Reduction in CD4 binding affinity associated with removal of a single glycosylation site in the external glycoprotein of HIV-2.

The role of selected glycosylation sites in the ability of the envelope glycoprotein of HIV-2 (gp 105) to bind to CD4 has been investigated. Loss of glycosylation sites at amino acids 410 and 447 did not affect the CD4 binding ability of gp 105 even when removed in pair combination. Loss of a single glycosylation site at amino acid 400, however, was sufficient to cause a reduction of at least 50-fold in the efficiency of receptor binding. These data support the hypothesis that some of the carbohydrate side chains on gp 105 have a profound effect on biological activity.