Antimalarial Activity of Cupredoxins

The discovery of effective new antimalarial agents is urgently needed. One of the most frequently studied molecules anchored to the parasite surface is the merozoite surface protein-1 (MSP1). At red blood cell invasion MSP1 is proteolytically processed, and the 19-kDa C-terminal fragment (MSP119) remains on the surface and is taken into the red blood cell, where it is transferred to the food vacuole and persists until the end of the intracellular cycle. Because a number of specific antibodies inhibit erythrocyte invasion and parasite growth, MSP119 is therefore a promising target against malaria. Given the structural homology of cupredoxins with the Fab domain of monoclonal antibodies, an approach combining NMR and isothermal titration calorimetry (ITC) measurements with docking calculations based on BiGGER is employed on MSP119-cupredoxin complexes. Among the cupredoxins tested, rusticyanin forms a well defined complex with MSP119 at a site that overlaps with the surface recognized by the inhibitory antibodies. The addition of holo-rusticyanin to infected cells results in parasitemia inhibition, but negligible effects on parasite growth can be observed for apo-rusticyanin and other proteins of the cupredoxin family. These findings point to rusticyanin as an excellent therapeutic tool for malaria treatment and provide valuable information for drug design.

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The malaria parasite sheddase SUB2 governs host red blood cell membrane sealing at invasion

10.1101/2020.07.15.205732 ◽

2020 ◽

Author(s):

Christine R Collins ◽

Fiona Hackett ◽

Steven A Howell ◽

Ambrosius P Snijders ◽

Matthew RG Russell ◽

...

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Malaria Parasite ◽

Parasitophorous Vacuole ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Surface Proteins ◽

List Type ◽

Rbc Membrane ◽

Membrane Sealing

AbstractRed blood cell (RBC) invasion by malaria merozoites involves formation of a parasitophorous vacuole into which the parasite moves. The vacuole membrane seals and pinches off behind the parasite through an unknown mechanism, enclosing the parasite within the RBC. During invasion, several parasite surface proteins are shed by a membrane-bound protease called SUB2. Here we show that genetic depletion of SUB2 abolishes shedding of a range of parasite proteins, identifying previously unrecognized SUB2 substrates. Interaction of SUB2-null merozoites with RBCs leads to either abortive invasion with rapid RBC lysis, or successful entry but developmental arrest. Selective failure to shed the most abundant SUB2 substrate, MSP1, reduces intracellular replication, whilst conditional ablation of the substrate AMA1 produces host RBC lysis. We conclude that SUB2 activity is critical for host RBC membrane sealing following parasite internalisation and for correct functioning of merozoite surface proteins.Key highlightsMany malaria parasite surface proteins are shed by SUB2 during RBC invasionSUB2-null merozoites either induce rapid host RBC lysis, or invade then dieMerozoite surface protein shedding is crucial for host RBC membrane sealing

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Distinct Th1- and Th2-Type Prenatal Cytokine Responses to Plasmodium falciparum Erythrocyte Invasion Ligands

Infection and Immunity ◽

10.1128/iai.73.6.3462-3470.2005 ◽

2005 ◽

Vol 73 (6) ◽

pp. 3462-3470 ◽

Cited By ~ 70

Author(s):

Indu Malhotra ◽

Peter Mungai ◽

Eric Muchiri ◽

John Ouma ◽

Shobhona Sharma ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Cord Blood ◽

Interleukin 2 ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Cd8 Cells ◽

Erythrocyte Invasion ◽

Cytokine Responses ◽

Th1 And Th2 Responses ◽

Th1 And Th2

ABSTRACT Prenatal immunity to Plasmodium falciparum merozoite proteins involved in erythrocyte invasion may contribute to the partial protection against malaria that is acquired during infancy in areas of stable malaria transmission. We examined newborn and maternal cytokine and antibody responses to merozoite surface protein-1 (MSP-1), ribosomal phosphoprotein P0 (PfP0), and region II of erythrocyte binding antigen-175 (EBA-175) in infant-mother pairs in Kenya. Overall, 82 of 167 (50%), 106 of 176 (60%), and 38 of 84 (45%) cord blood lymphocytes (CBL) from newborns produced one or more cytokines in response to MSP-1, PfP0, and EBA-175, respectively. Newborns of primigravid and/or malaria-infected women were more likely to have antigen-responsive CBL than were newborns of multigravid and/or uninfected women at delivery. Newborn cytokine responses did not match those of their mothers and fell into three distinct categories, Th1 (21 of 55 CBL donors produced only gamma interferon and/or interleukin 2 [IL-2]), Th2 (21 of 55 produced only IL-5 and/or IL-13), and mixed Th1/Th2 (13 of 55). Newborns produced more IL-10 than adults. High and low levels of cord blood IL-12 p70 production induced by anti-CD40 activation were associated with malaria-specific Th1 and Th2 responses, respectively. Antigen-responsive CBL in some newborns were detected only after depletion of IL-10-secreting CD8 cells with enrichment for CD4 cells. These data indicate that prenatal sensitization to blood-stage Plasmodium falciparum occurs frequently in areas where malaria is holoendemic. Modulation of this immunity, possibly by maternal parity and malaria, may affect the acquisition of protective immunity against malaria during infancy.

