scholarly journals Biosynthesis and processing of a Plasmodium falciparum schizont antigen recognized by immune serum and a monoclonal antibody.

1982 ◽  
Vol 156 (5) ◽  
pp. 1528-1538 ◽  
Author(s):  
A A Holder ◽  
R R Freeman
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Protective Antigen ◽  
Peptide Mapping ◽  
Immune Serum ◽  
Lower Molecular Weight ◽  
Developmental Cycle ◽  
Stage Of Development

Stage-specific protein synthesis by the erythrocytic forms of the malaria parasite Plasmodium falciparum was investigated by pulse labeling synchronous parasite cultures with [35S]methionine at 6-h intervals during a complete 48-h developmental cycle. About 40 labeled parasite proteins could be immunoprecipitated with human immune serum, and most of these were associated with the schizont stage of development. In particular, one schizont protein was a 195,000-mol wt species against which a murine monoclonal antibody was produced. This monoclonal antibody, 89.1 reacted with the parasite membrane in schizonts and also with the surface of free merozoites in the indirect immunofluorescence test. In addition to the 195,000-mol wt protein, antibody 89.1 immunoprecipitated a series of lower-molecular weight polypeptides from extracts of labeled asynchronous P. falciparum parasite cultures. These were shown to be related to the 195,000-mol wt protein by peptide mapping. Pulse-chase labeling of synchronized cultures, and immunoprecipitation with antibody 89.1, showed that specific processing of the 195,000-mol wt polypeptide to the lower-molecular-weight products in concomitant with schizont maturation and merozoite release. It is suggested that this P. falciparum protein may be analogous to a similarly processed 230,000-mol wt protective antigen of the rodent malaria parasite, P. yoelii.

scholarly journals Surface antigens of malaria merozoites. A high molecular weight precursor is processed to an 83,000 mol wt form expressed on the surface of Plasmodium falciparum merozoites.

1983 ◽  
Vol 158 (5) ◽  
pp. 1647-1653 ◽  
Author(s):  
R R Freeman ◽  
A A Holder
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Surface Antigens ◽  
Immune Serum ◽  
Differential Centrifugation ◽  
Synchronous Cultures ◽  
Human Immune ◽  
High Yields ◽  
Major Surface

A technique was developed for obtaining high yields of naturally released Plasmodium falciparum merozoites from synchronous cultures of parasitized erythrocytes. The cultured erythrocytes were treated with trypsin to prevent reinvasion (6), and the released merozoites that accumulated extracellularly were harvested by differential centrifugation. The total biosynthetically labeled proteins of schizonts and merozoites, and those immunoprecipitated by human immune serum were analyzed and compared. The surface antigens of free merozoites, labeled by lactoperoxidase-catalyzed iodination, were also described. A monoclonal antibody, specific for a 195,000 mol wt schizont protein, and processing fragments derived from it (3) were used in immunoprecipitation and Western transfer analyses to determine which of the processing fragments are associated with merozoites and which of them are located on the merozoite surface. It was found that processing of the 195,000 mol wt precursor down to an 83,000 mol wt fragment is complete in free merozoites, and that this fragment is expressed as one of the major surface antigens of P. falciparum merozoites.

Characterization of a high molecular weight protective antigen ofPlasmodium yoelli

Parasitology ◽  
1984 ◽  
Vol 88 (2) ◽  
pp. 211-219 ◽  
Author(s):  
A. A. Holder ◽  
R. R. Freeman
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
Specific Antibody ◽  
Protective Antigen ◽  
Peptide Mapping ◽  
Plasmodium Yoelii ◽  
Lower Molecular Weight ◽  
Large Protein ◽  
Lower Molecular Weight Species

SUMMARYA 230000 molecular weightPlasmodium yoeliiprotective antigen was characterized. Two monoclonal antibodies againstP. yoeliiimmunoprecipitated the 230000 mol. wt protein and a number of lower molecular weight polypeptides. These polypeptides were shown by peptide mapping and specific antibody binding to be fragments of the large protein. Iodination experiments suggested that the lower molecular weight species may be present on the surface of the merozoite. The protein was found not to be glycosylated. By serology, related antigens were shown to be associated with blood-stage schizonts ofP. vinckeisubspp.,P. chabaudisubspp. andP. falciparum.

scholarly journals Refining the transcriptome of the human malaria parasite Plasmodium falciparum using amplification-free RNA-seq

2019 ◽  
Author(s):  
Lia Chappell ◽  
Philipp Ross ◽  
Lindsey Orchard ◽  
Thomas D. Otto ◽  
Matthew Berriman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Developmental Cycle ◽  
Rna Seq ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Intraerythrocytic Developmental Cycle ◽  
Transcriptional Start Sites

AbstractPlasmodium parasites undergo several major developmental transitions during their complex lifecycle, which are enabled by precisely ordered gene expression programs. Transcriptomes from the 48-hour blood stages of the major human malaria parasite Plasmodium falciparum have been described using cDNA microarrays and RNA-seq, but these assays have not always performed well within non-coding regions, where the AT-content is often 90-95%. We developed a directional, amplification-free RNA-seq protocol (DAFT-seq) to reduce bias against AT-rich cDNA, which we have applied to three strains of P. falciparum (3D7, HB3 and IT). While strain-specific differences were detected, overall there is strong conservation between the transcriptional profiles. For the 3D7 reference strain, transcription was detected from 89% of the genome, with over 75% of the genome transcribed into mRNAs. These datasets allowed us to refine the 5’ and 3’ untranslated regions (UTRs), which can be variable, long (>1,000 nt), and often overlap those of adjacent transcripts. We also find that transcription from bidirectional promoters frequently results in non-coding, antisense transcripts. By capturing the 5’ ends of mRNAs, we reveal both constant and dynamic use of transcriptional start sites across the intraerythrocytic developmental cycle resulting in an updated view of the P. falciparum transcriptome.

scholarly journals Polymorphism of a high molecular weight schizont antigen of the human malaria parasite Plasmodium falciparum.

