GZMB and infection: In agreement, significantly reduced numbers of 4° effector OT‐I cells accumulated in the brains of mice during a fourth PbA‐OVA infection than 2° effector OT‐I cells in brains of mice during a secondary infection, with intracerebral 4° effector OT‐I cells also showing significantly reduced levels of GrB than intracerebral 2° effector OT‐I cells (Figure 6h,i).