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Accounting for red blood cell accessibility reveals distinct invasion strategies inPlasmodium falciparumstrains

10.1101/626044 ◽

2019 ◽

Author(s):

Francisco Cai ◽

Tiffany M. DeSimone ◽

Elsa Hansen ◽

Cameron V. Jennings ◽

Amy K. Bei ◽

...

Keyword(s):

Blood Cell ◽

Red Blood Cells ◽

Red Blood Cell ◽

Blood Cells ◽

Cell Structure ◽

Clinical Manifestations ◽

Parasite Growth ◽

Invasion Pathways ◽

Invasion Rate

AbstractThe growth of the malaria parasitePlasmodium falciparumin human blood causes all clinical manifestations of malaria, a process that begins with the invasion of red blood cells. Parasites enter red blood cells using distinct pairs of parasite ligands and host receptors that define particular invasion pathways. Parasite strains have the capacity to switch between invasion pathways. This flexibility is thought to facilitate immune evasion against particular parasite ligands, but may also reflect the fact that red blood cell surfaces are dynamic and composed of heterogeneous invasion targets. Different host genetic backgrounds affecting red blood cell structure have long been recognized to impact parasite growthin vivo, but even within a host, red blood cells undergo dramatic changes in morphology and receptor density as they age. The consequences of these heterogeneities for parasite growthin vivoremain unclear. Here, we measured the ability of laboratory strains ofP. falciparumrelying on distinct invasion pathways to enter red blood cells of different ages. We estimated invasion efficiency while accounting for the fact that even if the red blood cells display the appropriate receptors, not all are physically accessible to invading parasites. This approach revealed a tradeoff made by parasites between the fraction of susceptible cells and their invasion rate into them. We were able to distinguish between “specialist” strains exhibiting high invasion rate in fewer cells versus “generalist” strains invading less efficiently into a larger fraction of cells. We developed a mathematical model to predict that infection with a generalist strain would lead to higher peak parasitemiasin vivowhen compared with a specialist strain with similar overall proliferation rate. Thus, the heterogeneous ecology of red blood cells may play a key role in determining the rate of parasite proliferation between different strains ofP. falciparum.

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Suramin and Suramin Analogues Inhibit Merozoite Surface Protein-1 Secondary Processing and Erythrocyte Invasion by the Malaria ParasitePlasmodium falciparum

Journal of Biological Chemistry ◽

10.1074/jbc.m306603200 ◽

2003 ◽

Vol 278 (48) ◽

pp. 47670-47677 ◽

Cited By ~ 45

Author(s):

Suzanne L. Fleck ◽

Berry Birdsall ◽

Jeffrey Babon ◽

Anton R. Dluzewski ◽

Stephen R. Martin ◽

...

Keyword(s):

Surface Protein ◽

Merozoite Surface Protein ◽

Secondary Processing ◽

Merozoite Surface Protein 1 ◽

Erythrocyte Invasion

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Inhibition of Erythrocyte Invasion and Plasmodium falciparum Merozoite Surface Protein 1 Processing by Human Immunoglobulin G1 (IgG1) and IgG3 Antibodies

Infection and Immunity ◽

10.1128/iai.00167-09 ◽

2009 ◽

Vol 77 (12) ◽

pp. 5659-5667 ◽

Cited By ~ 25

Author(s):

Maria Lazarou ◽

José A. Guevara Patiño ◽

Richard M. Jennings ◽

Richard S. McIntosh ◽

Jianguo Shi ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Dna Sequences ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Amino Acid Sequences ◽

Human Immunoglobulin ◽

Human Neutrophils ◽

Merozoite Surface Protein 1 ◽

Erythrocyte Invasion ◽

Carboxy Terminal

ABSTRACT Antigen-specific antibodies (Abs) to the 19-kDa carboxy-terminal region of Plasmodium falciparum merozoite surface protein 1 (MSP119) play an important role in protective immunity to malaria. Mouse monoclonal Abs (MAbs) 12.10 and 12.8 recognizing MSP119 can inhibit red cell invasion by interfering with MSP1 processing on the merozoite surface. We show here that this ability is dependent on the intact Ab since Fab and F(ab′)2 fragments derived from MAb 12.10, although capable of binding MSP1 with high affinity and competing with the intact antibody for binding to MSP1, were unable to inhibit erythrocyte invasion or MSP1 processing. The DNA sequences of the variable (V) regions of both MAbs 12.8 and 12.10 were obtained, and partial amino acid sequences of the same regions were confirmed by mass spectrometry. Human chimeric Abs constructed by using these sequences, which combine the original mouse V regions with human γ1 and γ3 constant regions, retain the ability to bind to both parasites and recombinant MSP119, and both chimeric human immunoglobulin G1s (IgG1s) were at least as good at inhibiting erythrocyte invasion as the parental murine MAbs 12.8 and 12.10. Furthermore, the human chimeric Abs of the IgG1 class (but not the corresponding human IgG3), induced significant NADPH-mediated oxidative bursts and degranulation from human neutrophils. These chimeric human Abs will enable investigators to examine the role of human Fcγ receptors in immunity to malaria using a transgenic parasite and mouse model and may prove useful in humans for neutralizing parasites as an adjunct to antimalarial drug therapy.

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Antibodies inhibit the protease-mediated processing of a malaria merozoite surface protein.

Journal of Experimental Medicine ◽

10.1084/jem.180.1.389 ◽

1994 ◽

Vol 180 (1) ◽

pp. 389-393 ◽

Cited By ~ 179

Author(s):

M J Blackman ◽

T J Scott-Finnigan ◽

S Shai ◽

A A Holder

Keyword(s):

Malaria Parasite ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Secondary Processing ◽

Erythrocyte Invasion ◽

Parasite Plasmodium ◽

Parasite Plasmodium Falciparum ◽

Protective Antibodies ◽

Epidermal Growth ◽

Membrane Bound

When merozoites of the malaria parasite Plasmodium falciparum are released from infected erythrocytes and invade new red cells, a component of a protein complex derived from the merozoite surface protein 1 (MSP-1) precursor undergoes a single proteolytic cleavage known as secondary processing. This releases the complex from the parasite surface, except for a small membrane-bound fragment consisting of two epidermal growth factor (EGF)-like domains, which is the only part of MSP-1 to be carried into invaded erythrocytes. We report that, a group of monoclonal antibodies specific for epitopes within the EGF-like domains, some interfere with secondary processing whereas others do not. Those that most effectively inhibit processing have previously been shown to prevent invasion. Other antibodies, some of which can block this inhibition, not only do not prevent invasion but are carried into the host cell bound to the merozoite surface. These observations unequivocally demonstrate that the binding of antibody to the COOH-terminal region of MSP-1 on the merozoite surface may not be sufficient to prevent erythrocyte invasion, and show that the interaction of different antibodies with adjacent epitopes within the EGF-like domains of MSP-1 can have distinct biochemical effects on the molecule. Inhibition of MSP-1 processing on merozoites may be a mechanism by which protective antibodies interrupt the asexual cycle of the malaria parasite.

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Marine organism sulfated polysaccharides exhibiting significant antimalarial activity and inhibition of red blood cell invasion by Plasmodium

Scientific Reports ◽

10.1038/srep24368 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 31

Author(s):

Joana Marques ◽

Eduardo Vilanova ◽

Paulo A. S. Mourão ◽

Xavier Fernàndez-Busquets

Keyword(s):

Blood Cell ◽

Cell Invasion ◽

Red Blood Cell ◽

Marine Organism ◽

Antimalarial Activity ◽

Sulfated Polysaccharides

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A single fragment of a malaria merozoite surface protein remains on the parasite during red cell invasion and is the target of invasion-inhibiting antibodies.

Journal of Experimental Medicine ◽

10.1084/jem.172.1.379 ◽

1990 ◽

Vol 172 (1) ◽

pp. 379-382 ◽

Cited By ~ 379

Author(s):

M J Blackman ◽

H G Heidrich ◽

S Donachie ◽

J S McBride ◽

A A Holder

Keyword(s):

Cell Invasion ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Red Cell ◽

Small Fragment ◽

Erythrocyte Invasion ◽

Single Fragment

A complex of polypeptides derived from a precursor is present on the surface of the malaria merozoite. During erythrocyte invasion only a small fragment from this complex is retained on the parasite surface and carried into the newly infected red cell. Antibodies to this fragment will interrupt invasion.

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