Common origin and fixation of Plasmodium falciparum dhfr and dhps mutations associated with sulfadoxine-pyrimethamine resistance in a low-transmission area in South America

Andrea M. McCollum, Kristen Mueller, Leopoldo Villegas, Venkatachalam Udhayakumar, Ananias A. Escalante

Research output: Contribution to journalArticle

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Abstract

Recent studies indicated that sensitive parasites could increase in frequency in a population when drugs are removed, suggesting that the life span of affordable antimalarial drugs could be expanded. We studied 97 samples from Bolivar State, Venezuela, an area where sulfadoxine-pyrimethamine (SP) has not been used for 8 years due to its ineffectiveness. We characterized point mutations in two genes that have been implicated in resistance to SP, dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps). We also assayed neutral microsatellite markers around the dhfr (chromosome 4) and dhps (chromosome 8) genes and on chromosomes 2 and 3 to track the origin and spread of resistant alleles. We found that drug-resistant SP mutants are fixed in the population. Two genotypes were present in the samples, dhfr(50R/51I/108N) dhps(437G/540E/581G) (90.7%) and dhfr(51I/108N) dhps(437G/581G) (9.3%). We show a single microsatellite haplotype for all of the dhfr and dhps alleles, and the alleles at the microsatellite loci are different from those present in Africa. Thus, in these samples from Venezuela, there is a single origin for both dhfr and dhps SP-resistant alleles, and these alleles originated independently of those characterized from Africa. Furthermore, this is the first report of a "hitchhiking effect" on the genetic variation around dhps due to selection by SP using an extensive set of microsatellite markers. Our results indicate that, in areas where there is limited gene flow, the fixation of drug-resistant parasites in the population is stable, even after drug selection is relaxed.

Original languageEnglish (US)
Pages (from-to)2085-2091
Number of pages7
JournalAntimicrobial Agents and Chemotherapy
Volume51
Issue number6
DOIs
StatePublished - Jun 2007

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Tetrahydrofolate Dehydrogenase
South America
Plasmodium falciparum
Microsatellite Repeats
Alleles
Mutation
Venezuela
Pharmaceutical Preparations
Parasites
Dihydropteroate Synthase
Chromosomes, Human, Pair 8
Chromosomes, Human, Pair 4
Chromosomes, Human, Pair 3
Chromosomes, Human, Pair 2
Gene Flow
Antimalarials
Population Dynamics
Point Mutation
Haplotypes
Population

ASJC Scopus subject areas

  • Pharmacology (medical)

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Common origin and fixation of Plasmodium falciparum dhfr and dhps mutations associated with sulfadoxine-pyrimethamine resistance in a low-transmission area in South America. / McCollum, Andrea M.; Mueller, Kristen; Villegas, Leopoldo; Udhayakumar, Venkatachalam; Escalante, Ananias A.

In: Antimicrobial Agents and Chemotherapy, Vol. 51, No. 6, 06.2007, p. 2085-2091.

Research output: Contribution to journalArticle

McCollum, Andrea M. ; Mueller, Kristen ; Villegas, Leopoldo ; Udhayakumar, Venkatachalam ; Escalante, Ananias A. / Common origin and fixation of Plasmodium falciparum dhfr and dhps mutations associated with sulfadoxine-pyrimethamine resistance in a low-transmission area in South America. In: Antimicrobial Agents and Chemotherapy. 2007 ; Vol. 51, No. 6. pp. 2085-2091.
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