Evaluation of Plasmodium vivax genotyping markers for molecular monitoring in clinical trials.
BACKGROUND
Many antimalarial interventions are accompanied by molecular monitoring of parasite infections, and a number of molecular typing techniques based on different polymorphic marker genes are used. Here, we describe a genotyping technique that provides a fast and precise approach to study Plasmodium vivax infection dynamics during circumstances in which individual clones must be followed over time. The method was tested with samples from an in vivo drug efficacy study.


METHODS
The sizes of polymerase chain reaction fragments were evaluated by capillary electrophoresis to determine the extent of size polymorphism for 9 potential genetic markers (5 genes of merozoite surface proteins [msp] and 4 microsatellites) in 93-108 P. vivax-positive blood samples from 3 villages in Papua New Guinea.


RESULTS
The microsatellites MS16 and Pv3.27 showed the greatest diversity in the study area, with 66 and 31 different alleles, respectively, followed by 2 fragments of msp1 and 2 other microsatellites. msp3alpha, msp4, and msp5 revealed limited polymorphism.


CONCLUSIONS
Even for the most diverse markers, the highest allelic frequencies reached 6% (MS16) or 13% (Pv3.27). To reduce the theoretical probability of superinfection with parasites that have the same haplotype as that detected at baseline, we propose to combine at least 2 markers for genotyping individual P. vivax infections.
Koepfli
Cristian
C
Swiss Tropical Institute, Basel, Switzerland.
Mueller
Ivo
I
Marfurt
Jutta
J
Goroti
Mary
M
Sie
Albert
A
Oa
Olive
O
Genton
Blaise
B
Beck
Hans-Peter
HP
Felger
Ingrid
I
D000483:Alleles; D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use*; D004351:Drug Resistance / Q000235:genetics; D005787:Gene Frequency; D005819:Genetic Markers; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D016780:Malaria, Vivax / Q000188:drug therapy / Q000453:epidemiology / Q000469:parasitology*; D018895:Microsatellite Repeats; D010219:Papua New Guinea / Q000453:epidemiology; D010966:Plasmodium vivax / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics
D000962:Antimalarials; D005819:Genetic Markers; D015800:Protozoan Proteins