Figure 6

Antibodies recognizing epitopes contained within the p19 of MSP-1p42 are responsible for inhibitory activity in immune serum. Antibodies from sera raised against MSP-1p42 of the 3D7 (FMP1) or FVO (FMP003) allele were purified using recombinant GST-MSP-1p19 either to 3D7 or the FVO allele and then tested for their functional activity. Cultures were set up at schizont stage in the presence of indicated antibody fractions (tested at the same titers as for the respective serum assays) and then incubated for 40 hrs. Invasion inhibition was measured by Syto-16 staining; growth/invasion inhibition was measured by HE-staining and subsequent flow cytometry against 3D7 (Panel A), FVO (Panel B) and CAMP/FUP (Panel C) parasites. Data are expressed as mean percentage of inhibition from three separate experiments (SEM). Asterisk indicates statistical difference of p < 0.01 (Student's T-test) between Syto-16 and HE.