IL10 and infection: In contrast, mice infected intravenously with P15 had significantly higher levels of the cytokines IL-4 (p = 0.0039), IL-10 (p = 0.017) and TNF-α (p = 0.01) in the brain at day 7 post-infection compared to mice infected with H99W (Figure 6(b)), suggesting the increased virulence in this route of infection was due to an increased Th2 response in mice.