Figure 3

Immunofluorescence microscopy showing co-localisation of PfMSA180 with MSP-1 within mature schizonts. (a) Immunofluorescence detection of antibodies to C1 (N-terminus of PfMSA180) showing areas of co-localisation with MSP1 antibodies. Upper panel C1-PfMSA180 (Red), MSP1 (Green). Second panel C1-PfMSA180 (Green), Exp1 (Red). (b) Immunofluorescence detection of antibodies to C3 (C-terminus of PfMSA180) showing areas of co-localisation with MSP1 antibodies. Upper panel C3-PfMSA180 (Red), MSP1 (Green). Second panel C3-PfMSA180 (Green), Exp1 (Red). MSP1 is a merozoite surface protein and Exp1 (Exportin 1) is a parasitophorous vacuole membrane marker protein. The first column shows DAPI (4′,6-diamidino-2-phenylindole) DNA-stained schizonts, the second column shows the staining observed with marker antibodies, the third column displays PfMSA180 antibody staining, the fourth column is a merged image of the antibody staining, and the fifth column shows the transmitted image (TD) together with DAPI staining. The last column is the graph for antibody staining to represent Pearson’s correlation coefficient for co-localisation. The correlation coefficient is a measure of signal intensities of the two fluorophores in one image and the magnitude of the coefficient predicts the spatial relationship of the two fluorophores. A value close to zero indicates no correlation between the two fluorophores, while a value close to 1 indicates a positive correlation between the two fluorophores⁴². Five images were captured for each antibody combination and correlation coefficient values for colocalisation of anti-MSA180 (C1, C3) with anti-MSP1 ranged from 0.75–0.79, while the correlation coefficient of anti-MSA180 (C1, C3) with anti-Exp1 ranged from 0.56–0.60. One image for each antibody combination is displayed here.