3-3--dioctadecyloxacarbocyanine and 2-2--dipyridyl-disulfide

The fusion of HIV and SIV with biological membranes was studied by photosensitized activation of a hydrophobic probe, [(125)I]iodonaphthylazide ([(125)I]INA), by a fluorescent lipid which is situated in the target membrane. Photosensitized labeling of viral envelope-resident proteins occurs only upon their insertion into target membranes. Photosensitized labeling as a result of HIV-1 Env-mediated cell fusion showed the same kinetics as aqueous dye transfer. We have for the first time measured kinetics of HIV and SIV virus-cell fusion. HIV-1(MN) virions were about 10x less fusion active than SIVmne virions. SIV inactivated by aldrithiol-2 retained fusion activity similar to that seen with untreated virus. The relatively slow time course of SIV-cell fusion (t(1/2) = 19 min) indicates that the fusion events are stochastic. This feature provides a basis for understanding the mode of action of HIV/SIV entry inhibitors that target transition states.

Topics: 2,2'-Dipyridyl; Animals; Azides; Carbocyanines; Cell Line; Disulfides; Fluorescent Dyes; Glycoproteins; HIV-1; HLA-DR Antigens; Humans; Iodine Radioisotopes; Kinetics; Membrane Fusion; Mice; Photochemistry; Photosensitizing Agents; Simian Immunodeficiency Virus; Sulfhydryl Reagents; Viral Envelope Proteins