Is the Resistance Transporter Gene pfcrt Linked with Susceptibility of Plasmodium falciparum to Chloroquine?

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Wanna Chaijaroenkul
Stephen A Ward
Mathirut Mungthin
Andrew Owen
Patrick G Bray
David Jhonson
Kesara Na Bangchang

Abstract

Recent studies have definitively demonstrated a link between mutations in the gene
pfcrt and resistance to the antimalarial chloroquine (CQ) in Plasmodium falciparum.
Although these mutations are predictive of CQ resistance they are not quantitatively
predictive of the degree of resistance. We had undertaken analysis of a total of 95 recently
adapted P. falciparum isolates from Thailand. Parasites had been characterized for their drug
susceptibility phenotypes and genotypes with respect to pfcrt. From the original 95 isolates,
20 were selected for complete pfcrt sequence analysis. Almost all of the parasites
characterized carried the previously reported mutations K76T, A220S, Q271E, N326S, I356T
and R371I. On complete sequencing, isolates were identified with novel mutations at K76A
and E198K. The isolates carrying E198K were less resistant to CQ than those that were not.
Data from the present study suggested that other genes may also contribute to the degree of
resistance once the resistance phenotype is established through mutations in pfcrt gene.

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2010 Annual Meeting Abstracts/Lectures