title: A chemical susceptibility profile of the Plasmodium falciparum transmission stages by complementary cell-based gametocyte assays.
abstract: OBJECTIVE
  As most available antimalarial drugs are ineffective against the Plasmodium falciparum transmission stages, new drugs against the parasite's gametocytes are urgently needed to combat malaria globally. The unique biology of gametocytes requires assays that need to be specific, to faithfully monitor anti-gametocyte activity, and to be easy to perform, cheap and scalable to high-throughput screening (HTS).
  
  
  METHODS
  We developed an HTS cell-based assay with P. falciparum gametocytes specifically expressing a potent luciferase. To confirm HTS hit activity for several parasite genotypes, the luciferase assay and the gametocyte lactate dehydrogenase (LDH) assay, usable on any parasite isolate, were compared by screening antimalarial drugs and determining IC50 values of anti-gametocyte hits from the 'Malaria Box' against early- and late-stage gametocytes.
  
  
  RESULTS
  Comparison of the two assays, conducted on the early and on late gametocyte stages, revealed an excellent correlation (R(2) > 0.9) for the IC50 values obtained by the respective readouts. Differences in susceptibility to drugs and compounds between the two parasite developmental stages were consistently measured in both assays.
  
  
  CONCLUSIONS
  This work indicates that the luciferase and gametocyte LDH assays are interchangeable and that their specific advantages can be exploited to design an HTS pipeline leading to new transmission-blocking compounds. Results from these assays consistently defined a gametocyte chemical susceptibility profile, relevant to the planning of future drug discovery strategies.
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
authors.forename: Sarah
authors.initials: S
authors.lastname: D'Alessandro
authors.affiliation: Dipartimento di Malattie Infettive, Parassitarie, Immunomediate, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Grazia
authors.initials: G
authors.lastname: Camarda
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Corbett
authors.affiliation: Dipartimento di Malattie Infettive, Parassitarie, Immunomediate, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Siciliano
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Parapini
authors.affiliation: Dipartimento di Chimica 'G. Ciamician', Università di Bologna, Bologna, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cevenini
authors.affiliation: Dipartimento di Chimica 'G. Ciamician', Università di Bologna, Bologna, Italy Istituto Nazionale Biostrutture e Biosistemi (INBB), Roma, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Michelini
authors.affiliation: Dipartimento di Chimica 'G. Ciamician', Università di Bologna, Bologna, Italy Istituto Nazionale Biostrutture e Biosistemi (INBB), Roma, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Roda
authors.affiliation: Medicines for Malaria Venture, Geneva, Switzerland.
authors.forename: Didier
authors.initials: D
authors.lastname: Leroy
authors.affiliation: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Taramelli
authors.affiliation: Dipartimento di Malattie Infettive, Parassitarie, Immunomediate, Istituto Superiore di Sanità, Rome, Italy alano@iss.it.
authors.forename: Pietro
authors.initials: P
authors.lastname: Alano
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D003584:Cytological Techniques / Q000379:methods; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D017930:Genes, Reporter; D057166:High-Throughput Screening Assays / Q000379:methods; D006801:Humans; D020128:Inhibitory Concentration 50; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008156:Luciferases / Q000032:analysis; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology; D013194:Staining and Labeling
chemical_list: D000962:Antimalarials; D007770:L-Lactate Dehydrogenase; D008156:Luciferases