Studies of passive immunization in newborn macaques. A. Passive administration of high concentrations of various combinations of the first-generation HuMoNAbs (b12, 2G12, 2F5, 4E10, F105) (white arrow) before or simultaneously with intravenous or oral challenge with SHIVs (green arrow) protected neonatal rhesus macaques against infection: there was no infection [4, 149, 150]. B. There was no protection when the first-generation HuMoNAbs (white arrow) were administered more than 12 hours post-virus inoculation (green arrow) . C. New second-generation HuMoNAbs (PG-, PGT-, VRC-series) that are 10- to 100-fold more potent in vitro than the first-generation HuMoNAbs have been identified [96, 115–117, 152, 153]. It would be interesting to re-evaluate the potential protective potency of NAbs in newborn macaques when administered either before or after (white arrow) viral exposure (green arrow).