scholarly journals Pre-erythrocytic antibody profiles induced by controlled human malaria infections in healthy volunteers under chloroquine prophylaxis

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Philip L. Felgner ◽  
Meta Roestenberg ◽  
Li Liang ◽  
Christopher Hung ◽  
Aarti Jain ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Healthy Volunteers ◽  
Protective Immunity ◽  
Circumsporozoite Protein ◽  
Blood Stage ◽  
Asexual Blood Stage ◽  
Liver Stage ◽  
Human Malaria ◽  
Life Cycle Stages

Abstract Complete sterile protection to Plasmodium falciparum (Pf) infection mediated by pre-erythrocytic immunity can be experimentally induced under chloroquine prophylaxis, through immunization with sporozoites from infected mosquitoes' bites (CPS protocol). To characterize the profile of CPS induced antibody (Ab) responses, we developed a proteome microarray containing 809 Pf antigens showing a distinct Ab profile with recognition of antigens expressed in pre-erythrocytic life-cycle stages. In contrast, plasma from naturally exposed semi-immune individuals from Kenya was skewed toward antibody reactivity against asexual blood stage antigens. CPS-immunized and semi-immune individuals generated antibodies against 192 and 202 Pf antigens, respectively, but only 60 antigens overlapped between the two groups. Although the number of reactive antigens varied between the CPS-immunized individuals, all volunteers reacted strongly against the pre-erythrocytic antigens circumsporozoite protein (CSP) and liver stage antigen 1 (LSA1). Well classified merozoite and erythrocytic antigens were strongly reactive in semi-immune individuals but lacking in the CPS immunized group. These data show that the antibody profile of CPS-immunized and semi-immune groups have quite distinct profiles reflecting their protective immunity; antibodies from CPS immunized individuals react strongly against pre-erythrocytic while semi-immune individuals mainly react against erythrocytic antigens.

scholarly journals Chemoprotective antimalarials identified through quantitative high-throughput screening of Plasmodium blood and liver stage parasites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dorjbal Dorjsuren ◽  
Richard T. Eastman ◽  
Kathryn J. Wicht ◽  
Daniel Jansen ◽  
Daniel C. Talley ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
High Throughput ◽  
High Throughput Screening ◽  
Large Scale ◽  
Blood Stage ◽  
Response Curves ◽  
Asexual Blood Stage ◽  
Liver Stage ◽  
Resistance Selection ◽  
Parasite Biology

AbstractThe spread of Plasmodium falciparum parasites resistant to most first-line antimalarials creates an imperative to enrich the drug discovery pipeline, preferably with curative compounds that can also act prophylactically. We report a phenotypic quantitative high-throughput screen (qHTS), based on concentration–response curves, which was designed to identify compounds active against Plasmodium liver and asexual blood stage parasites. Our qHTS screened over 450,000 compounds, tested across a range of 5 to 11 concentrations, for activity against Plasmodium falciparum asexual blood stages. Active compounds were then filtered for unique structures and drug-like properties and subsequently screened in a P. berghei liver stage assay to identify novel dual-active antiplasmodial chemotypes. Hits from thiadiazine and pyrimidine azepine chemotypes were subsequently prioritized for resistance selection studies, yielding distinct mutations in P. falciparum cytochrome b, a validated antimalarial drug target. The thiadiazine chemotype was subjected to an initial medicinal chemistry campaign, yielding a metabolically stable analog with sub-micromolar potency. Our qHTS methodology and resulting dataset provides a large-scale resource to investigate Plasmodium liver and asexual blood stage parasite biology and inform further research to develop novel chemotypes as causal prophylactic antimalarials.

scholarly journals Type II Fatty Acid Biosynthesis Is Essential for Plasmodium falciparum Sporozoite Development in the Midgut of Anopheles Mosquitoes

2013 ◽  
Vol 13 (5) ◽  
pp. 550-559 ◽  
Author(s):  
Ben C. L. van Schaijk ◽  
T. R. Santha Kumar ◽  
Martijn W. Vos ◽  
Adam Richman ◽  
Geert-Jan van Gemert ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Plasmodium Falciparum ◽  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Blood Stage ◽  
Acid Biosynthesis ◽  
Asexual Blood Stage ◽  
Liver Stage ◽  
Content Type ◽  
Fas Ii

ABSTRACT The prodigious rate at which malaria parasites proliferate during asexual blood-stage replication, midgut sporozoite production, and intrahepatic development creates a substantial requirement for essential nutrients, including fatty acids that likely are necessary for parasite membrane formation. Plasmodium parasites obtain fatty acids either by scavenging from the vertebrate host and mosquito vector or by producing fatty acids de novo via the type two fatty acid biosynthesis pathway (FAS-II). Here, we study the FAS-II pathway in Plasmodium falciparum , the species responsible for the most lethal form of human malaria. Using antibodies, we find that the FAS-II enzyme FabI is expressed in mosquito midgut oocysts and sporozoites as well as liver-stage parasites but not during the blood stages. As expected, FabI colocalizes with the apicoplast-targeted acyl carrier protein, indicating that FabI functions in the apicoplast. We further analyze the FAS-II pathway in Plasmodium falciparum by assessing the functional consequences of deleting fabI and fabB/F . Targeted deletion or disruption of these genes in P. falciparum did not affect asexual blood-stage replication or the generation of midgut oocysts; however, subsequent sporozoite development was abolished. We conclude that the P. falciparum FAS-II pathway is essential for sporozoite development within the midgut oocyst. These findings reveal an important distinction from the rodent Plasmodium parasites P. berghei and P. yoelii , where the FAS-II pathway is known to be required for normal parasite progression through the liver stage but is not required for oocyst development in the Anopheles mosquito midgut.

