Defining multiplicity of vector uptake in transfected Plasmodium parasites

Manuela Carrasquilla, Sophie Adjalley, Theo Sanderson, Alejandro Marin-Menendez, Rachael Coyle, Ruddy Montandon, Julian C Rayner, Alena Pance, Marcus C S Lee

Research output: Contribution to journalArticlepeer-review


The recurrent emergence of drug resistance in Plasmodium falciparum increases the urgency to genetically validate drug resistance mechanisms and identify new targets. Reverse genetics have facilitated genome-scale knockout screens in Plasmodium berghei and Toxoplasma gondii, in which pooled transfections of multiple vectors were critical to increasing scale and throughput. These approaches have not yet been implemented in human malaria species such as P. falciparum and P. knowlesi, in part because the extent to which pooled transfections can be performed in these species remains to be evaluated. Here we use next-generation sequencing to quantitate uptake of a pool of 94 barcoded vectors. The distribution of vector acquisition allowed us to estimate the number of barcodes and DNA molecules taken up by the parasite population. Dilution cloning of P. falciparum transfectants showed that individual clones possess as many as seven episomal barcodes, revealing that an intake of multiple vectors is a frequent event despite the inefficient transfection efficiency. Transfection of three spectrally-distinct fluorescent reporters allowed us to evaluate different transfection methods and revealed that schizont-stage transfection limited the tendency for parasites to take up multiple vectors. In contrast to P. falciparum, we observed that the higher transfection efficiency of P. knowlesi resulted in near complete representation of the library. These findings have important implications for how reverse genetics can be scaled in culturable Plasmodium species.

Original languageEnglish
Pages (from-to)10894
JournalScientific Reports
Issue number1
Publication statusPublished - 2 Jul 2020


  • Biological Transport
  • Calmodulin/genetics
  • Clone Cells
  • DNA Barcoding, Taxonomic
  • DNA, Recombinant/metabolism
  • Electroporation
  • Erythrocytes/parasitology
  • Flow Cytometry
  • Gene Library
  • Genetic Vectors/genetics
  • Humans
  • Luminescent Proteins/genetics
  • Plasmids/genetics
  • Plasmodium falciparum/genetics
  • Plasmodium knowlesi/genetics
  • Promoter Regions, Genetic
  • Species Specificity
  • Transfection/methods


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