EVALUATION OF THE COMBINATION EFFECT OF DIFFERENT ANTIVIRAL COMPOUNDSAGAINST HIV IN-VITRO

3'-azido-3'deoxythymidine (AZT), a clinically used anti-HIV compound, was evaluated for antiviral effect on HIV infection in combination wit h other antiviral compounds in vitro. Interactions were evaluated by t he median-effect principle and the isobologram technique. Synergistic effect was obtained by combining many evaluated antiviral agents with AZT. We observed a difference in the degree of synergism depending on the evaluated compound; the results indicate that compounds with the s ame target in the viral replicative cycle (ddI: 2',3'-dideoxyinosine, didanosine; d4T: 2',3'-dideoxy-2',3'-didehydrothymidine stavodine; TIB O: tetrahydro-imidazole-benzodiazepin) had a synergistic effect at all concentrations, agents that disturb the infectivity of virus (CAS: Ca stanospermine; AME: Amphotericin B Methyl Ester) exerted a strong syne rgistic effect at low concentrations, and finally compounds interferin g with the adhesion/penetration process of virus (ConA: Concanavalin A ; DS: dextran sulfate) were most potent with AZT when used in rather h igh concentrations. At this moment in the HIV epidemic, these observat ions suggest that combinations of antiviral compounds should be evalua ted in clinical trials, with the major emphasis on nucleoside analogue s and compounds influencing the infectivity of the virus.