title: Genetic polymorphism of merozoite surface protein 2 and prevalence of K76T pfcrt mutation in Plasmodium falciparum field isolates from Congolese children with asymptomatic infections.
abstract: BACKGROUND
  In order to prepare the field site for future interventions, the prevalence of asymptomatic Plasmodium falciparum infection was evaluated in a cohort of children living in Brazzaville. Plasmodium falciparum merozoite surface protein 2 gene (msp2) was used to characterize the genetic diversity and the multiplicity of infection. The prevalence of mutant P. falciparum chloroquine resistance transporter (pfcrt) allele in isolates was also determined.
  
  
  METHODS
  Between April and June 2010, 313 children below 10 years of age enrolled in the cohort for malaria surveillance were screened for P. falciparum infection using microscopy and polymerase chain reaction (PCR). The children were selected on the basis of being asymptomatic. Plasmodium falciparum msp2 gene was genotyped by allele-specific nested PCR and the pfcrt K76T mutation was detected using nested PCR followed by restriction endonuclease digestion.
  
  
  RESULTS
  The prevalence of asymptomatic P. falciparum infections was 8.6% and 16% by microscopy and by PCR respectively. Allele typing of the msp2 gene detected 55% and 45% of 3D7 and FC27 allelic families respectively. The overall multiplicity of infections (MOI) was 1.3. A positive correlation between parasite density and multiplicity of infection was found. The prevalence of the mutant pfcrt allele (T76) in the isolates was 92%.
  
  
  CONCLUSIONS
  This is the first molecular characterization of P. falciparum field isolates in Congolese children, four years after changing the malaria treatment policy from chloroquine (CQ) to artemisinin-based combination therapy (ACT). The low prevalence of asymptomatic infections and MOI is discussed in the light of similar studies conducted in Central Africa.
authors.affiliation: Congolese Foundation for Medical Research, Brazzaville, Republic of Congo.
authors.forename: Felix
authors.initials: F
authors.lastname: Koukouikila-Koussounda
authors.forename: Vladimir
authors.initials: V
authors.lastname: Malonga
authors.forename: Pembe Issamou
authors.initials: PI
authors.lastname: Mayengue
authors.forename: Mathieu
authors.initials: M
authors.lastname: Ndounga
authors.forename: Christevy Jeannhey
authors.initials: CJ
authors.lastname: Vouvoungui
authors.forename: Francine
authors.initials: F
authors.lastname: Ntoumi
mesh_terms: D000953:Antigens, Protozoan / Q000235:genetics*; D058345:Asymptomatic Infections; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003223:Congo; D016054:DNA, Protozoan / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000469:parasitology* / Q000473:pathology; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D008853:Microscopy; D020125:Mutation, Missense; D018512:Parasitemia / Q000175:diagnosis / Q000469:parasitology; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D015800:Protozoan Proteins / Q000235:genetics*
chemical_list: D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium