title: In vitro growth of Plasmodium falciparum in neonatal blood.
abstract: BACKGROUND
  Children below the age of six months suffer less often from malaria than older children in sub-Saharan Africa. This observation is commonly attributed to the persistence of foetal haemoglobin (HbF), which is considered not to permit growth of Plasmodium falciparum and therefore providing protection against malaria. Since this concept has recently been challenged, this study evaluated the effect of HbF erythrocytes and maternal plasma on in vitro parasite growth of P. falciparum in Central African Gabon.
  
  
  METHODS
  Umbilical cord blood and peripheral maternal blood were collected at delivery at the Albert Schweitzer Hospital in Gabon. Respective erythrocyte suspension and plasma were used in parallel for in vitro culture. In vitro growth rates were compared between cultures supplemented with either maternal or cord erythrocytes. Plasma of maternal blood and cord blood was evaluated. Parasite growth rates were assessed by the standard HRP2-assay evaluating the increase of HRP2 concentration in Plasmodium culture.
  
  
  RESULTS
  Culture of P. falciparum using foetal erythrocytes led to comparable growth rates (mean growth rate = 4.2, 95% CI: 3.5 - 5.0) as cultures with maternal red blood cells (mean growth rate =4.2, 95% CI: 3.4 - 5.0) and those from non-malaria exposed individuals (mean growth rate = 4.6, 95% CI: 3.8 - 5.5). Standard in vitro culture of P. falciparum supplemented with either maternal or foetal plasma showed both significantly lower growth rates than a positive control using non-malaria exposed donor plasma.
  
  
  CONCLUSIONS
  These data challenge the concept of HbF serving as intrinsic inhibitor of P. falciparum growth in the first months of life. Erythrocytes containing HbF are equally permissive to P. falciparum growth in vitro. However, addition of maternal and cord plasma led to reduced in vitro growth which may translate to protection against clinical disease or show synergistic effects with HbF in vivo. Further studies are needed to elucidate the pathophysiology of innate and acquired protection against neonatal malaria.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sauerzopf
authors.forename: Yabo J
authors.initials: YJ
authors.lastname: Honkpehedji
authors.forename: Ayôla A
authors.initials: AA
authors.lastname: Adgenika
authors.forename: Elianne N
authors.initials: EN
authors.lastname: Feugap
authors.forename: Ghyslain Mombo
authors.initials: GM
authors.lastname: Ngoma
authors.forename: Jean-Rodolphe
authors.initials: JR
authors.lastname: Mackanga
authors.forename: Felix
authors.initials: F
authors.lastname: Lötsch
authors.forename: Marguerite M
authors.initials: MM
authors.lastname: Loembe
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kremsner
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mordmüller
authors.affiliation: Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, Vienna, Austria. michael.ramharter@medizin.uni-tuebingen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Ramharter
mesh_terms: D000293:Adolescent; D000328:Adult; D000953:Antigens, Protozoan / Q000032:analysis; D001769:Blood / Q000276:immunology / Q000469:parasitology*; D005260:Female; D005681:Gabon; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010963:Plasmodium falciparum / Q000254:growth & development* / Q000276:immunology; D011247:Pregnancy; D015800:Protozoan Proteins / Q000032:analysis; D055815:Young Adult
chemical_list: D000953:Antigens, Protozoan; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins