FIG 6.
Rapid progression through trophozoite stage in artemisinin-resistant P. falciparum. The unusually rapid progression of artemisinin-resistant clones through the trophozoite stage was examined by quantifying the percentage of rings, trophozoites, and schizonts present throughout the asexual life cycle. The trophozoite prevalence data from two independent experiments then were fit to a polynomial function and, for comparison purposes, were plotted with time at 0 h as the peak of trophozoite prevalence. (A and B) Both of the artemisinin-resistant clones obviously progressed through the trophozoite stage at an accelerated rate compared to sensitive parasites (W2 and CB132). (C) Trophozoite prevalence data then were used to estimate the AUC(Troph h); both artemisinin-resistant clones had similar AUCs and spent approximately half the time that W2 and CB132 did in the trophozoite stage per asexual life cycle. CB132 is an artemisinin-sensitive isolate from Pailin, Cambodia, that was adapted to culture in 1992 (21).