However, in the genetically susceptible Mdr1a−/− (epithelial transporter gene) mice model, which develops spontaneous colitis, infection with T. muris augmented the progression of colitis indicated by a significant increase in histological damage score, pro-inflammatory cytokines, and infiltration of mucosal CD4+ T-cell and DCs [142] (Figure 2). The gene discussed is CD4; the disease is infection.