@article{BoesSpiegelVoepeletal.2015, author = {Boes, Alexander and Spiegel, Holger and Voepel, Nadja and Edgue, Gueven and Beiss, Veronique and Kapelski, Stephanie and Fendel, Rolf and Scheuermayer, Matthias and Pradel, Gabriele and Bolscher, Judith M. and Behet, Marije C. and Dechering, Koen J. and Hermsen, Cornelus C. and Sauerwein, Robert W. and Schillberg, Stefan and Reimann, Andreas and Fischer, Rainer}, title = {Analysis of a multi-component multi-stage malaria vaccine candidate—tackling the cocktail challenge}, series = {PLoS ONE}, volume = {10}, journal = {PLoS ONE}, number = {7}, doi = {10.1371/journal.pone.0131456}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173092}, pages = {e0131456}, year = {2015}, abstract = {Combining key antigens from the different stages of the P. falciparum life cycle in the context of a multi-stage-specific cocktail offers a promising approach towards the development of a malaria vaccine ideally capable of preventing initial infection, the clinical manifestation as well as the transmission of the disease. To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants. After immunization of rabbits we determined the domain-specific antibody titers as well as component-specific antibody concentrations and correlated them with stage specific in vitro efficacy. Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80\%), blood (up to 90\%) and sexual parasite stages (100\%). Based on the component-specific antibody concentrations we calculated the IC50 values for the pre-erythrocytic stage (17-25 μg/ml), the blood stage (40-60 μg/ml) and the sexual stage (1.75 μg/ml). While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.}, language = {en} } @article{vonBohlKuehnSimonetal.2015, author = {von Bohl, Andreas and Kuehn, Andrea and Simon, Nina and Nkwouano Ngongang, Vanesa and Spehr, Marc and Baumeister, Stefan and Przyborski, Jude M. and Fischer, Rainer and Pradel, Gabriele}, title = {A WD40-repeat protein unique to malaria parasites associates with adhesion protein complexes and is crucial for blood stage progeny}, series = {Malaria Journal}, volume = {14}, journal = {Malaria Journal}, number = {435}, doi = {10.1186/s12936-015-0967-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139728}, year = {2015}, abstract = {Background During development in human erythrocytes, Plasmodium falciparum parasites display a remarkable number of adhesive proteins on their plasma membrane. In the invasive merozoites, these include members of the PfMSP1 and PfAMA1/RON complexes, which facilitate contact between merozoites and red blood cells. In gametocytes, sexual precursor cells mediating parasite transmission to the mosquito vector, plasma membrane-associated proteins primarily belong to the PfCCp and 6-cys families with roles in fertilization. This study describes a newly identified WD40-repeat protein unique to Plasmodium species that associates with adhesion protein complexes of both merozoites and gametocytes. Methods The WD40-repeat protein-like protein PfWLP1 was identified via co-immunoprecipitation assays followed by mass spectrometry and characterized using biochemical and immunohistochemistry methods. Reverse genetics were employed for functional analysis. Results PfWLP1 is expressed both in schizonts and gametocytes. In mature schizonts, the protein localizes underneath the merozoite micronemes and interacts with PfAMA1, while in gametocytes PfWLP1 primarily accumulates underneath the plasma membrane and associates with PfCCp1 and Pfs230. Reverse genetics failed to disrupt the pfwlp1 gene, while haemagglutinin-tagging was feasible, suggesting a crucial function for PfWLP1 during blood stage replication. Conclusions This is the first report on a plasmodial WD40-repeat protein associating with cell adhesion proteins. Since WD40 domains are known to mediate protein-protein contact by serving as a rigid scaffold for protein interactions, the presented data suggest that PfWLP1 supports the stability of adhesion protein complexes of the plasmodial blood stages.}, language = {en} } @article{MakoahNigelArndtPradel2012, author = {Makoah Nigel, Animake and Arndt, Hans-Dieter and Pradel, Gabriele}, title = {The proteasome of malaria parasites: A multi-stage drug target for chemotherapeutic intervention?}, series = {International Journal for Parasitology: Drugs and Drug Resistance}, volume = {2}, journal = {International Journal for Parasitology: Drugs and Drug Resistance}, doi = {10.1016/j.ijpddr.2011.12.001}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137777}, pages = {1-10}, year = {2012}, abstract = {The ubiquitin/proteasome system serves as a regulated protein degradation pathway in eukaryotes, and is involved in many cellular processes featuring high protein turnover rates, such as cell cycle control, stress response and signal transduction. In malaria parasites, protein quality control is potentially important because of the high replication rate and the rapid transformations of the parasite during life cycle progression. The proteasome is the core of the degradation pathway, and is a major proteolytic complex responsible for the degradation and recycling of non-functional ubiquitinated proteins. Annotation of the genome for Plasmodium falciparum, the causative agent of malaria tropica, revealed proteins with similarity to human 26S proteasome subunits. In addition, a bacterial ClpQ/hslV threonine peptidase-like protein was identified. In recent years several independent studies indicated an essential function of the parasite proteasome for the liver, blood and transmission stages. In this review, we compile evidence for protein recycling in Plasmodium parasites and discuss the role of the 26S proteasome as a prospective multi-stage target for antimalarial drug discovery programs.