Potent neutralizing antibody responses of rhesus macaques receiving concurrent intradermal administrations of four independent vaccines. A. Neutralizing antibody titers for animals in: A. botulinum neurotoxin type A challenge group. B. anthrax challenge group. C. SEB challenge group. Individual animals vaccinated with antigens plus AH, Vaccinated 1–6; injected with AH only, Control 1–2. All disease challenges occurred one month after the final vaccination. Geometric mean titers, based on triplicate determinations.