To 18 challenges (median = 14.5) for all of theAuthor Manuscript Author Manuscript Author Manuscript Author ManuscriptNature. Author manuscript; available in PMC 2016 November 29.Gautam et al.Pagemonkeys to become infected (Fig. 1f). Thus the modified VRC01-LS Fc domain conferred an estimated 1.8-fold increase in the number of challenges resulting in successful acquisition compared to the parental