<p>) Parasite burden in the spleens of hamsters (n = 6 per group) infected with <i>L. donovani</i> for 14, 28, 42, and 56 days. The mean and SEM (error bars) of the parasite burden, determined by luminometry and interpolation from an amastigote standard curve, is shown from a single experiment that is representative of 2 independent experiments. <b>B</b>) Arginase activity in the serum (open bars) and spleen tissue (filled bars) of uninfected hamsters (Day 0) and hamsters infected with <i>L. donovani</i> (n = 6 per group) for 7, 14, 28, 42, and 56 days. The mean and SD of the tissue arginase activity, determined by assay of urea production, is shown. <b>C</b>) Hamster arg1 protein expression determined by western blot in spleens of control hamsters (0 days post-infection) and hamsters infected with <i>L. donovani</i> for 7, 14, and 28 days. The expression of GAPDH is shown as a control for protein loading. Each lane contains splenic lysate from a single hamster, with two lanes per time point. The anti-arginase antibody did not react with parasite arginase by immunoblot. <b>D</b>) Time course of expression of hamster arg1 mRNA (filled bars), <i>L. donovani</i> arginase mRNA (empty bars), hamster NOS2 (iNOS) mRNA (hatched bars), and hamster arg2 mRNA (hatched bars) in spleens of control hamsters (0 days post-infection) and hamsters infected with <i>L. donovani</i> for 7, 14, 28, 42, and 56 days. The mean and standard deviation (error bars) of the fold-increase of arginase mRNA relative to BHK cells, determined by real time RT-PCR in groups of 6 animals, is shown from a single experiment that is representative of 3 independent experiments. The statistical significance of differences in each of the panels is identified by asterisks (*, p<0.05; **, p<0.01; ***, p<0.001).</p
