Fig. 4

Reactivity of vaccine-induced antisera with the native PSOP25 antigen in ookinetes. a IFA was performed on ookinete using serum after VLP-PSOP25 (PolyAb). Positive control: serum after rPSOP25 + alum; negative control: a control mouse serum (PBS). All parasites were co-stained with antibodies against the marker for the ookinetes stage (Pbs25, red). Nuclei were stained with DAPI (blue). Scale bar = 5 μm. b Western blot analysis of purified P. berghei ookinete (Ook) lysates with serum after VLP-PSOP25 (PolyAb). The lysates at 30 μg per lane were subjected to electrophoresis under reducing conditions by 10% SDS-PAGE and probed with the corresponding antisera. Serum after rPSOP25 + alum was used as positive control; a control mouse serum (PBS) was used as a negative control. The arrows indicated the expected ~ 40-kDa band