Mechanism of inhibitory effect of dextran sulfate and heparin on replication of human immunodeficiency virus in vitro

The sulfated Polysaccharides dextran sulfate and heparin have proved to be potent and selective inhibitors of human immunodeficiency virus type 1 (HIV-1) in vitro. Dextran sulfate (Mr 5000) and heparin (Mr 15,000) completely protected MT-4 cells against HIV-1-induced cytopathogenicity at a concentration of 25 micrograms/ml. Their 50% inhibitory concentrations were 9.1 micrograms/ml (dextran sulfate) and 7.0 micrograms/ml (heparin), respectively. No toxicity for the host cells was observed with these compounds at a concentration of 625 micrograms/ml. The anti-HIV-1 activity of heparins of various molecular weights correlated well with their anticoagulant activity. On the other hand, with dextran sulfates of low molecular weight (5000, 8000) a significant inhibitory effect on HIV-1 was achieved at a concentration that was not markedly inhibitory to the blood coagulation process. Dextran sulfate and heparin were not inhibitory to HIV-1 Reverse Transcriptase unless they were used at concentrations in excess of those that inhibited HIV-1 replication. They were highly effective against HIV-1 replication even when present only during the 2-hr virus adsorption period. Studies using radiolabeled HIV-1 virions indicated that dextran sulfate and heparin inhibit virus adsorption to the host cells.