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We now report the confirmation of the work of Hollingshead et al. (1995) on development of a cell based hollow fiber (HF) system for evaluating potential anti-AIDS drugs in vivo using conventional mice rather than SCID mice. CD4 +, CEM-SS cells infected with HIV/1, strain RF, at a multiplicity of infection of 0.1 were placed into HFs. The fibers were implanted into the peritoneal cavity of outbred Swiss mice. Using this model, the antiviral activity of azidothymidine (AZT) at doses of approximately 150, 75 and 37.5 mg/kg/day was evaluated by administering AZT to the mice in drinking water. Upon fiber removal on day 6, AZT treatment was shown to significantly increase CEM cell viability over the untreated, virus control group and significantly reduced the levels of HIV p24 and HIV RT activity.

Ribavirin has been reported to enhance the activity of ddI against HIV. We explored this enhancement of antiviral activity in Rauscher murine leukemia virus (RMuLV) models in vitro and in vivo. The significant finding in these studies was that combinations of the drugs exhibited virus titer reductions that were greater than would be expected if the drug interactions were simply additive. These effects were designated synergistic by the method of Prichard and Shipman (Prichard, M.N. and Shipman, C., Jr. (1990). A three-dimensional model to analyze drug-drug interaction, Antiviral Res. 14, 181-206). In addition to the antiviral synergy, we also observed some synergistic toxicity in the animal model.