Gel versus capillary electrophoresis genotyping for categorizing treatment outcomes in two anti-malarial trials in Uganda.
BACKGROUND
Molecular genotyping is performed in anti-malarial trials to determine whether recurrent parasitaemia after therapy represents a recrudescence (treatment failure) or new infection. The use of capillary instead of agarose gel electrophoresis for genotyping offers technical advantages, but it is unclear whether capillary electrophoresis will result in improved classification of anti-malarial treatment outcomes.


METHODS
Samples were genotyped using both gel and capillary electrophoresis from randomized trials of artemether-lumefantrine (AL) vs. dihydroartemisinin-piperaquine (DP) performed in two areas of Uganda: Kanungu, where transmission is moderate, and Apac, where transmission is very high. Both gel and capillary methods evaluated polymorphic regions of the merozoite surface protein 1 and 2 and glutamine rich protein genes.


RESULTS
Capillary electrophoresis detected more alleles and provided higher discriminatory power than agarose gel electrophoresis at both study sites. There was only moderate agreement between classification of outcomes with the two methods in Kanungu (kappa = 0.66) and poor agreement in Apac (kappa = 0.24). Overall efficacy results were similar when using gel vs. capillary methods in Kanungu (42-day risk of treatment failure for AL: 6.9% vs. 5.5%, p = 0.4; DP 2.4% vs. 2.9%, p = 0.5). However, the measured risk of recrudescence was significantly higher when using gel vs. capillary electrophoresis in Apac (risk of treatment failure for AL: 17.0% vs. 10.7%, p = 0.02; DP: 8.5% vs. 3.4%, p = 0.03). Risk differences between AL and DP were not significantly different whether gel or capillary methods were used.


CONCLUSIONS
Genotyping with gel electrophoresis overestimates the risk of recrudescence in anti-malarial trials performed in areas of high transmission intensity. Capillary electrophoresis provides more accurate outcomes for such trials and should be performed when possible. In areas of moderate transmission, gel electrophoresis appears adequate to estimate comparative risks of treatment failure.
Gupta
Vinay
V
Department of Medicine, University of California, San Francisco, CA 94143, USA.
Dorsey
Grant
G
Hubbard
Alan E
AE
Rosenthal
Philip J
PJ
Greenhouse
Bryan
B
D000818:Animals; D000962:Antimalarials / Q000627:therapeutic use*; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D016054:DNA, Protozoan / Q000235:genetics; D004338:Drug Combinations; D004359:Drug Therapy, Combination; D004587:Electrophoresis, Agar Gel; D019075:Electrophoresis, Capillary; D004983:Ethanolamines; D005449:Fluorenes; D005838:Genotype; D006801:Humans; D007223:Infant; D010961:Plasmodium / Q000145:classification / Q000187:drug effects* / Q000235:genetics*; D011804:Quinolines / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D014454:Uganda; D010879:Piperazines
D000962:Antimalarials; D000077611:Artemether, Lumefantrine Drug Combination; D037621:Artemisinins; D016054:DNA, Protozoan; D004338:Drug Combinations; D004983:Ethanolamines; D005449:Fluorenes; D011804:Quinolines; C039060:artenimol; C034759:piperaquine; D010879:Piperazines