FIG. 1.
L. donovani amastigotes downregulate IFN-γ-induced gene expression. Adherent BMMs were infected with freshly isolated L. donovani amastigotes for 18 h at a parasite-to-cell ratio of 20:1 and then stimulated with 100 U/ml IFN-γ for the indicated times. Total RNA was extracted, reverse transcribed, and analyzed by RT-PCR (A) or RT-qPCR (B) with primers specific for I-Aα, iNOS, and HPRT, as described in Materials and Methods. (A) Band intensities were quantified by densitometric analysis and normalized to those of the HPRT housekeeping gene; (B) the level of gene expression was normalized to that of HPRT and calculated via the 2−ΔΔCT method. Values are expressed as the fold difference from the results for the uninfected, unstimulated cells and represent the means ± SDs of three independent experiments (A) or of qPCR triplicates of an experiment representative of two others (B). *, P < 0.05; **, P < 0.02.