While it appears that the CTLA-4, PD-1/PD-L1, and IL-10-R pathways independently regulate host resistance to P. berghei ANKA infection of BALB/c mice, further studies are also needed to understand the role that the CTLA-4 and/or PD-1/PD-L1 axes are playing in the context of IL-10R and to identify whether there is a primary regulatory pathway for T cells in this infection model. This evidence concerns the gene PDCD1 and infection.