title: Evidence of selective sweeps in genes conferring resistance to chloroquine and pyrimethamine in Plasmodium falciparum isolates in India.
abstract: Treatment of Plasmodium falciparum is complicated by the emergence and spread of parasite resistance to many of the first-line drugs used to treat malaria. Antimalarial drug resistance has been associated with specific point mutations in several genes, suggesting that these single nucleotide polymorphisms can be useful in tracking the emergence of drug resistance. In India, P. falciparum infection can manifest itself as asymptomatic, mild, or severe malaria, with or without cerebral involvement. We tested whether chloroquine- and antifolate drug-resistant genotypes would be more commonly associated with cases of cerebral malaria than with cases of mild malaria in the province of Jabalpur, India, by genotyping the dhps, dhfr, pfmdr-1, and pfcrt genes using pyrosequencing, direct sequencing, and real-time PCR. Further, we used microsatellites surrounding the genes to determine the origins and spread of the drug-resistant genotypes in this area. Resistance to chloroquine was essentially fixed, with 95% of the isolates harboring the pfcrt K76T mutation. Resistant genotypes of dhfr, dhps, and pfmdr-1 were found in 94%, 17%, and 77% of the isolates, respectively. Drug-resistant genotypes were equally likely to be associated with cerebral malaria as with mild malaria. We found evidence of a selective sweep in pfcrt and, to a lesser degree, in dhfr, indicating high levels of resistance to chloroquine and evolving resistance to pyrimethamine. Microsatellites surrounding pfcrt indicate that the resistant genotypes (SVMNT) were most similar to those found in Papua New Guinea.
authors.affiliation: Malaria Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, 4770 Buford Highway, MS F-12, Chamblee, GA 30341, USA. zdy0@cdc.gov
authors.forename: Tonya
authors.initials: T
authors.lastname: Mixson-Hayden
authors.forename: Vidhan
authors.initials: V
authors.lastname: Jain
authors.forename: Andrea M
authors.initials: AM
authors.lastname: McCollum
authors.forename: Amanda
authors.initials: A
authors.lastname: Poe
authors.forename: Avinash C
authors.initials: AC
authors.lastname: Nagpal
authors.forename: Aditya P
authors.initials: AP
authors.lastname: Dash
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Stiles
authors.forename: Venkatachalam
authors.initials: V
authors.lastname: Udhayakumar
authors.forename: Neeru
authors.initials: N
authors.lastname: Singh
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics*; D017125:Genes, Protozoan; D005838:Genotype; D006801:Humans; D007194:India; D016779:Malaria, Cerebral / Q000469:parasitology; D016778:Malaria, Falciparum / Q000469:parasitology; D018895:Microsatellite Repeats / Q000235:genetics; D021261:Parasitic Sensitivity Tests; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D017354:Point Mutation; D015800:Protozoan Proteins / Q000235:genetics*; D011739:Pyrimethamine / Q000494:pharmacology*; D017422:Sequence Analysis, DNA
chemical_list: D000962:Antimalarials; D015800:Protozoan Proteins; D002738:Chloroquine; D011739:Pyrimethamine