phenotypes and Activities.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1802-1802 ◽  
Author(s):  
Wenche Jy ◽  
Joaquin J. Jimenez ◽  
Lucia M. Mauro ◽  
Carlos Bidot ◽  
Lawrence L. Horstman ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Endothelial Cells ◽  
Membrane Protein ◽  
Fluorescence Microscopy ◽  
Cell Interaction ◽  
Color Flow ◽  
Multiple Species ◽  
Normal Controls

Abstract INTRODUCTION: We have previously shown that EMP comprise multiple species of vesicles released from endothelial cells (EC) upon stimulation. However, the mechanism underlying EMP release is not clear, nor is their functional role. We postulated that EMP release is initiated by formation of discrete clusters of membrane proteins, each of which may release distinctive EMP characterized by the predominant protein in the cluster or raft. Therefore, each such subspecies may have distinctive activities in cell interaction or other function. In this study, we employed flow cytometry to investigate this postulated mechanism, and compared in vitro with in vivo findings. METHODS: EMP were prepared by incubating renal endothelial cells (EC) with 10 ng/mL of TNF for 24hr. Two-color flow cytometry was used to analyze the phenotypic composition of the resulting EMP, the markers used including CD31, CD62E, CD51, CD54, annexinV (AnV), tissue factor (TF), and lectin Ulex europaeus I (Ulex). Fluorescence microscopy was used to study membrane protein movement and clustering. RESULTS:(1) Phenotypic composition of EMP was evaluated in culture supernatants by flow cytometry, first by the number detected with each marker. Expressed in millions/mL, they were: by Ulex, 280; AnV, 52; CD54, 48; CD62E, 46; CD31, 34; TF, 36; and CD51, 8.(2) Two-color technique was used to establish the degree to which more than 1 marker (antigen) was present on the same EMP. It was found that only a small fraction (<5%) of CD54+ or CD62E+ EMP were also positive for CD31, and vice versa.(3) Cell interactions: Incubating the EMP mixture with neutrophils resulted in selective binding of CD54+ and CD62E+ EMP to the neutrophils and loss of 95% and 70% of free CD54+ and CD62E+ EMP, respectively, from the cell-free supernatants. EMP positive for the other markers showed little binding to leukocytes. These data confirm subspecies of EMP with little overlap of markers and differing affinity for leukocytes. (4) Fluorescence microscopy: Upon EC stimulation, a time-dependent movement of surface markers CD31 and CD54 resulted in their clustering to different locations prior to shedding of vesicles. Majority of vesicles were seen to shed from these clusters. This process may explain how EC can release multiple subspecies of EMP. (5a) In vivo: Levels of CD54+ EMP were always low or nearly undetectable in plasma from patients or normal controls. However, high levels of CD54+ EMP/leukocyte conjugates were found in several thrombotic and inflammatory disorders. This is consistent with in vitro findings. (5b) In vivo total MP: Study of plasma from 26 normal controls showed that MP measured by Ulex were about 3 to 4-fold higher than if measured by AnV. The majority of Ulex+ MP were negative for AnV. SUMMARY:Our data support the hypothesis that upon activation or apoptosis, EC developed multiple membrane protein clusters as a prelude to EMP release.EMP species released from these membrane clusters exhibit distinctive phenotypes and activities such as leukocyte binding.AnV has been widely used a marker for total MP, but this will miss MP not expressing AnV. We show that the lectin marker Ulex gives the highest counts of MP, in vitro and in vivo, suggesting that Ulex may be a better proxy than AnV for defining total MP.

Overlapping antigenic repertoires of variant antigens expressed on the surface of erythrocytes infected by Plasmodium falciparum

Parasitology ◽  
1999 ◽  
Vol 119 (1) ◽  
pp. 7-17 ◽  
Author(s):  
H. A. GIHA ◽  
T. STAALSOE ◽  
D. DODOO ◽  
I. M. ELHASSAN ◽  
C. ROPER ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Plasmodium Falciparum ◽  
Membrane Protein ◽  
Malaria Transmission ◽  
Erythrocyte Membrane ◽  
Clonal Variation ◽  
Single Infection ◽  
Erythrocyte Membrane Protein ◽  
Degree Of Overlap ◽  
Eastern Sudan

