NGF and infection: NGF secreted in response to T cruzi infection is bioactive because 1) conditioned medium (CoM) obtained from T cruzi-infected primary CFs at 72 h post-infection (PI), but not medium from uninfected cells (0-h CoM) strongly promotes neurite outgrowth in PC12 cells (Fig. 3C, left panels) in a time-of-infection dependent manner (Fig. 2C, left bar graph), and 2) an NGF anti-serum blocks the neurite-enhancement effect of active CoM nearly completely (Fig. 3C, right panels and bar graph).