Progressive increase in point mutations associated with chloroquine resistance in Plasmodium falciparum isolates from India.
BACKGROUND
Effective malaria control programs require continuous monitoring of drug pressure in the field, using molecular markers.


METHODS
We used sequence analysis to investigate the pfcrt and pfmdr1 mutations in Indian Plasmodium falciparum isolates. To evaluate the chloroquine drug pressure in the field, isolates were collected from 5 different areas at 2 time points, with an interval of 2 years.


RESULTS
In 265 P. falciparum isolates, pfcrt mutations were observed at codons 72, 74, 75, 76, and 220, resulting in 8 different genotypes: SMNTS (61.89%), CIETS (12.08%), CMNKS (0.38%), CMNTA (2.64%), CMNTS (4.91%), SMNTA (0.38%), CIDTS (2.26%), and wild-type CMNKA (15.47%). During the 2-year period, there was a significant decrease in the number of isolates with the SMNTS genotype and an increase in the number of isolates with the highly chloroquine-resistant pfcrt genotype CIETS (P < .05). The N86Y mutation was less prevalent (30.13%) than the Y184F mutation (99.16%) in the pfmdr1 gene in 239 isolates, but the number of isolates with the N86Y mutation increased significantly during the 2-year period (P < .05). The number of isolates with higher total numbers of pfcrt and pfmdr1 2-loci mutations, therefore, increased significantly during this period. There was a regional bias in the mutation rate of these genes, because isolates from areas where chloroquine resistance was high had higher numbers of 2-loci mutations, and areas where chloroquine resistance was low had isolates with lower numbers of 2-loci mutations.


CONCLUSIONS
There was a temporal increase in the number of pfcrt and pfmdr1 2-loci mutations, and this led to the higher level of chloroquine resistance. This is a cause for concern for the antimalarial drug policy in India.
Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.
Pooja
P
Mittra
Sumiti
S
Vinayak
Hina
H
Chandawat
Manoj K
MK
Das
Neeru
N
Singh
Sukla
S
Biswas
Vas
V
Dev
Ashwani
A
Kumar
Musharraf A
MA
Ansari
Yagya D
YD
Sharma
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology*; D003140:Communicable Disease Control; D004252:DNA Mutational Analysis; D016054:DNA, Protozoan / Q000032:analysis / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D006801:Humans; D007194:India; D016778:Malaria, Falciparum / Q000469:parasitology*; D008565:Membrane Proteins / Q000235:genetics*; D026901:Membrane Transport Proteins; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D017354:Point Mutation; D015800:Protozoan Proteins / Q000235:genetics*
D018528:ATP-Binding Cassette Transporters; D000962:Antimalarials; D016054:DNA, Protozoan; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C059987:mdr gene protein, Plasmodium; D002738:Chloroquine