scholarly journals Deletion of the Plasmodium falciparum Merozoite Surface Protein 7 Gene Impairs Parasite Invasion of Erythrocytes

2008 ◽  
Vol 7 (12) ◽  
pp. 2123-2132 ◽  
Author(s):  
Madhusudan Kadekoppala ◽  
Rebecca A. O'Donnell ◽  
Munira Grainger ◽  
Brendan S. Crabb ◽  
Anthony A. Holder
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Interactions ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Significant Degree ◽  
Surface Proteins ◽  
Transcriptional Level ◽  
Parental Line ◽  
Parasite Line ◽  
Asexual Blood Stage

ABSTRACT Merozoite surface proteins have been implicated in the initial attachment to the host red blood cell membrane that begins the process of invasion, an important step in the life cycle of the malaria parasite. In Plasmodium falciparum, merozoite surface proteins include several glycosylphosphatidyl inositol-anchored proteins and peripheral proteins attached to the membrane through protein-protein interactions. The most abundant of these proteins is the merozoite surface protein 1 (MSP1) complex, encoded by at least three genes: msp1, msp6, and msp7. The msp7 gene is part of a six-member multigene family in Plasmodium falciparum. We have disrupted msp7 in the Plasmodium falciparum D10 parasite, as confirmed by Southern hybridization. Immunoblot and indirect immunofluorescence analyses confirmed the MSP7 null phenotype of D10ΔMSP7 parasites. The synthesis, distribution, and processing of MSP1 were not affected in this parasite line. The level of expression and cellular distribution of the proteins MSP1, MSP3, MSP6, MSP9, and SERA5 remained comparable to those for the parental line. Furthermore, no significant change in the expression of MSP7-related proteins, except for that of MSRP5, was detected at the transcriptional level. The lack of MSP7 was not lethal at the asexual blood stage, but it did impair invasion of erythrocytes by merozoites to a significant degree. Despite this reduction in efficiency, D10ΔMSP7 parasites did not show any obvious preference for alternate pathways of invasion.

scholarly journals A Common Cross-species Function for the Double Epidermal Growth Factor-like Modules of the Highly DivergentPlasmodiumSurface Proteins MSP-1 and MSP-8

2004 ◽  
Vol 279 (19) ◽  
pp. 20147-20153 ◽  
Author(s):  
Damien R. Drew ◽  
Rebecca A. O'Donnell ◽  
Brian J. Smith ◽  
Brendan S. Crabb
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Drug Targets ◽  
Point Mutations ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Parasite Line ◽  
Asexual Blood Stage ◽  
Epidermal Growth

An understanding of structural and functional constraints on the C-terminal double epidermal growth factor (EGF)-like modules of merozoite surface protein (MSP)-1 and related proteins is of importance to the development of these molecules as malaria vaccines and drug targets. Using allelic replacement, we show thatPlasmodium falciparumparasites can invade erythrocytes and grow efficiently in the absence of an MSP-1 protein with authentic MSP-1 EGF domains. In this mutant parasite line, the MSP-1 EGFs were replaced by the corresponding double EGF module fromP. bergheiMSP-8, the sequence of which shares only low identity with its MSP-1 counterpart. Hence, the C-terminal EGF domains of at least somePlasmodiumsurface proteins appear to perform the same function in asexual blood-stage development. Mapping the surface location of the few residues that are common to these functionally complementary EGF modules revealed the presence of a highly conserved pocket of potential functional significance. In contrast to MSP-8, an even more divergent double EGF module, that from the sexual stage protein PbS25, was not capable of complementing MSP-1 EGF function. More surprisingly, two chimeric double EGF modules comprising hybrids of the EGF domains fromP. falciparumandP. chabaudiMSP-1 were also not capable of replacing theP. falciparumMSP-1 EGF module. Together, these data suggest that although the MSP-1 EGFs can accommodate extensive sequence diversity, there appear to be constraints that may restrict the simple accumulation of point mutations in the face of immune pressure in the field.

scholarly journals Plasmodium falciparum Merozoite Surface Protein 6 Is a Dimorphic Antigen

2004 ◽  
Vol 72 (4) ◽  
pp. 2321-2328 ◽  
Author(s):  
J. Andrew Pearce ◽  
Tony Triglia ◽  
Anthony N. Hodder ◽  
David C. Jackson ◽  
Alan F. Cowman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Structures ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Parasite Line ◽  
Merozoite Surface Protein 1 ◽  
Erythrocyte Invasion ◽  
Falciparum Merozoite ◽  
Asexual Cycle

