FIG. 9.
Timing of exposure of cold-induced epitopes on the HIV-1 envelope glycoproteins. Viruses with VSV G and ADAfl, KB9, or YU2 envelope glycoproteins or their H66N counterparts were kept at −80°C (initial) or incubated on ice for the indicated times. Viruses with only VSV G (VSV) or lacking envelope glycoproteins [ENV(−)VSV(−)] were studied in parallel as controls. Viruses were captured on antibody-coated wells and quantitated by adding Cf2Th target cells and measuring luciferase activity 48 h later.