Has strong anti-HIV activity against T-tropic strains of HIV-1 and weaker activity against M-tropic strains of HIV-1. Inhibits HIV-1 fusion and infection of CD4 LTR beta-gal cells in vitro. Inhibits fusion of HIV infected CEM-SS cells with uninfected CEM-SS cells, and fusion of HIV-1 Env expressing HL2/3 cells with CD4 LTR beta-gal cells. Binds to HIV gp120, HIV gp160 and to a lesser extent HIV gp41. Binding to HIV gp120 is glycosylation dependent. Binds with high specificity to the tetrasaccharide Man-alpha-1,2-Man-alpha-1,6-Man-alpha-1,6-Man and also binds the higher-order oligosaccharides oligomannose 8 and oligomannose 9. Does not bind to monosaccharides, complex or hybrid N-linked oligosaccharides or chitin.