Fig. 2

Conditional knockdown of PfSWIB interferes with the growth and development of parasite. a Growth curve analysis (GCA) during 96-h in vitro culturing. Data are presented as the rate of parasitemia (%) in the four parasite lines, PfSWIB^sh+, PfSWIB^sh−, 3D7^sh+ and 3D7^sh−. All parasite lines were initially synchronized into 0–6 h ring-stage parasites, with exactly the same preliminary parasitemia of 0.2%. Data were collected every 12 h up to 96 h. The survival curves are drawn using GraphPad Prism® (version 5.0). The error bars represent the mean ± SD of three independent experiments determined by counting the rate of parasitemia. Key: sh+, parasite lines cultured in the presence of shield1 (1:2000); sh−, lines cultured in the absence of shield1. The rate of parasitemia (%) of different lines were compared statistically by a one-way ANOVA followed by Bonferroniʼs multiple comparison post-hoc tests (*P < 0.05, **P < 0.01). b Western blot assay of PfSWIB fusion protein levels in three lines at the ring and trophozoite-stages within the third life-cycle of P. falciparum. An antibody to aldolase (Roche) was used as a positive control. Rabbit anti-HA (Abcam) was used to identify fusion PfSWIB proteins in different lines. Key: +, parasite lines cultured in the presence of shield1; −, lines cultured in the absence of shield1. Significance and different expression of PfSWIB fusion protein were calculated by the gray-level image analysis using ImageJ software. The error bars represent the mean ± SD of two independent western blot experiments. ‘R’ and ‘T’ denote the ring and trophozoite stage of P. falciparum, respectively. Statistical significance was determined with the two-tailed Student’s t-test (*P < 0.05, **P < 0.01)