Subcellular distribution of PfEMMA1 in merozoites and infected RBCs. (A–H) Merozoites (Pf3D7) that were live, non-permeabilized (A–D), or permea-bilized (E–H) were probed with antibodies against PfEMMA1 fragment 2 (A–C and E–G), and labeling of PfEMMA1 is shown. No proteins were detected with preimmune serum (D and H). A merozoite is in contact with an uninfected RBC at its apex where PfEMMA1 is highly expressed (E). (I–L) A live, non-permeabilized Pf3D7 schizont (I) and merozoite (J) were compared with a permeabilized schizont (K) and merozoite (L); cells were probed with anti-PfEMMA1 C-terminus antibodies (I–L). Staining of PfEMMA1 was observed only in permeabilized iRBCs (K) and merozoites (L). Counterstains included DAPI, PfAMA1, PfMSP1 and →4, PfRH5, and anti-GPC. DIC, differential interference contrast microscopy. Scale bars, 2 μm (A–D, F–H, J, and L) or 5 μm(E, I, and K).

Michelow IC, Park S, Tsai SW, Rayta B, Pasaje CFA, Nelson S, Early AM, FroschAP, Ayodo G, Raj DK, Nixon CE, Nixon CP, Pond-Tor S, Friedman JF, Fried M, Duffy PE, Le Roch KG, Niles JC, Kurtis JD. A newly characterized malaria antigen on erythrocyte and merozoite surfaces induces parasite inhibitory antibodies. J Exp Med. 2021 218(9):e20200170.

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