Figure 5.
Fibril structure and charge are critical for cationic peptide enhancement of HIV-1 infection. CEMx M7 cells were infected with HIV-1 in the presence of increasing concentrations of self-assembled peptides with 1), net positive charges (shown in red): SEVI, K4(FKFE)2, K2(FKFE)2, K4(ChaKChaE)2, K2(ChaKChaE)2; 2), net negative charges (shown in blue): E4(FKFE)2, E2(ChaKChaE)2; and 3), unassembled positively charged peptide (shown in orange): K2(AKAE)2. At 48 h post-infection, cells were harvested and luciferase measured as a readout of HIV-1 infection. Results represent mean values from three experimental replicates; error bars denote the standard deviation of these values. The results shown are representative of three independent experiments performed with a range of peptide concentrations all yielding similar results. Notes: 1), All peptide concentrations refer to final concentrations in cell culture (and not to concentrations during virion preincubation, which were higher); and 2), we have plotted the data on a semilog scale, to facilitate comparison of values obtained at low concentrations. Because the log of zero is not defined, we were obliged to use a discontinuous x axis to do this. The far left portion of the x axis is thus plotted with a linear (ordinary) axis to accommodate the value x = zero.