Antibodies against variable antigens expressed on the surface of Plasmodium falciparum-infected erythrocytes are believed to be important for protection against malaria. A target for these antibodies is the P. falciparum erythrocyte membrane protein 1, PfEMP1, which is encoded by around 50 var genes and undergoes clonal variation. Using agglutination and mixed agglutination tests and flow cytometry to analyse the recognition of variant antigens on parasitized erythrocytes by plasma antibodies from individuals living in Daraweesh in eastern Sudan, an area of seasonal and unstable malaria transmission, we show that these antibodies recognize different variant antigens expressed by parasites of different genotype. Comparing the levels and acquisition of antibody to variant antigens in pairs of parasite isolates expressing different variant types, there is a correlation between the acquisition of antibodies to some combinations of variant antigens but not to others. These results indicate that (1) a single infection will induce the production of antibodies recognizing several variants of surface-expressed antigens, (2) the repertoire of variable antigens expressed by different parasites is overlapping and the degree of overlap differs between isolates, and (3) the expression of at least some variant antigens is genetically linked.

scholarly journals Interferon-γ and Interleukin-10 Responses during Clinical Malaria Episodes in Infants Aged 0–2 Years Prenatally Exposed to Plasmodium falciparum: Tanzanian Birth Cohort

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Boniphace Sylvester ◽  
Dinah B. Gasarasi ◽  
Said Aboud ◽  
Donath Tarimo ◽  
Siriel Masawe ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Prenatal Exposure ◽  
Geometric Mean ◽  
Placental Malaria ◽  
Clinical Malaria ◽  
Interleukin 10 ◽  
Interferon Γ ◽  
Enzyme Linked Immunosorbent Assay ◽  
Prenatally Exposed ◽  
Malaria Episodes

Background. Infants born to mothers with placental malaria are prenatally exposed to Plasmodium falciparum antigens. However, the effect of that exposure to subsequent immune responses has not been fully elucidated. This study aimed at determining the effect of prenatal exposure to P. falciparum on Interleukin-10 and Interferon-γ responses during clinical malaria episodes in the first 24 months of life. Methods. This prospective cohort study involved 215 infants aged 0-2 years born to mothers with or without placental malaria. Enzyme-linked immunosorbent assay (ELISA) was used to determine levels of IL-10 and IFN-γ in infants and detect IgM in cord blood. Data were analyzed using SPSS version 20. Findings. Geometric mean for IFN-γ in exposed infants was 557.9 pg/ml (95% CI: 511.6-604.1) and in unexposed infants it was 634.4 pg/ml (95% CI: 618.2-668.5) (P=0.02). Mean IL-10 was 22.4 pg/ml (95% CI: 19.4-28.4) and 15.1 pg/ml (95%CI: 12.4-17.6), respectively (P=0.01). Conclusions. Prenatal exposure to P. falciparum antigens significantly affects IL-10 and IFN-γ responses during clinical malaria episodes in the first two years of life.

scholarly journals DNA Immunization with the Cysteine-Rich Interdomain Region 1 of the Plasmodium falciparum Variant Antigen Elicits Limited Cross-Reactive Antibody Responses

2003 ◽  
Vol 71 (8) ◽  
pp. 4536-4543 ◽  
Author(s):  
Dror I. Baruch ◽  
Benoit Gamain ◽  
Louis H. Miller
Keyword(s):  
Plasmodium Falciparum ◽  
Chinese Hamster ◽  
Antibody Responses ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dna Immunization ◽  
Naked Dna ◽  
Antibody Titers ◽  
Variant Antigen ◽  
Reactive Antibody ◽  
Antigenic Competition

ABSTRACT The variant surface antigens of Plasmodium falciparum are an important component of naturally acquired immunity and an important vaccine target. However, these proteins appear to elicit primarily variant-specific antibodies. We tested if naked DNA immunization can elicit more cross-reactive antibody responses and allow simultaneous immunization with several variant constructs. Mice immunized with plasmid DNA expressing variant cysteine-rich interdomain region 1 (CIDR1) domains of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) developed antibodies that were reactive to the corresponding PfEMP1s as measured by an enzyme-linked immunosorbent assay, flow cytometry, and agglutination of parasitized erythrocytes (PEs). We observed some cross-reactive immune responses; for example, sera from mice immunized with one domain agglutinated PEs of various lines and recognized heterologous domains expressed on the surface of Chinese hamster ovary (CHO) cells. We found no significant antigenic competition when animals were immunized with a mixture of plasmids or immunized sequentially with individual constructs. Moreover, mixed or sequential immunizations resulted in greater cross-reactive agglutination responses than immunization with a single domain. Recombinant protein (Sc y179) immunization after priming with DNA (prime-boost regimen) increased antibody titers to the homologous domain substantially but seemed to diminish the cross-reactive responses somewhat. The titer of agglutinating antibodies was previously shown to correlate with protection. Surprisingly, the agglutination titers of sera from DNA immunization were high, similar to those of pooled human hyperimmune sera. These sera also appeared to give limited low-titer variant transcending agglutination. Thus, DNA immunization appears to be a very useful tool for developing variant antigen vaccines.