}, language = {en} } @article{RoehrichNgwaWiesneretal.2012, author = {R{\"o}hrich, Christian Rene and Ngwa, Che Julius and Wiesner, Jochen and Schmidtberg, Henrike and Degenkolb, Thomas and Kollewe, Christian and Fischer, Rainer and Pradel, Gabriele and Vilcinskas, Andreas}, title = {Harmonine, a defence compound from the harlequin ladybird, inhibits mycobacterial growth and demonstrates multi-stage antimalarial activity}, series = {Biology Letters}, volume = {8}, journal = {Biology Letters}, doi = {10.1098/rsbl.2011.0760}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-127079}, pages = {308-311}, year = {2012}, abstract = {The harlequin ladybird beetle Harmonia axyridis has been introduced in many countries as a biological control agent, but has become an invasive species threatening the biodiversity of native ladybirds. Its invasive success has been attributed to its vigorous resistance against diverse pathogens. This study demonstrates that harmonine ((17R,9Z)-1,17-diaminooctadec-9-ene), which is present in H. axyridis haemolymph, displays broad-spectrum antimicrobial activity that includes human pathogens. Antibacterial activity is most pronounced against fast-growing mycobacteria and Mycobacterium tuberculosis, and the growth of both chloroquine-sensitive and -resistant Plasmodium falciparum strains is inhibited. Harmonine displays gametocytocidal activity, and inhibits the exflagellation of microgametocytes and zygote formation. In an Anopheles stephensi mosquito feeding model, harmonine displays transmission-blocking activity.}, language = {en} } @article{FellerThomKochetal.2013, author = {Feller, Tatjana and Thom, Pascal and Koch, Natalie and Spiegel, Holger and Addai-Mensah, Otchere and Fischer, Rainer and Reimann, Andreas and Pradel, Gabriele and Fendel, Rolf and Schillberg, Stefan and Scheuermayer, Matthias and Schinkel, Helga}, title = {Plant-Based Production of Recombinant Plasmodium Surface Protein Pf38 and Evaluation of its Potential as a Vaccine Candidate}, series = {PLOS ONE}, volume = {8}, journal = {PLOS ONE}, number = {11}, issn = {1932-6203}, doi = {10.1371/journal.pone.0079920}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128221}, pages = {e79920}, year = {2013}, abstract = {Pf38 is a surface protein of the malarial parasite Plasmodium falciparum. In this study, we produced and purified recombinant Pf38 and a fusion protein composed of red fluorescent protein and Pf38 (RFP-Pf38) using a transient expression system in the plant Nicotiana benthamiana. To our knowledge, this is the first description of the production of recombinant Pf38. To verify the quality of the recombinant Pf38, plasma from semi-immune African donors was used to confirm specific binding to Pf38. ELISA measurements revealed that immune responses to Pf38 in this African subset were comparable to reactivities to AMA-1 and \(MSP1_{19}\). Pf38 and RFP-Pf38 were successfully used to immunise mice, although titres from these mice were low (on average 1:11.000 and 1:39.000, respectively). In immune fluorescence assays, the purified IgG fraction from the sera of immunised mice recognised Pf38 on the surface of schizonts, gametocytes, macrogametes and zygotes, but not sporozoites. Growth inhibition assays using \(\alpha Pf38\) antibodies demonstrated strong inhibition \((\geq 60 \\% ) \) of the growth of blood-stage P. falciparum. The development of zygotes was also effectively inhibited by \(\alpha Pf38\) antibodies, as determined by the zygote development assay. Collectively, these results suggest that Pf38 is an interesting candidate for the development of a malaria vaccine.}, language = {en} } @article{KuehnPradel2010, author = {Kuehn, Andrea and Pradel, Gabriele}, title = {The Coming-Out of Malaria Gametocytes [Review Article]}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68196}, year = {2010}, abstract = {The tropical disease malaria, which results in more than one million deaths annually, is caused by protozoan parasites of the genus Plasmodium and transmitted by blood-feeding Anopheline mosquitoes. Parasite transition from the human host to the mosquito vector is mediated by gametocytes, sexual stages that are formed in human erythrocytes, which therefore play a crucial part in the spread of the tropical disease. The uptake by the blood-feeding mosquito triggers important molecular and cellular changes in the gametocytes, thus mediating the rapid adjustment of the parasite from the warm-blooded host to the insect host and subsequently initiating reproduction. The contact with midgut factors triggers gametocyte activation and results in their egress from the enveloping erythrocyte, which then leads to gamete formation and fertilization. This review summarizes recent findings on the role of gametocytes during transmission to themosquito and particularly focuses on the molecular mechanisms underlying gametocyte activation and emergence from the host erythrocyte during gametogenesis.}, subject = {Malaria}, language = {en} }