Figure 2.

Human hepatocyte permissiveness to P. falciparum sporozoite infection depends on AQP9 expression. (A) Hepatocytes were transfected with sihRNAs and tested for their permissiveness to P. falciparum sporozoite infection: sihCD92-, sihCD81-, sihAQP9¹- and sihAQP3-transfected human hepatocytes were infected three days after transfection with P. falciparum sporozoites and cultured for 3 hours to evaluate sporozoite entry via double immunostaining for PfCSP protein (grey bars) or for four days to evaluate cell infection after immunolabelling of EEFs using HSP70 antibody (black bars). Sporozoite and EEF numbers are expressed as a percentage of those in sihCD92-transfected control hepatocytes. *p = 0.0006. (B) Hepatocytes overexpressing CD81 or AQP9 were tested for their permissiveness to P. falciparum infection: hepatocytes transduced with a lentiviral vector expressing GFP protein, as a control, hCD81, or hAQP9 were infected three days later with sporozoites and cultured for four days until EEF quantification. EEF numbers are expressed as a percentage of those in GFP-transduced control hepatocytes. The mean schizont numbers per well in controls of three independent experiments were 141, 203, and 314. *p = 0.05. (C) Hepatocytes were treated for the first two hours following sporozoite inoculation with three doses of phloretin. Hepatocytes were then washed and incubated with fresh complete medium for three additional days until EEF quantification. EEF rates are relative to those in untreated hepatocytes. *p = 0.0009. All analyses were carried out in triplicate wells, and the results are expressed as the mean ± standard deviation. p values were determined by Mann-Whitney U test.