ABSTRACT Merozoite surface protein 1 (MSP1) is a highly polymorphic Plasmodium falciparum merozoite surface protein implicated in the invasion of human erythrocytes during the asexual cycle. It forms a complex with MSP6 and MSP7 on the merozoite surface, and this complex is released from the parasite around the time of erythrocyte invasion. MSP1 and many other merozoite surface proteins contain dimorphic elements in their protein structures, and here we show that MSP6 is also dimorphic. The sequences of eight MSP6 genes indicate that the alleles of each dimorphic form of MSP6 are highly conserved. The smaller 3D7-type MSP6 alleles are detected in parasites from all malarious regions of the world, whereas K1-type MSP6 alleles have only been detected in parasites from mainland Southeast Asia. Cleavage of MSP6, which produces the p36 fragment in 3D7-type MSP6 and associates with MSP1, also occurs in K1-type MSP6 but at a different site in the protein. Anti-3D7 MSP6 antibodies weakly inhibited erythrocyte invasion by homologous 3D7 merozoites but did not inhibit a parasite line expressing the K1-type MSP6 allele. Antibodies from hyperimmune individuals affinity purified on an MSP3 peptide cross-reacted with MSP6; therefore, MSP6 may also be a target of antibody-dependent cellular inhibition.

scholarly journals Systematic Genetic Analysis of the Plasmodium falciparum MSP7-Like Family Reveals Differences in Protein Expression, Location, and Importance in Asexual Growth of the Blood-Stage Parasite

2010 ◽  
Vol 9 (7) ◽  
pp. 1064-1074 ◽  
Author(s):  
Madhusudan Kadekoppala ◽  
Solabomi A. Ogun ◽  
Steven Howell ◽  
Ruwani S. Gunaratne ◽  
Anthony A. Holder
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Expression ◽  
Surface Protein ◽  
Gene Families ◽  
Merozoite Surface Protein ◽  
Blood Stage ◽  
Asexual Blood Stage ◽  
Content Type ◽  
Specific Proteins ◽  
Proteolytic Cleavages

ABSTRACT Proteins located on Plasmodium falciparum merozoites, the invasive form of the parasite's asexual blood stage, are of considerable interest in vaccine research. Merozoite surface protein 7 (MSP7) forms a complex with MSP1 and is encoded by a member of a multigene family located on chromosome 13. The family codes for MSP7 and five MSP7-related proteins (MSRPs). In the present study, we have investigated the expression and the effect of msrp gene deletion at the asexual blood stage. In addition to msp7, msrp2, msrp3, and msrp5 are transcribed, and mRNA was easily detected by hybridization analysis, whereas mRNA for msrp1 and msrp4 could be detected only by reverse transcription (RT)-PCR. Notwithstanding evidence of transcription, antibodies to recombinant MSRPs failed to detect specific proteins, except for antibodies to MSRP2. Sequential proteolytic cleavages of MSRP2 resulted in 28- and 25-kDa forms. However, MSRP2 was absent from merozoites; the 25-kDa MSRP2 protein (MSRP225) was soluble and secreted upon merozoite egress. The msrp genes were deleted by targeted disruption in the 3D7 line, leading to ablation of full-length transcripts. MSRP deletion mutants had no detectable phenotype, with growth and invasion characteristics comparable to those of the parental parasite; only the deletion of MSP7 led to a detectable growth phenotype. Thus, within this family some of the genes are transcribed at a significant level in asexual blood stages, but the corresponding proteins may or may not be detectable. Interactions of the expressed proteins with the merozoite also differ. These results highlight the potential for unexpected differences of protein expression levels within gene families.

scholarly journals Factors Associated with Immunoglobulin G Subclass Polarization in Naturally Acquired Antibodies to Plasmodium falciparum Merozoite Surface Proteins: a Cross-Sectional Survey in Brazilian Amazonia

2006 ◽  
Vol 13 (7) ◽  
pp. 810-813 ◽  
Author(s):  
Kézia K. G. Scopel ◽  
Cor J. F. Fontes ◽  
Marcelo U. Ferreira ◽  
Érika M. Braga
Keyword(s):  
Plasmodium Falciparum ◽  
Immunoglobulin G ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Falciparum Merozoite ◽  
Immunoglobulin G Subclass ◽  
Current Exposure

ABSTRACT We investigated immunoglobulin G (IgG) subclass antibody responses to Plasmodium falciparum merozoite surface protein 1 (MSP-1) and MSP-2 in 112 malaria-exposed subjects in Brazil. IgG3 polarization was primarily epitope driven, being little affected by cumulative or current exposure to malaria and not affected by a subject's age and Fcγ receptor IIA genotype.

