Accumulation of CVIET Pfcrt allele of Plasmodium falciparum in placenta of pregnant women living in an urban area of Dakar, Senegal.
OBJECTIVE
Chemoprophylaxis is recommended during pregnancy to reduce the risk of placental infection. However, in areas with increasing drug resistance, it can trigger selection of resistant parasites in the placenta and increase the frequency of placental malaria. The objective of this study was to analyse the selection of drug-resistant parasites in the placenta in an area where chloroquine was still recommended as prophylaxis.


METHODS
We analysed the polymorphism of parasites from matched placental and venous blood samples at the time of delivery from women in Dakar. Polymorphism of the isolates was studied using nested PCR typing of MSA1 and MSA2 genes, and full sequence of PfCRT exon 2.


RESULTS
Of 692 women recruited at delivery, 72 had placental malaria. Two Pfcrt exon 2 genotypes were found, and 86% of the placentas had monoallelelic CVIET infection compared with 39% that had peripheral blood infection. Mixed parasite populations of CVIET/CVMNK occurred in 53% of the peripheral blood samples but only in 7% of the infected placentas. This selection of CVIET in placenta was not related to a decreased polymorphism of the parasites, as a large diversity of MSA1 and MSA2 was found in both placenta and venous blood. This diversity confirms that a multiplicity of circulation isolates can occur at low parasite transmission. msp1 and msp2 genotyping revealed mostly distinct populations of parasites in venous and placental blood.


CONCLUSIONS
These data suggest that, even in low transmission areas, diverse parasite populations can accumulate in the placenta during pregnancy despite strong selection at the PfCRT locus due to chemoprophylaxis with chloroquine.
Niang
Makhtar
M
Unité d'Immunologie, Institut Pasteur de Dakar, Sénégal.
Marrama
Laurence
L
Ekala
Marie Therese
MT
Alioune
Gaye
G
Tall
Adama
A
Ndiaye
Jean L
JL
Sarr
Demba
D
Dangou
Jean Marie
JM
Lehesran
Jean Y
JY
Bouchier
Christiane
C
Mercereau-Puijalon
Odile
O
Jambou
Ronan
R
D000293:Adolescent; D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics; D001769:Blood / Q000469:parasitology; D018890:Chemoprevention / Q000379:methods; D002648:Child; D002738:Chloroquine / Q000627:therapeutic use; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004351:Drug Resistance; D005260:Female; D005787:Gene Frequency; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology*; D026901:Membrane Transport Proteins / Q000235:genetics*; D020066:Merozoite Surface Protein 1 / Q000235:genetics; D010920:Placenta / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D037841:Pregnant People; D015800:Protozoan Proteins / Q000235:genetics*; D012675:Senegal / Q000453:epidemiology; D017422:Sequence Analysis, DNA
D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D026901:Membrane Transport Proteins; D020066:Merozoite Surface Protein 1; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium; D002738:Chloroquine