In Vitro and in Vivo Adaptation of the Geneve/SGE-1 Strain of Plasmodium falciparum to Growth in a Squirrel Monkey (Saimiri sciureus) Model

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

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Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽

10.1182/blood.v76.6.1250.1250 ◽

1990 ◽

Vol 76 (6) ◽

pp. 1250-1255 ◽

Cited By ~ 36

Author(s):

S Whitehead ◽

TE Peto

Keyword(s):

Plasmodium Falciparum ◽

Growth Inhibition ◽

Antimalarial Activity ◽

Clinical Malaria ◽

Inhibitory Effect ◽

Parasite Development ◽

And Control ◽

Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

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In vitro and in vivo inhibition of malaria parasite infection by monoclonal antibodies against Plasmodium falciparum circumsporozoite protein (CSP)

Scientific Reports ◽

10.1038/s41598-021-84622-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Merricka C. Livingstone ◽

Alexis A. Bitzer ◽

Alish Giri ◽

Kun Luo ◽

Rajeshwer S. Sankhala ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Monoclonal Antibodies ◽

Disease Burden ◽

Vaccine Candidate ◽

Specific Binding ◽

Circumsporozoite Protein ◽

Target Epitope ◽

Selection Of

AbstractPlasmodium falciparum malaria contributes to a significant global disease burden. Circumsporozoite protein (CSP), the most abundant sporozoite stage antigen, is a prime vaccine candidate. Inhibitory monoclonal antibodies (mAbs) against CSP map to either a short junctional sequence or the central (NPNA)n repeat region. We compared in vitro and in vivo activities of six CSP-specific mAbs derived from human recipients of a recombinant CSP vaccine RTS,S/AS01 (mAbs 317 and 311); an irradiated whole sporozoite vaccine PfSPZ (mAbs CIS43 and MGG4); or individuals exposed to malaria (mAbs 580 and 663). RTS,S mAb 317 that specifically binds the (NPNA)n epitope, had the highest affinity and it elicited the best sterile protection in mice. The most potent inhibitor of sporozoite invasion in vitro was mAb CIS43 which shows dual-specific binding to the junctional sequence and (NPNA)n. In vivo mouse protection was associated with the mAb reactivity to the NANPx6 peptide, the in vitro inhibition of sporozoite invasion activity, and kinetic parameters measured using intact mAbs or their Fab fragments. Buried surface area between mAb and its target epitope was also associated with in vivo protection. Association and disconnects between in vitro and in vivo readouts has important implications for the design and down-selection of the next generation of CSP based interventions.

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Antigenicity of the infected-erythrocyte and merozoite surfaces in Falciparum malaria.

Journal of Experimental Medicine ◽

10.1084/jem.150.5.1241 ◽

1979 ◽

Vol 150 (5) ◽

pp. 1241-1254 ◽

Cited By ~ 62

Author(s):

S G Langreth ◽

R T Reese

Keyword(s):

Plasmodium Falciparum ◽

Falciparum Malaria ◽

Infected Erythrocyte ◽

Falciparum Infection ◽

Human Erythrocytes ◽

Cross Linking ◽

Common Antigens

The antigenicity of altered structures induced by Plasmodium falciparum in the membranes of infected Aotus monkey and human erythrocytes was examined. Antisera were obtained from monkeys made immune to malaria. Bound antibodies were shown to be localized on the knob protrusions of infected erythrocytes of both human and monkey origin and from both in vitro and in vivo infections. Therefore, P. falciparum infection has produced similar antigenic changes in the erythrocyte surfaces of both man and monkey. Uninfected erythrocytes and all knobless-infected erythrocytes bound no antibody from immune sera. Strains of P. falciparum from widely different geographic areas that were cultured in vitro in human erythrocytes induced structures (knobs) which have common antigenicity. Merozoites were agglutinated by cross-linking of their cell coats when incubated with immune sera. The binding of ferritin-labeled antibody was heavy on the coats of both homologous and heterologous strains of the parasite, indicating that the merozoite surfaces of these strains share common antigens.

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The Sites of Sequestration of the Uganda-Palo Alto Strain of Plasmodium falciparum-Infected Red Blood Cells in the Squirrel Monkey, Saimiri sciureus

Journal of Parasitology ◽

10.2307/3278382 ◽

1974 ◽

Vol 60 (3) ◽

pp. 534 ◽

Cited By ~ 10

Author(s):

Henry N. Fremount ◽

Richard N. Rossan

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Squirrel Monkey ◽

Blood Cells ◽

Saimiri Sciureus ◽

Palo Alto

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Antimalarial activity of betulinic acid and derivatives in vitro against Plasmodium falciparum and in vivo in P. berghei-infected mice