scholarly journals Antigenic Characterization of an Intrinsically Unstructured Protein, Plasmodium falciparum Merozoite Surface Protein 2

2012 ◽  
Vol 80 (12) ◽  
pp. 4177-4185 ◽  
Author(s):  
Christopher G. Adda ◽  
Christopher A. MacRaild ◽  
Linda Reiling ◽  
Kaye Wycherley ◽  
Michelle J. Boyle ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Surface Protein ◽  
Variable Region ◽  
Intrinsic Property ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Structural Basis ◽  
Content Type ◽  
Intrinsically Unstructured Protein ◽  
Unstructured Protein

ABSTRACTMerozoite surface protein 2 (MSP2) is an abundant glycosylphosphatidylinositol (GPI)-anchored protein ofPlasmodium falciparum, which is a potential component of a malaria vaccine. As all forms of MSP2 can be categorized into two allelic families, a vaccine containing two representative forms of MSP2 may overcome the problem of diversity in this highly polymorphic protein. Monomeric recombinant MSP2 is an intrinsically unstructured protein, but its conformational properties on the merozoite surface are unknown. This question is addressed here by analyzing the 3D7 and FC27 forms of recombinant and parasite MSP2 using a panel of monoclonal antibodies raised against recombinant MSP2. The epitopes of all antibodies, mapped using both a peptide array and by nuclear magnetic resonance (NMR) spectroscopy on full-length recombinant MSP2, were shown to be linear. The antibodies revealed antigenic differences, which indicate that the conserved N- and C-terminal regions, but not the central variable region, are less accessible in the parasite antigen. This appears to be an intrinsic property of parasite MSP2 and is not dependent on interactions with other merozoite surface proteins as the loss of some conserved-region epitopes seen using the immunofluorescence assay (IFA) on parasite smears was also seen on Western blot analyses of parasite lysates. Further studies of the structural basis of these antigenic differences are required in order to optimize recombinant MSP2 constructs being evaluated as potential vaccine components.

Interactions with heparin-like molecules during erythrocyte invasion by Plasmodium falciparum merozoites

Blood ◽  
2010 ◽  
Vol 115 (22) ◽  
pp. 4559-4568 ◽  
Author(s):  
Michelle J. Boyle ◽  
Jack S. Richards ◽  
Paul R. Gilson ◽  
Wengang Chai ◽  
James G. Beeson
Keyword(s):  
Plasmodium Falciparum ◽  
Current Knowledge ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Invasion Pathways ◽  
Erythrocyte Invasion ◽  
Ligand Interactions ◽  
Processed Form ◽  
Multiple Receptor

AbstractDuring erythrocyte invasion, Plasmodium falciparum merozoites use multiple receptor-ligand interactions in a series of coordinated events, but current knowledge of these interactions is limited. Using real-time imaging of invasion, we established that heparin-like molecules block early, and essential, events in erythrocyte invasion by merozoites. All P falciparum isolates tested, and parasites using different invasion pathways were inhibited to comparable levels. Furthermore, it was not possible to select for heparin-resistant parasites. Heparin-like molecules occur naturally on the surface of human erythrocytes, where they may act as receptors for binding of merozoite surface proteins. Consistent with this, we demonstrated that MSP1-42, a processed form of merozoite surface protein 1 (MSP1) involved in invasion, bound heparin in a specific manner; furthermore, binding was observed with the secondary processing fragment MSP1-33, but not MSP1-19. We defined key structural requirements of heparin-like molecules for invasion inhibition and interactions with MSP1-42. Optimal activity required a degree of sulfation more than or equal to 2, disulfation of the N-acetylglucosamine or hexuronic acid residue, and a minimum chain length of 6 monosaccharides. These findings have significant implications for understanding P falciparum invasion of erythrocytes and the development of novel therapeutics and vaccines.