scholarly journals Malaria Transmission and Naturally Acquired Immunity to PfEMP-1

1999 ◽  
Vol 67 (12) ◽  
pp. 6369-6374 ◽  
Author(s):  
Karen P. Piper ◽  
Rhian E. Hayward ◽  
Martin J. Cox ◽  
Karen P. Day
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Membrane Protein ◽  
Malaria Transmission ◽  
Papua New Guinea ◽  
Immunoglobulin G ◽  
Acquired Immunity ◽  
Life Cycle Stages ◽  
Immune Mediated ◽  
Transmission Stage

ABSTRACT Why there are so few gametocytes (the transmission stage of malaria) in the blood of humans infected with Plasmodiumspp. is intriguing. This may be due either to reproductive restraint by the parasite or to unidentified gametocyte-specific immune-mediated clearance mechanisms. We propose another mechanism, a cross-stage immunity to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP-1). This molecule is expressed on the surface of the erythrocyte infected with either trophozoite or early gametocyte parasites. Immunoglobulin G antibodies to PfEMP-1, expressed on both life cycle stages, were measured in residents from an area where malaria is endemic, Papua New Guinea. Anti-PfEMP-1 prevalence increased with age, mirroring the decline in both the prevalence and the density of asexual and transmission stages in erythrocytes. These data led us to propose that immunity to PfEMP-1 may influence malaria transmission by regulation of the production of gametocytes. This regulation may be achieved in two ways: (i) by controlling asexual proliferation and density and (ii) by affecting gametocyte maturation.

scholarly journals Cytophilic Immunoglobulin Responses to Plasmodium falciparum Glutamate-Rich Protein Are Correlated with Protection against Clinical Malaria in Dielmo, Senegal

2000 ◽  
Vol 68 (5) ◽  
pp. 2617-2620 ◽  
Author(s):  
Claude Oeuvray ◽  
Michael Theisen ◽  
Christophe Rogier ◽  
Jean-Francois Trape ◽  
Søren Jepsen ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protective Immunity ◽  
Clinical Malaria ◽  
Parasite Growth ◽  
Antibody Responses ◽  
Plasma Samples ◽  
Confounding Effect ◽  
Human Antibodies ◽  
Age Related ◽  
Effect Of Age

ABSTRACT The goal of this study was to analyze antibody responses toPlasmodium falciparum glutamate-rich protein (GLURP) using clinical data and plasma samples obtained from villagers of Dielmo, Senegal. This molecule was chosen because it is targeted by human antibodies which induce parasite growth inhibition in antibody-dependent cellular inhibition (ADCI) assays. The results showed a strong correlation between protection against malaria attacks and levels of immunoglobulin G2 (IgG2) and IgG3 against GLURP94–489 (R0) and IgG3 against GLURP705–1178 (R2) when corrected for the confounding effect of age-related exposure to malaria. Thus, GLURP may play a role in the induction of protective immunity against P. falciparum malaria.

scholarly journals Baculovirus-Expressed Constructs Induce Immunoglobulin G That Recognizes VAR2CSA on Plasmodium falciparum- Infected Erythrocytes

2006 ◽  
Vol 74 (7) ◽  
pp. 4357-4360 ◽  
Author(s):  
Lea Barfod ◽  
Morten A. Nielsen ◽  
Louise Turner ◽  
Madeleine Dahlbäck ◽  
Anja T. R. Jensen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Plasmodium Falciparum ◽  
Immunosorbent Assay ◽  
Immunoglobulin G ◽  
Insect Cell ◽  
Insect Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Specific Antisera ◽  
Specific Igg

ABSTRACT We raised specific antisera against recombinant VAR2CSA domains produced in Escherichia coli and in insect cells. All were reactive in enzyme-linked immunosorbent assay, but only insect cell-derived constructs induced immunoglobulin G (IgG) that was reactive with native VAR2CSA on the surface of infected erythrocytes. Our data show that five of the six VAR2CSA Duffy-binding-like domains are surface exposed and that induction of surface-reactive VAR2CSA-specific IgG depends critically upon antigen conformation. These findings have implications for the development of vaccines against pregnancy-associated Plasmodium falciparum malaria.

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