scholarly journals The Basal Complex Protein PfMORN1 Is Not Required for Asexual Replication of Plasmodium falciparum

mSphere ◽  
2021 ◽  
Author(s):  
Colleen J. Moran ◽  
Jeffrey D. Dvorin
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Severe Form ◽  
Blood Stage ◽  
Content Type ◽  
Human Malaria ◽  
Basal Complex ◽  
Complex Protein

Plasmodium falciparum parasites cause the most severe form of human malaria. During the clinically relevant blood stage of its life cycle, the parasites divide via schizogony.

scholarly journals Probing Plasmodium falciparum sexual commitment at the single-cell level

2018 ◽  
Vol 3 ◽  
pp. 70 ◽  
Author(s):  
Nicolas M.B. Brancucci ◽  
Mariana De Niz ◽  
Timothy J. Straub ◽  
Deepali Ravel ◽  
Lauriane Sollelis ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Single Cell ◽  
Transcriptional Profiling ◽  
Quantitative Imaging ◽  
Complex Life Cycle ◽  
Major Transitions ◽  
Transcriptional Signature ◽  
Life Cycle Stages ◽  
Parasite Populations

Background: Malaria parasites go through major transitions during their complex life cycle, yet the underlying differentiation pathways remain obscure. Here we apply single cell transcriptomics to unravel the program inducing sexual differentiation in Plasmodium falciparum. Parasites have to make this essential life-cycle decision in preparation for human-to-mosquito transmission. Methods: By combining transcriptional profiling with quantitative imaging and genetics, we defined a transcriptional signature in sexually committed cells. Results: We found this transcriptional signature to be distinct from general changes in parasite metabolism that can be observed in response to commitment-inducing conditions. Conclusions: This proof-of-concept study provides a template to capture transcriptional diversity in parasite populations containing complex mixtures of different life-cycle stages and developmental programs, with important implications for our understanding of parasite biology and the ongoing malaria elimination campaign.

scholarly journals Progress towards a broadly neutralizing vaccine against the asexual blood-stage of Plasmodium falciparum

2013 ◽  
Vol 4 ◽  
Author(s):  
Douglas Alexander ◽  
Williams Andrew ◽  
Illingworth Joseph ◽  
Hjerrild Kathryn ◽  
Draper Simon
Keyword(s):  
Plasmodium Falciparum ◽  
Blood Stage ◽  
Asexual Blood Stage

scholarly journals The Malaria Parasite Cyclic GMP-Dependent Protein Kinase Plays a Central Role in Blood-Stage Schizogony

2009 ◽  
Vol 9 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Helen M. Taylor ◽  
Louisa McRobert ◽  
Munira Grainger ◽  
Audrey Sicard ◽  
Anton R. Dluzewski ◽  
...  
Keyword(s):  
Life Cycle ◽  
Protein Kinase ◽  
Cyclic Gmp ◽  
Malaria Parasite ◽  
Kinase Inhibitor ◽  
Blood Stage ◽  
Parasite Life Cycle ◽  
Dependent Protein Kinase ◽  
Asexual Blood Stage ◽  
Dependent Protein

ABSTRACT A role for the Plasmodium falciparum cyclic GMP (cGMP)-dependent protein kinase (PfPKG) in gametogenesis in the malaria parasite was elucidated previously. In the present study we examined the role of PfPKG in the asexual blood-stage of the parasite life cycle, the stage that causes malaria pathology. A specific PKG inhibitor (compound 1, a trisubstituted pyrrole) prevented the progression of P. falciparum schizonts through to ring stages in erythrocyte invasion assays. Addition of compound 1 to ring-stage parasites allowed normal development up to 30 h postinvasion, and segmented schizonts were able to form. However, synchronized schizonts treated with compound 1 for ≥6 h became large and dysmorphic and were unable to rupture or liberate merozoites. To conclusively demonstrate that the effect of compound 1 on schizogony was due to its selective action on PfPKG, we utilized genetically manipulated P. falciparum parasites expressing a compound 1-insensitive PfPKG. The mutant parasites were able to complete schizogony in the presence of compound 1 but not in the presence of the broad-spectrum protein kinase inhibitor staurosporine. This shows that PfPKG is the primary target of compound 1 during schizogony and provides direct evidence of a role for PfPKG in this process. Discovery of essential roles for the P. falciparum PKG in both asexual and sexual development demonstrates that cGMP signaling is a key regulator of both of these crucial life cycle phases and defines this molecule as an exciting potential drug target for both therapeutic and transmission blocking action against malaria.

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