title: A Plasmodium falciparum screening assay for anti-gametocyte drugs based on parasite lactate dehydrogenase detection.
abstract: OBJECTIVE
  Plasmodium gametocytes, responsible for malaria parasite transmission from humans to mosquitoes, represent a crucial target for new antimalarial drugs to achieve malaria elimination/eradication. We developed a novel colorimetric screening method for anti-gametocyte compounds based on the parasite lactate dehydrogenase (pLDH) assay, already standardized for asexual stages, to measure gametocyte viability and drug susceptibility.
  
  
  METHODS
  Gametocytogenesis of 3D7 and NF54 Plasmodium falciparum strains was induced in vitro and asexual parasites were depleted with N-acetylglucosamine. Gametocytes were treated with dihydroartemisinin, epoxomicin, methylene blue, primaquine, puromycin or chloroquine in 96-well plates and the pLDH activity was evaluated using a modified Makler protocol. Mosquito infectivity was measured by the standard membrane feeding assay (SMFA).
  
  
  RESULTS
  A linear correlation was found between gametocytaemia determined by Giemsa staining and pLDH activity. A concentration-dependent reduction in pLDH activity was observed after 72 h of drug treatment, whereas an additional 72 h of incubation without drugs was required to obtain complete inhibition of gametocyte viability. SMFA on treated and control gametocytes confirmed that a reduction in pLDH activity translates into reduced oocyst development in the mosquito vector.
  
  
  CONCLUSIONS
  The gametocyte pLDH assay is fast, easy to perform, cheap and reproducible and is suitable for screening novel transmission-blocking compounds, which does not require parasite transgenic lines.
authors: Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, 20133 Milan, Italy.
authors: Sarah
authors: S
authors: D'Alessandro
authors: Francesco
authors: F
authors: Silvestrini
authors: Koen
authors: K
authors: Dechering
authors: Yolanda
authors: Y
authors: Corbett
authors: Silvia
authors: S
authors: Parapini
authors: Martijn
authors: M
authors: Timmerman
authors: Laura
authors: L
authors: Galastri
authors: Nicoletta
authors: N
authors: Basilico
authors: Robert
authors: R
authors: Sauerwein
authors: Pietro
authors: P
authors: Alano
authors: Donatella
authors: D
authors: Taramelli
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000302:isolation & purification* / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects*; D003124:Colorimetry / Q000379:methods; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology*
chemical_list: D000962:Antimalarials; D007770:L-Lactate Dehydrogenase
keywords: drug screening; gametocytes; malaria