Figure 4

The fibril-mediated enhancement of HIV-1 infectivity is dependent on the membrane fusion activity of gp41. (A) TZM-bl cells were infected with R4 tropic HIV-1 strain NL4-3 (wt) or protease cleavage site mutant derivate (Prot.Xa), which were pre-incubated for 5 min at RT with Aβ(1–42) fibrils (50 μg/ml). Infection-induced luciferase activity was assayed 48 h post infection. (B) Immunoblot analysis of HEK 293T cells transfected with pNL4-3 or the protease cleavage site mutant pNL Prot.Xa by using Chessie 8 antibody (NIH) for gp160/gp41 analysis [15] and the p24 specific antibody (D7320, Aalto Bioreagents Ltd. Dublin, Ireland) for capsid protein detection. Virions were pelleted by using sucrose centrifugation as described before [16].