By day 5 after infection, bacterial load in Klkb1−/− mice was over 10-times higher than in WT animals (22.6 ± 9.0 × 107 versus 1.8 ± 0.8 × 107 photons/sec, P < 0.05 versus Klkb1−/−, Fig. 3, A and B). Here, KLKB1 is linked to infection.