Validation of microsatellite markers for use in genotyping polyclonal Plasmodium falciparum infections.
Genotyping methods for Plasmodium falciparum drug efficacy trials have not been standardized and may fail to accurately distinguish recrudescence from new infection, especially in high transmission areas where polyclonal infections are common. We developed a simple method for genotyping using previously identified microsatellites and capillary electrophoresis, validated this method using mixtures of laboratory clones, and applied the method to field samples. Two microsatellite markers produced accurate results for single-clone but not polyclonal samples. Four other microsatellite markers were as sensitive as, and more specific than, commonly used genotyping techniques based on merozoite surface proteins 1 and 2. When applied to samples from 15 patients in Burkina Faso with recurrent parasitemia after treatment with sulphadoxine-pyrimethamine, the addition of these four microsatellite markers to msp1 and msp2 genotyping resulted in a reclassification of outcomes that strengthened the association between dhfr 59R, an anti-folate resistance mutation, and recrudescence (P = 0.31 versus P = 0.03). Four microsatellite markers performed well on polyclonal samples and may provide a valuable addition to genotyping for clinical drug efficacy studies in high transmission areas.
Greenhouse
Bryan
B
Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143, USA. bgreenhouse@medsfgh.ucsf.edu
Myrick
Alissa
A
Dokomajilar
Christian
C
Woo
Jonathan M
JM
Carlson
Elaine J
EJ
Rosenthal
Philip J
PJ
Dorsey
Grant
G
D000818:Animals; D005838:Genotype; D006801:Humans; D016778:Malaria, Falciparum / Q000145:classification* / Q000469:parasitology; D018895:Microsatellite Repeats; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics
D015800:Protozoan Proteins