Ookinete microneme secretion was analyzed as previously reported (47 (link)). Briefly, about 2.0 × 106 of ookinetes were purified from in vitro culture using the LS magnetic column (#130-042-401, Miltenyi Biotec) and incubated in 500 μl of PBS for 4 hours at 22°C. The cells were spun down at 750g, and the supernatant was collected, filtered through a filter (0.45 μm; SLHP033RS, Millipore), and subjected to Western blot assay.