However, CD4+ T cell deficiency does not affect the effector CD8+ T cell responding against E. cuniculi infection (Moretto et al., 2000), suggesting CD4+ T cell is not the sole activator of CD8+ T cell response and another reason is associated with the route of infection (Moretto et al., 2004; de Moura et al., 2019). The gene discussed is CD8A; the disease is infection.