Consistent with our results with WT vs. Δhla, there were more IL-17+ CD4+ T cells in mice that received Hla-specific antiserum prior to infection, compared with those that received naïve serum (Supplementary Fig. 6A), but there were no significant differences in other IL-17+ or IFNγ+ T cell populations (Supplementary Fig. 6B, C). This evidence concerns the gene CD4 and infection.