INHIBITORY EFFECTS OF NOVEL MANNOSE-BINDING LECTINS ON HIV-INFECTIVITY AND SYNCYTIUM FORMATION

Several new lectins were isolated and characterized with respect to their composition and sugar binding specificities and their ability to prevent HIV-1 infection. Twelve of the 13 mannose-specific lectins were inhibitory to varying degrees. The most effective were Machaerium biovulatum agglutinin (MBA) and M. lunatus agglutinin (MLA) which at 0.4 mug ml-1 prevented the cytopathic effect of the virus. Lower protection was obtained with Bowringia mildbraedii agglutinin (BMA), Galanthusnivalis agglutinin (GNA), Lablab niger agglutinin (LNA) and Dolichos lablab agglutinin (DLA). All these lectins are more protective than Con A while MBA is nearly 10 times more potent than any previously reported lectin. In each case the selective antiviral activity appears to be due to interaction with virus and not with some component on the target cell. MBA and GNA immobilized on Sepharose specifically bound gp120. Studies of binding to glycoproteins confirmed the recognition of particular isomers of high mannose oligosaccharides Man9 to Man7GlcNAC2 by BMA and of Man5GlcNAc2 glycopeptides by GNA. By contrast, MBA did not bind oligomannosidic structures but did interact with ovalbumin, a glycoprotein rich in hybrid-type glycans.