Studies on the pathogenesis of monkey pox

Summary

Monkey pox virus (MPV), titrated intramuscularly in cynomolgus monkeys provided a 50 per cent infectivity endpoint of 10^−5.8. All infected animals developed monkey pox. Three of 4 sentinel control monkeys developed monkey pox; one experienced subclinical infection. Viremia intervenes between the 4th and 7th days, and may persist for 4 or 5 days post-eruption, even after appearance of HI antibodies. MPV multiplies in the substance of the inoculated muscle. During the pre-eruptive stage of infection this virus is detected earliest in tonsil and spleen, and shortly thereafter in bone marrow and regional lymph nodes. During the early post-eruptive period, in addition to large concentrations of MPV in these same tissues, the virus is regularly found in cutaneous lesions, some-what less regularly in kidney, and very much less regularly in other tissues. Specific antibodies are raised during infection; HI antibodies are less enduring than CF or neutralizing antibodies. Monkeys convalescent from MPV are immune to challenge with vaccinia, but are fully susceptible to Yaba tumor virus.