Inactivation of HIV-1 by 2DLT. Recombinant proteins and peptides were added to HIV-1 Bal (A), HIV-1 IIIB (B), and 92US657 (C), respectively, followed by incubation for 60 minutes at 4°C. The mixtures were then cooled on ice before addition of PEG-6000 solution at a final concentration of 3% for separation of HIV-1 particles as described in the Methods. The HIV-1 particles containing pellets were re-suspended in tissue culture medium and titered for infectivity. The percentage of residual infectivity is shown in a scale. The data are representative of results from three similar experiments performed in triplicate (means ± SD).