Poxvirus infection of the baboon (Papio cynocephalus).

Ten serial passages of monkeypox (MPV), vaccinia, variola, and chimpanzeepox (chimp-9) viruses were performed in baboons (Papio cynocephalus) via skin scarification. Comparisons of clinical and virological results indicate that MPV and vaccinia are very closely related and that variola and chimp-9 viruses are identical. These findings suggest that infections of simians with chimp-9 virus resulted from contact with variola virus, the source of which is still unknown. On the other hand, MPV in monkeys may have resulted from contact with recently vaccinated humans, serial passage through simian hosts resulting in the biological alterations that produced MPV.