PfSUB2 Redistributes to the Free Merozoite Posterior in an Actin-Dependent Manner

<div><p>(A) IFA images of free merozoites of PfSUB2HA clone 2D dual-labelled with mAb 61.3 (anti-RhopH2) and either mAb 3F10 (anti-HA) or 4G2 (anti-AMA1). The anti-HA signal formed either a single punctate signal at the extreme posterior of the merozoite (top), or twin foci lateral to its anterior–posterior axis (middle). Identical results were obtained using PfSUB2HA clone 10E, or using anti-RAP2 mAb H5 as the rhoptry marker (not shown).</p><p>(B) Latrunculin inhibits rearward translocation of PfSUB2. Merozoites of PfSUB2HA clone 2D released into medium containing 1% (v/v) DMSO only (solvent control), or 5 μM latrunculin A (Latrunc), or 4 μM cytochalasin D (Cyt D), probed as above with mAb 61.3 (anti-RhopH2) and mAb 3F10 (anti-HA). Note that neither compound had any effect on the efficiency of schizont rupture and merozoite release, nor on AMA1 relocalisation, but both blocked erythrocyte invasion by more than 95% at the concentrations used (not shown).</p><p>(C) PfSUB2 remains at the plasma membrane of the newly invaded parasite. Ring stages of PfSUB2HA clone 2D (≤2 h post-invasion) probed with anti-MSP1 mAb 1E1 and anti-HA mAb 3F10. Parasite nuclei are stained throughout with DAPI (blue). Scale bar represents 2 μm.</p>