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. The gene discussed is TNF; the disease is infection.