Experimental design. Sixteen rhesus macaques were inoculated with SIVmac251 and monitored for viral loads and SIV-specific immunity. Five succumbed within a year after SIV inoculation (48, 222, 223, 231, and 240 days after SIV infection) and the remaining 11 monkeys were vaccinated with ML29 or LCMV-Armstrong on day 393 after SIV-infection. A month after the vaccination, five monkeys (ML-1, SIV/ML-1, SIV/ML-2, SIV/ML-6, SIV/ML-7) were boosted with ML29. Necropsies for 6 animals were performed on days 426, 452, 458, 491, 505, and 516 (after SIV). Five months after ML29 vaccination, 5 animals were still surviving. (X) indicates the relative position on the timeline of samplings and necropsies.