The potential for heparin and its derivatives in the therapy and prevention of HIV-1 infection.

Heparin is one of several sulphated polysaccharides which potently inhibit replication of the human immunodeficiency virus type 1 (HIV-1) in cultures of CD4+ve human cells. The EC50 value is around 5 microg ml(-1). We have demonstrated that heparin binds to recombinant gp120, the envelope glycoprotein of HIV-1, at a site termed the V3 loop, or principle neutralizing domain, which consists of a disulphide-bridged loop of 32-35 amino acids particularly enriched with basic residues. Using a series of chemically modified heparins we have shown that there is structural specificity in the anti-HIV activity of heparin. Heparin is routinely used clinically as an anticoagulant, and has proved essentially non-toxic and well tolerated. Low anticoagulant derivatives of heparin which retain high anti-HIV-1 activities in vitro may be generated by several routes. Such preparations are ideal candidates for clinical investigation as potential novel therapeutic agents for use in combination with other drugs in the management of AIDS and HIV infection.