Parasite invasion of erythrocytes in vivo. (A) Parasite growth in vivo. Parasitemia in groups of 6 mice infected on day 0 with 1000 or 100 WT or MSP7ko parasites. The course of parasitemia was observed for 12 days. (B) Ratio of the percentage parasitemia in normocytes and reticulocytes for WT and MSP-7Ko parasites during the course of an infection initiated with 1000 parasites. (C) Giemsa-stained blood smear from infections with WT or MSP7ko parasites at days 7, 10, and 12 after infection. Infected reticulocyte, infected normocyte (mature RBC), and uninfected normocyte are indicated by arrow, single arrowhead, and double arrowheads, respectively.