FIG. 8.
Parasite-specific antibodies in the serum of chronically infected mice subjected to different parasite loads at the acute phase of T. cruzi infection. Mice were infected with 103 (low dose) or 105 (high dose) parasites and treated at day 6 with benznidazole. One year after infection, mice were bled and their sera were analyzed by ELISA to determine the levels of specific IgM (A), IgG1 (B), and IgG2a (C) antibodies. Concentrations (micrograms per milliliter) of specific IgG1 and IgG2a were calculated from standard curves as described in Materials and Methods. Levels of specific IgM are expressed as OD of serum samples diluted 1/800. Each bar represents the mean ± standard error of individual values from 10 or 11 mice. ∗, P < 0.05 compared with the control group; ∗∗, P < 0.05 compared with the control and the low-dose group.