Disruption of Plasmodium berghei merozoite surface protein 7 gene modulates parasite growth in vivo

Blood ◽  
2005 ◽  
Vol 105 (1) ◽  
pp. 394-396 ◽  
Author(s):  
Rita Tewari ◽  
Solabomi A. Ogun ◽  
Ruwani S. Gunaratne ◽  
Andrea Crisanti ◽  
Anthony A. Holder
Keyword(s):  
Plasmodium Falciparum ◽  
Gene Family ◽  
Plasmodium Berghei ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Plasmodium Yoelii ◽  
Parasite Growth ◽  
Surface Proteins ◽  
Rate Of Increase

Abstract Merozoite invasion of red blood cells is crucial to the development of the parasite that causes malaria. Merozoite surface proteins (MSPs) mediate the first interaction between parasite and erythrocyte. In Plasmodium falciparum, they include a complex of products from at least 3 genes (msp1, msp6, and msp7), one of which, msp7, is part of a gene family containing 3 and 6 adjacent members in Plasmodium yoelii and Plasmodium falciparum, respectively. We have identified and disrupted msp7 in the Plasmodium berghei gene family. The protein is expressed in schizonts and colocalizes with MSP1. The synthesis and processing of MSP1 was unaffected in the parasite with the disrupted gene (MSP7ko). Disruption of msp7 was not lethal but affected blood-stage parasite growth. MSP7ko parasites initially grew more slowly than wild-type parasites. However, when reticulocytes were prevalent, the rate of increase in parasitemia was similar, suggesting that MSP7ko parasites prefer to invade and grow within reticulocytes. (Blood. 2005;105:394-396)

scholarly journals Expression of Merozoite Surface Protein Markers by Plasmodium falciparum-Infected Erythrocytes in Peripheral Blood and Tissues of Children with Fatal Malaria

2006 ◽  
Vol 75 (2) ◽  
pp. 643-652 ◽  
Author(s):  
Carlota Dobaño ◽  
Stephen J. Rogerson ◽  
Terrie E. Taylor ◽  
Jana S. McBride ◽  
Malcolm E. Molyneux
Keyword(s):  
Plasmodium Falciparum ◽  
Cerebral Malaria ◽  
Peripheral Blood ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Surface Proteins ◽  
Pathological Feature ◽  
Protein Markers ◽  
The Brain ◽  
Different Tissues

ABSTRACT Sequestration of Plasmodium falciparum-infected erythrocytes is a pathological feature of fatal cerebral malaria. P. falciparum is genetically diverse among, and often within, patients. Preferential sequestration of certain genotypes might be important in pathogenesis. We compared circulating parasites with parasites sequestered in the brain, spleen, liver, and lung in the same Malawian children with fatal malaria, classifying serotypes using antibodies to merozoite surface proteins 1 and 2 and immunofluorescence in order to differentiate parasites and to quantify the proportions of each serotype. We found (i) similar distributions of various serotypes in different tissues and (ii) concordance between parasite serotypes in peripheral blood and parasite serotypes in tissues. No serotypes predominated in the brain in cerebral malaria, and parasites belonging to a single serotype did not cluster within individual vessels or within single tissues. These findings do not support the hypothesis that cerebral malaria is caused by cerebral sequestration of certain virulent types.

scholarly journals A screen for Plasmodium falciparum sporozoite surface protein binding to human hepatocyte surface receptors identifies novel host-pathogen interactions

2020 ◽  
Author(s):  
Rameswara Reddy Segireddy ◽  
Kirsten Dundas ◽  
Julia Knoeckel ◽  
Francis Galaway ◽  
Laura Wood ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Recombinant Proteins ◽  
Protein Interactions ◽  
Surface Protein ◽  
Human Hepatocyte ◽  
Surface Proteins ◽  
Protein Protein Interactions ◽  
Screening Assay ◽  
Host Pathogen ◽  
Pathogen Protein

AbstractSporozoite invasion of hepatocytes is a necessary step prior to development of malaria, with similarities, at the cellular level, to merozoite invasion of erythrocytes. In the case of the malaria blood-stage, efforts to identify host-pathogen protein-protein interactions have yielded important insights including vaccine candidates. In the case of sporozoite-hepatocyte invasion, the host-pathogen protein-protein interactions involved are poorly understood. Here, we performed a systematic screen to identify such interactions. We substantially extended previous Plasmodium falciparum and human surface protein ectodomain libraries, creating new libraries containing 88 P. falciparum sporozoite protein coding sequences and 182 sequences encoding human hepatocyte surface proteins. Having expressed recombinant proteins from these sequences, we used a plate-based assay capable of detecting low affinity interactions between recombinant proteins, modified for enhanced throughput, to screen the proteins for interactions. We were able to test 7540 sporozoite-hepatocyte protein pairs under conditions likely to be sensitive for interaction. We report and characterise an interaction between human fibroblast growth factor receptor 4 (FGFR4) and the P. falciparum protein Pf34, and describe an additional interaction between human low-density lipoprotein receptor (LDLR) and the P. falciparum protein PIESP15. Strategies to inhibit these interactions may have value in malaria prevention, and the modified interaction screening assay and protein expression libraries we report may be of wider value to the community.

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