EFFECTS OF INITIATION OF 3'-AZIDO,3'-DEOXYTHYMIDINE (ZIDOVUDINE) TREATMENT AT DIFFERENT TIMES AFTER INFECTION OF RHESUS-MONKEYS WITH SIMIANIMMUNODEFICIENCY VIRUS

The effects of initiating treatment with 3'-azido-3'-deoxythymidine (z idovudine) at different times after inoculation of simian immunodefici ency virus (SIV) were investigated in rhesus monkeys. Zidovudine treat ments of 100 mg/kg/day (25 mg/kg, subcutaneously every 6 h) were initi ated 1, 8, 24, or 72 h after intravenous inoculation of 10 ID50 of SIV . Treatments continued for 28 days, and results were compared with tho se of saline-treated controls. Serum infectious virus titers 14 days a fter inoculation (AI) significantly decreased after treatment initiati on 1, 8, or 24 h Al. Titers were correlated with the time treatment wa s initiated. Treatments initiated 1-72 h Al prevented the establishmen t of persistent SIV antigenemia; greater effects were observed with ea rlier initiation of treatment. Treatments initiated 1-8 h Al resulted in decreased levels of viral antigenemia 14 days Al and delayed decrea ses in CD4+CD29+ blood lymphocytes. Earlier treatment initiation resul ted in delayed recurrence of antigenemia, with a tendency for longer s urvival. Early initiation of treatment may be important for limiting i nitial viral replication and dissemination in cases of known exposure.