A set of independent selectable markers for transfection of the human malaria parasite Plasmodium falciparum.
Genomic information is rapidly accumulating for the human malaria pathogen, Plasmodium falciparum. Our ability to perform genetic manipulations to understand Plasmodium gene function is limited. Dihydrofolate reductase is the only selectable marker presently available for transfection of P. falciparum. Additional markers are needed for complementation and for expression of mutated forms of essential genes. We tested parasite sensitivity to different drugs for which selectable markers are available. Two of these drugs that were very effective as antiplasmodial inhibitors in culture, blasticidin and geneticin (G418), were selected for further study. The genes BSD, encoding blasticidin S deaminase of Aspergillus terreus, and NEO, encoding neomycin phosphotransferase II from transposon Tn 5, were expressed under the histidine-rich protein III (HRPIII) gene promoter and tested for their ability to confer resistance to blasticidin or G418, respectively. After transfection, blasticidin and G418-resistant parasites tested positive for plasmid replication and BSD or NEO expression. Cross-resistance assays indicate that these markers are independent. The plasmid copy number and the enzymatic activity depended directly on the concentration of the drug used for selection. These markers set the stage for new methods of functional analysis of the P. falciparum genome.
Department of Molecular Microbiology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8230, St. Louis, MO 63110, USA.
C B
CB
Mamoun
I Y
IY
Gluzman
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S
Goyard
S M
SM
Beverley
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DE
Goldberg
D000619:Aminohydrolases / Q000235:genetics; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology; D001230:Aspergillus / Q000201:enzymology / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D004261:DNA Replication / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D018628:Gene Dosage; D005819:Genetic Markers; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D019868:Kanamycin Kinase / Q000235:genetics; D009705:Nucleosides / Q000494:pharmacology; D010963:Plasmodium falciparum / Q000235:genetics* / Q000472:pathogenicity; D012150:Polymorphism, Restriction Fragment Length; D011401:Promoter Regions, Genetic; D014162:Transfection
D000962:Antimalarials; D004251:DNA Transposable Elements; D005819:Genetic Markers; D005839:Gentamicins; D009705:Nucleosides; C004500:blasticidin S; C010680:antibiotic G 418; D019868:Kanamycin Kinase; D000619:Aminohydrolases; C019795:blasticidin S deaminase