To confirm the efficacy of humanized E16, wild-type mice were administered three different versions of purified Hm-E16 at day 2 after infection. Although Hm-E16 variants protected mice against lethal infection (Fig. 4f) , at a dose of 4 µg, the variant (16.3) that showed the highest affinity for DIII (Fig. 4c) was more protective (67% versus 46% survival; mean survival time of 14 ± 1 d versus 11 ± 2 d, P = 0.04).