Induction, Course, and Transmissibility of Monkeypox in the Baboon (Papio cynocephalus)

All of six baboons (Papio cynocephalus) inoculated intramuscularly with monkeypox virus became infected and one died. Two of six sentinel animals also became infected through natural transmission of the virus from infected roommates. Clinical symptoms observed included the formation of vesicular lesions on the extremities, face, lips, and buccal cavity approximately eight days after infection. At the same time HAI and plaque-neutralizing (PN) antibodies were detected. One week later CF antibody was formed. Peak titers of antibody were reached within one week after they were first detected. With the exception of PN antibodies, a gradual decline to a plateau was noted over a 16-week period. Immunity after natural infection was demonstrated by failure of animals to develop disease when they were given a challenge inoculation of monkeypox virus intramuscularly. The results suggest that it would be advisable to immunize colonies of primates in captivity against monkeypox.