FIGURE 4.

Promastigote growth and metacyclogenesis of the L. major LmNTR heterozygous line. A, L. major wild type (square; solid line) and LmNTR^+/−BLA heterozygote (circle; dotted line) promastigote parasite growth was monitored until cultures were in the stationary phase of growth (time = 240 h). At 120 h onward, the number of metacyclic form parasites in wild type (triangle; solid line) and LmNTR^+/−BLA heterozygote (cross; dotted line) promastigote culture was determined following purification by agglutination. The data are expressed as % metacyclic load in the total L. major population. All curves shown are derived from a single data set and are representative of experiments performed in triplicate. B, dose-response curves of nifurtimox on L. major wild type (wt) and LmNTR^+/−BLA heterozygote (NTR^+/−) promastigotes. Data are means from four experiments ± S.D., and the differences in susceptibility were statistically significant (p < 0.01), as assessed by Student's t test.