FIG. 4.

INA inhibits fusion of SIV envelope with the target cell membrane. SIV Mne was treated with INA at the concentrations indicated. Photosensitized labeling was used to determine fusion activity at the plasma membrane level by measuring the extent of ¹²⁵INA incorporation into viral HLA-DR (α-chain) upon fusion with the target cell membrane. The maximal INA concentration applied for inactivation was 2 μM, because higher concentrations interfered with the incorporation of ¹²⁵INA in the assay. The experiment was repeated two times with similar results.