A modified in vitro sulfadoxine susceptibility assay for Plasmodium falciparum suitable for investigating Fansidar resistance

P. Wang, P. F G Sims, J. E. Hyde

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The combination of pyrimethamine and sulfadoxine (PSD or Fansidar) represents one of the most important chemotherapeutic agents currently used to treat falciparum malaria. To investigate the molecular basis of resistance to PSD, reliable in vitro drug assays are required to permit correlation of resistance levels with different genotypes. We describe here protocols that permit accurate evaluation of IC50 values for sulfadoxine (SDX) inhibition of Plasmodium falciparum. Historically, tests for this drug have suffered from poor reproducibility and extreme variability in reported values. We have examined a series of variables, including serum-containing versus serum-free media, erythrocyte source, pre-test growth conditions, test components and post-test processing. We define conditions which better control the levels of the drug antagonists folate and p-aminobenzoate, yielding reproducible differences between lines of P. falciparum with differing alleles of the dihydropteroate synthetase gene, which encodes the target enzyme of SDX. We also use this assay to demonstrate a marked difference in the response of different parasite lines to antagonism of SDX inhibition by exogenous folate. The ability to measure reliable IC50 values for SDX inhibition should greatly facilitate further experiments to explore the molecular basis of Fansidar resistance.
    Original languageEnglish
    Pages (from-to)223-230
    Number of pages7
    JournalParasitology
    Volume115
    Issue number3
    DOIs
    Publication statusPublished - 1997

    Keywords

    • Dihydropteroate synthetase
    • Fansidar resistance
    • Folate
    • Malaria
    • Plasmodium falciparum
    • Sulfadoxine

    Fingerprint

    Dive into the research topics of 'A modified in vitro sulfadoxine susceptibility assay for Plasmodium falciparum suitable for investigating Fansidar resistance'. Together they form a unique fingerprint.

    Cite this