Effective antiviral prophylaxis and therapy by systemic application of human interferon in immunosuppressed monkeys.

Rhesus monkeys treated with antilymphocytic globulin were infected with vaccinia virus or with Medical Lake macaque Herpesvirus. At the sites of inoculation of vaccinia virus, animals not treated with interferon developed typical pustulous reactions and then smaller secondary lesions. Human leukocyte interferon (5 X 10(5) international units per day) injected intramuscularly, either from one day before to three days after infection or for seven days beginning on the first day of primary reaction, suppressed the development of secondary lesions but did not influence the primary reaction. Infection with Herpesvirus caused a vesicular rash similar to that of human varicella. Through prophylactic treatment with human leukocyte interferon, the disease was completely averted in two of four monkeys, and in the other two the rash was delayed. Therapy initiated when the first lesions appeared prevented the enlargement and generalization of lesions in all of four monkeys. Formation of serum antibodies was only slightly influenced by human leukocyte interferon. The results suggest that systemic treatment with interferon, begun either prophylactically or therapeutically with the first symptoms, can be effective in immunosuppressed patients.