Figure 2. Purified PS^POS promastigotes are required for the in vitro infectivity of PS^NEG forms.

(A) Rates of internalization (2 h p. i.) and of intracellular proliferation (72 h p. i.) of magnetic purified PS^NEG and PS^POS metacyclic promastigotes measured by their infectivity index in macrophage cultures. (B) Inhibition of NO synthesis by PS^POS and PS^NEG populations. Macrophages activated with IFNγ and LPS were infected with magnetic purified PS^NEG or PS^POS metacyclic promastigotes. After 48 h of infection, NO production by cultured macrophages were quantified by Griess reaction in the supernatants. Figure displays one experiment out of three with similar results. *p<0.001, **p<0.05.