Figure 4
HIV-inhibitory activity of Cistus incanus extract selectively targets viral envelope proteins.
(A) Antiviral components of Ci extract interact with virus particles but not target cells. The graph shows the effects of preincubation of virus inoculum (HIV-1LAI ) or target cells (LC5-RIC) with Ci extract on its anti-HIV-1 activity. As control, antiviral activity was assayed under standard conditions, in which virus inoculum and Ci extract were added to cells simultaneously. Symbols signify mean values for each extract dilution analysed in triplicate and error bars the standard deviation of the mean. Values for infection of cultures treated with Ci extract are expressed relative to untreated cultures (=100% infection). (B) Ci treatment blocks binding of virus particles to heparin. Virus capture assays were performed with heparin beads and virus samples containing HIV-1LAI, incubated either with (virus + Ci) or without Ci extract (virus only). Captured virus was quantified in the bead fraction (left panel) and in the eluate (right panel) by Gag-p24 ELISA. Levels of Gag-p24 antigen captured from Ci treated virus samples are expressed relative to Gag-p24 antigen levels captured from untreated control samples (=100%). Results are shown for two independent capture experiments performed with different amounts of virus. Gag-p24 levels were normalized to values measured for the control sample (virus only =100%). Columns signify mean values and error bars the standard deviation of the mean (nd = not detected). (C) Ci treated virus particles are captured by antibodies that bind to cell-derived CD44 proteins in virus envelopes. Virus captures assays were performed with microbeads conjugated with anti-human CD44 antibodies and HIV-1LAI virus samples incubated with (virus + Ci) or without Ci extract (virus only). Levels of captured virus were determined by Gag-p24 ELISA of the eluate (left graph). Infectivity of the captured virus was determined with LC5-RIC cells (right graph). Bars represent the mean results of 3 replicates for each sample and error bars the standard deviation of the mean.
