Figure 2.

Asexual Blood Stage Parasite Morphology in FRGN KO huHep Mice

(A) Mice were infected with P. vivax sporozoites, and parasites were transitioned to blood stages following the protocol described in Figure 1A. Giemsa-stained thin blood smears were analyzed at various time points between day 9 (5 h after the first reticulocyte injection) and day 12 post infection. All asexual parasite forms were seen, and the morphology was comparable with parasites seen on blood smears from P. vivax-infected patients. Scale bars represent 5 μm.

(B) Host cells infected with parasites at different developmental stages, including early ring stages 4 h after the first reticulocyte infection and mature schizonts, were analyzed for the presence of Schüffner's dots. None of the early ring stage-infected reticulocytes showed any Schüffner's dots, whereas these were observed on all trophozoite and schizont-infected cells.

(C) IFAs were performed on thin blood smears from day 12 post infection and stained with anti-MSP1 and DAPI. Intact MSP1 staining of fully segmented schizonts could be observed. Scale bars represent 5 μm.

(D) Thin blood smears from two individual experiments were stained with anti-MSP1 and DAPI. The quantity of merozoites per schizont was counted. On average, 6.5 merozoites per schizont were detected. Each dot represents one schizont. Mean ± SD is shown.

(E) IFAs were performed on thin blood smears from day 14 post infection and stained with anti-MSP1 and DAPI. Free merozoites as well as invaded ring stage parasites were observed. Scale bars represent 5 μm.