Th the 10-1074 MAb, the median number of challenges for successful infection in the three-animal subgroup not experiencing the rapid anti-antibody induced decay, was 17.0 weeks compared to 12.5 for the entire 10-1074 recipient cohort. Probit analysis was also used to estimate the probability of infection as a function of the imputed plasma MAb concentration at the time of each challenge. The proba