question: Abstract Exposure of carbohydrate-binding agents (CBAs) (i.e. the mannose-specific plant lectins Hippeastrum hybrid agglutinin and Galanthus nivalis agglutinin) to HIV-1 progressively select for mutant HIV-1 strains that contain N-glycan deletions in their envelope gp120. This results in resistance of the mutant virus strains to the CBAs. Exposure of such mutant virus strains to the α(1,2)-mannosidase I inhibitor 1-deoxymannojirimycin (DMJ) results in an enhanced suppression of mutant virus-induced cytopathicity in CEM cell cultures. Moreover, when combined with CBAs at concentrations that showed poor if any suppression of mutant virus replication as single drugs, a synergistic antiviral activity of DMJ was observed. These observations argue for a combined exposure of CBAs and glycosylation inhibitors such as DMJ to HIV to afford a more pronounced suppression of virus replication, prior to, or during, CBA resistance development.