Expression of PfRh4 in clinical isolates from PNG.

Notes: Results from immunofluorescence assays using blood smears of P. falciparum isolates from infected children. Isolates A–V were stained with DAPI and anti-PfRh4 antibody in order to investigate the rate of PfRh4 expression in clinical isolates. % Rh4 positive: proportion of DAPI-positive schizonts that were also PfRh4-positive. An arbitrary cut-off for positivity was set at 3 DAPI-positive schizonts that were also Rh4-positive. As a reference, schizonts of isolate 3D7 were stained with anti-PfRh4 antibody in 4 independent experiments to determine the average percentage of positive PfRh4 staining (mean 40.1%, range of 20.7%).