Sugar-binding proteins potently inhibit dendritic cell human immunodeficiency virus type 1 (HIV-1) infection and dendritic-cell-directed HIV-1 transfer.

Both endocytic uptake and viral fusion can lead to human immunodeficiency virus type 1 (HIV-1) transfer to CD4+ lymphocytes, either through directional regurgitation (infectious transfer in trans [I-IT]) or through de novo viral production in dendritic cells (DCs) resulting in a second-phase transfer to CD4+ lymphocytes (infectious second-phase transfer [I-SPT]). We have evaluated in immature monocyte-derived DCs both pathways of transfer with regard to their susceptibilities to being blocked by potential microbicidal compounds, including cyanovirin (CNV); the plant lectins Hippeastrum hybrid agglutinin, Galanthus nivalis agglutinin, Urtica dioica agglutinin, and Cymbidium hybrid agglutinin; and the glycan mannan. I-IT was a relatively inefficient means of viral transfer compared to I-SPT at both high and low levels of the viral inoculum. CNV was able to completely block I-IT at 15 microg/ml. All other compounds except mannan could inhibit I-IT by at least 90% when used at doses of 15 microg/ml. In contrast, efficient inhibition of I-SPT was remarkably harder to achieve, as 50% effective concentration levels for plant lectins and CNV to suppress this mode of HIV-1 transfer increased significantly. Thus, our findings indicate that I-SPT may be more elusive to targeting by antiviral drugs and stress the need for drugs affecting the pronounced inhibition of the infection of DCs by HIV-1.