Parasitology Research ◽

10.1007/s00436-009-1394-0 ◽

2009 ◽

Vol 105 (1) ◽

pp. 275-279 ◽

Cited By ~ 46

Author(s):

Matheus Santos de Sá ◽

José Fernando Oliveira Costa ◽

Antoniana Ursine Krettli ◽

Mariano Gustavo Zalis ◽

Gabriela Lemos de Azevedo Maia ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Betulinic Acid ◽

Antimalarial Activity

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The Plasmodium falciparum circumsporozoite protein produced in Lactococcus lactis is pure and stable

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.011268 ◽

2019 ◽

Vol 295 (2) ◽

pp. 403-414 ◽

Cited By ~ 1

Author(s):

Susheel K. Singh ◽

Jordan Plieskatt ◽

Bishwanath Kumar Chourasia ◽

Vandana Singh ◽

Judith M. Bolscher ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Lactococcus Lactis ◽

Malaria Vaccine ◽

Vaccine Development ◽

Expression System ◽

Surface Protein ◽

Circumsporozoite Protein ◽

Full Length

The Plasmodium falciparum circumsporozoite protein (PfCSP) is a sporozoite surface protein whose role in sporozoite motility and cell invasion has made it the leading candidate for a pre-erythrocytic malaria vaccine. However, production of high yields of soluble recombinant PfCSP, including its extensive NANP and NVDP repeats, has proven problematic. Here, we report on the development and characterization of a secreted, soluble, and stable full-length PfCSP (containing 4 NVDP and 38 NANP repeats) produced in the Lactococcus lactis expression system. The recombinant full-length PfCSP, denoted PfCSP4/38, was produced initially with a histidine tag and purified by a simple two-step procedure. Importantly, the recombinant PfCSP4/38 retained a conformational epitope for antibodies as confirmed by both in vivo and in vitro characterizations. We characterized this complex protein by HPLC, light scattering, MS analysis, differential scanning fluorimetry, CD, SDS-PAGE, and immunoblotting with conformation-dependent and -independent mAbs, which confirmed it to be both pure and soluble. Moreover, we found that the recombinant protein is stable at both frozen and elevated-temperature storage conditions. When we used L. lactis–derived PfCSP4/38 to immunize mice, it elicited high levels of functional antibodies that had the capacity to modify sporozoite motility in vitro. We concluded that the reported yield, purity, results of biophysical analyses, and stability of PfCSP4/38 warrant further consideration of using the L. lactis system for the production of circumsporozoite proteins for preclinical and clinical applications in malaria vaccine development.

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Computational Chemogenomics Drug Repositioning Strategy Enables the Discovery of Epirubicin as a New Repurposed Hit for Plasmodium falciparum and P. vivax

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02041-19 ◽

2020 ◽

Vol 64 (9) ◽

Author(s):

Letícia Tiburcio Ferreira ◽

Juliana Rodrigues ◽

Gustavo Capatti Cassiano ◽

Tatyana Almeida Tavella ◽

Kaira Cristina Peralis Tomaz ◽

...

Keyword(s):

Plasmodium Falciparum ◽

In Silico ◽

Antimalarial Activity ◽

Drug Repositioning ◽

Dna Gyrase ◽

Plasmodium Yoelii ◽

Computer Assisted ◽

Content Type

ABSTRACT Widespread resistance against antimalarial drugs thwarts current efforts for controlling the disease and urges the discovery of new effective treatments. Drug repositioning is increasingly becoming an attractive strategy since it can reduce costs, risks, and time-to-market. Herein, we have used this strategy to identify novel antimalarial hits. We used a comparative in silico chemogenomics approach to select Plasmodium falciparum and Plasmodium vivax proteins as potential drug targets and analyzed them using a computer-assisted drug repositioning pipeline to identify approved drugs with potential antimalarial activity. Among the seven drugs identified as promising antimalarial candidates, the anthracycline epirubicin was selected for further experimental validation. Epirubicin was shown to be potent in vitro against sensitive and multidrug-resistant P. falciparum strains and P. vivax field isolates in the nanomolar range, as well as being effective against an in vivo murine model of Plasmodium yoelii. Transmission-blocking activity was observed for epirubicin in vitro and in vivo. Finally, using yeast-based haploinsufficiency chemical genomic profiling, we aimed to get insights into the mechanism of action of epirubicin. Beyond the target predicted in silico (a DNA gyrase in the apicoplast), functional assays suggested a GlcNac-1-P-transferase (GPT) enzyme as a potential target. Docking calculations predicted the binding mode of epirubicin with DNA gyrase and GPT proteins. Epirubicin is originally an antitumoral agent and presents associated toxicity. However, its antiplasmodial activity against not only P. falciparum but also P. vivax in different stages of the parasite life cycle supports the use of this drug as a scaffold for hit-to-lead optimization in malaria drug discovery.

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