IFN-γ production after inoculation with the Nc-Spain7 isolate. Concentrations of IFN-γ, in response to N. caninum soluble extract antigen, in lymphocyte culture supernatants of heifers intravenously challenged with 107 (IV1), 105 (IV2), 103 (IV3), and 102 (IV4) tachyzoites and the uninfected control group (A), and intravenously (IV2) and subcutaneously (SC) challenged heifers with 105 Nc-Spain7 tachyzoites and the uninfected control group (B). Each point represents the mean log IFN-γ concentration (pg/mL) + SD for each group from 0 to 4 wpi. Notice an enhanced IFN-γ production for IV1 (1 wpi (7 dpi)) and IV2 (2 wpi) groups compared to their basal pre-infection levels (A) and for the intravenous route (B). ****P < 0.0001.