Figure 1. The benefit of antigenic variation in CD4+ T_H17 epitope is limited.

BALB/c mice were immunized by either CT alone (CT) or CT and ovalbumin (CT+OVA). All mice were challenged with a 1∶1 mixture of the antigen-negative (AVO) strain and the antigen-positive (OVA) strain. The density of intranasal colonization by pneumococcus in each mouse was determined on days 1, 4, and 8 after challenge as described in the Methods. Total CFU counts are shown in (A). The ratio between the two strains in each mouse was determined (B). The p values were derived from Mann-Whitney tests comparing the immunized with the control group on days 1, 4, and 8. Solid lines indicate group medians. The correlation between total CFU and the AVO/OVA ratio is shown for the immunized mice (C) and the control mice (D) that remained colonized on days 4 (triangle) and 8 (diamond).