Diminished capacity of long-term cultured <i>L. infantum</i> promastigotes to differentiate and proliferate as axenic amastigotes.

<p>CFSE-labeled non-purified promastigotes submitted to 4, 21 or 31 successive <i>in vitro</i> passages or from a field recovered naturally attenuated strain (Aten) were cultured in MAA20 for 3 days to induce differentiation into the amastigote form. (<b>A</b>) Parasite multiplication was followed by FACScalibur quantification of CFSE fluorescence. (<b>B</b>) For each time, the mean fluorescence intensity (MFI) was calculated. The mean and standard deviation are shown. **<i>P</i><0,01; ***<i>P</i><0,001 (<b>C</b>) At the same time, parasite viability was followed by propidium iodide (PI) incorporation.