FIG. 4.

Proliferation of wild-type and of Δgra2 mutant parasites in vitro. (A) The wild type, mutant, and complemented clone showed similar levels of [³H]uracil incorporation at 24, 72, and 120 h after inoculation of HFF cells. Monolayers were challenged with 2 × 10⁶, 2 × 10⁴, and 5 × 10³ parasites, pulsed with [³H]uracil for the final 24 h, and harvested at 24, 72, and 120 h, respectively. (B) Growth in macrophages as determined by counting the average number of parasites per vacuole at 20 or 40 h postinoculation. Similar growth rates were observed for the wild type, mutant, and complemented clone in normal macrophages, while activated macrophages suppressed their growth to similar extents.