Sulphoevernan, a polyanionic polysaccharide, and the narcissus lectin potently inhibit human immunodeficiency virus infection by binding to viral envelope protein

¹ Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität, Duesbergweg 6, 6500 Mainz
² Institut für Medizinische Mikrobiologie, Abteilung Experimentelle Virologie, Obere Zahlbacher Strasse 67, 6500 Mainz, F.R.G.
³ Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, U.K.
and⁴ Southern Research Institute, Virology Division, 2000 Ninth Avenue South, Birmingham, Alabama 35255-5305, U.S.A.

Sulphoevernan is a sulphated α-1 3, 1 4 polyglucan (M_r 20000) with a helical structure. This compound effectively inhibits both human immunodeficiency virus type 1 (HIV-1) and type 2 infection of cells in vitro at concentrations around 0.5 µg/ml. Moreover, the compound completely inhibits HIV-1-induced syncytium formation at a concentration of 1 µg/ml. Competition experiments with ³⁵S-labelled sulphoevernan revealed that the mannose-specific lectin from Narcissus pseudonarcissus prevented binding of sulphoevernan to HIV-1, whereas the antibody OKT4A did not reduce the amount of sulphoevernan bound to MT-2 cells. These data indicate that the non-cytotoxic polymer sulphoevernan binds to the virus rather than to the host cell. In vivo studies, using Rauscher leukaemia virus in NMRI mice, revealed that, at a daily dose of 20 mg/kg, the animals were protected against virus-induced increases in spleen weight. From these in vitro and in vivo data we conclude that sulphoevernan has potential in the treatment of acquired immunodeficiency syndrome.