Was administered intravenously to individual animals in four cohorts of monkeys. Virus challenge The origin and preparation of the tissue-culture-derived SHIVAD8-EO stock have been previously described25. One week following MAb infusion, animals were challenged intrarectally with 10 TCID50 of SHIVAD8-EO, and every week thereafter, until a virus infection was established. A pediatric nasal speculum