1985 ◽  
Vol 161 (1) ◽  
pp. 160-180 ◽  
Author(s):  
J S McBride ◽  
C I Newbold ◽  
R Anand
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Peptide Mapping ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Immunological Classification ◽  
Specific Antigens

Intraspecies antigenic diversity in the blood stages of the human malaria parasite Plasmodium falciparum was investigated using a collection of murine monoclonal antibodies and clones of the parasite. The results were as follows: (a) The schizont and merozoite stages of the parasite express on their surface clonally restricted antigens detectable by strain-specific antibodies in indirect immunofluorescence tests. (b) These restricted antigens are phenotypically stable characteristics of clones grown in vitro. (c) The molecules carrying the specific antigens were isolated by immunoprecipitation and were found to be parasite proteins ranging in size from Mr 190,000 to 200,000 between clones. (d) Comparative immunoprecipitation and peptide mapping of these molecules showed that each parasite clone expresses a protein that is antigenically and structurally distinct from the equivalent products of several other clones. (e) The different clonal products are, however, immunologically interrelated, since they possess determinants in common with all tested isolates of the parasite. (f) These polymorphic molecules are closely related to a previously described schizont protein of P. falciparum that is posttranslationally cleaved into fragments located on the merozoite surface. These findings show the existence of a family of related polymorphic schizont antigens (PSA) of P. falciparum, whose expression is clonally restricted, and indicate that these proteins have regions of constant and variable antigenicity. We propose that a system of immunological classification of the parasite can be developed based on the polymorphism of these proteins.

scholarly journals An intrinsic oscillator drives the blood stage cycle of the malaria parasite Plasmodium falciparum

Science ◽  
2020 ◽  
Vol 368 (6492) ◽  
pp. 754-759 ◽  
Author(s):  
Lauren M. Smith ◽  
Francis C. Motta ◽  
Garima Chopra ◽  
J. Kathleen Moch ◽  
Robert R. Nerem ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Blood Stage ◽  
Developmental Cycle ◽  
Cycle Period ◽  
Molecular Signatures ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Cell Variance

The blood stage of the infection of the malaria parasite Plasmodium falciparum exhibits a 48-hour developmental cycle that culminates in the synchronous release of parasites from red blood cells, which triggers 48-hour fever cycles in the host. This cycle could be driven extrinsically by host circadian processes or by a parasite-intrinsic oscillator. To distinguish between these hypotheses, we examine the P. falciparum cycle in an in vitro culture system and show that the parasite has molecular signatures associated with circadian and cell cycle oscillators. Each of the four strains examined has a different period, which indicates strain-intrinsic period control. Finally, we demonstrate that parasites have low cell-to-cell variance in cycle period, on par with a circadian oscillator. We conclude that an intrinsic oscillator maintains Plasmodium’s rhythmic life cycle.

scholarly journals Alteration in cytoadherence and rosetting of Plasmodium falciparum- infected thalassemic red blood cells

Blood ◽  
1993 ◽  
Vol 82 (12) ◽  
pp. 3752-3759 ◽  
Author(s):  
R Udomsangpetch ◽  
T Sueblinvong ◽  
K Pattanapanyasat ◽  
A Dharmkrong-at ◽  
A Kittikalayawong ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Blood Cell ◽  
Red Blood Cells ◽  
Red Blood Cell ◽  
Blood Cells ◽  
Protective Role ◽  
Immune Serum ◽  
Schizont Stage ◽  
Ring Stage

Abstract Hemoglobinopathies have a protective role in malaria that appears to be related to alterations in red blood cell (RBC) properties. Thalassemic RBCs infected with Plasmodium falciparum showed greatly reduced cytoadherence and rosetting properties as well as impaired growth and multiplication. A significant decrease in the levels of falciparum antigens associated with the membrane of infected beta-thalassemic RBCs was observed at trophozoite/schizont stage, but not young ring stage. This reduction was shown when a cytoadherence inhibitory monoclonal antibody, but not a noninhibitory pooled immune serum, was used. These observations suggest that protection against malaria in thalassemia is caused by both reduced parasitemias and altered adherence properties of the infected thalassemic RBCs that promote enhanced clearance of the parasite from the circulation.

scholarly journals The three major antigens on the surface of Plasmodium falciparum merozoites are derived from a single high molecular weight precursor.

1984 ◽  
Vol 160 (2) ◽  
pp. 624-629 ◽  
Author(s):  
A A Holder ◽  
R R Freeman
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibody ◽  
Plasmodium Falciparum ◽  
Affinity Chromatography ◽  
High Molecular Weight ◽  
Surface Antigens ◽  
Antibody Affinity ◽  
Major Surface ◽  
Falciparum Protein

A 195,000 mol wt Plasmodium falciparum protein and processing fragments derived from it have been purified by monoclonal antibody affinity chromatography. A polyvalent antiserum has been raised against the purified protein and used to identify the terminal processing products associated with the merozoite. Three unique fragments of 83,000, 42,000, and 19,000 mol wt are present and they represent the major surface antigens of P. falciparum merozoites.

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