FIG. 1.

Biphasic effects of cellulose sulfate on HIV infection. (A) Data from the current study conducted at the National Institutes of Health. PBMC were prepared from a healthy HIV-negative donor by Ficoll-Plaque Plus density gradient centrifugation and cultured in RPMI-1640 with 10% fetal calf serum, 2 mM glutamine, 20 units/ml IL-2, and antibiotics. The cells were incubated with various concentrations of cellulose sulfate (Acros Organics) for 1 h at 37°C and then infected with the GFP-tagged R5-tropic reporter virus HIV-1_JR-CSF3-GFP.^7,8,25 After 72 h at 37°C, the extent of reporter virus replication was assessed by flow cytometry (Becton Dickinson FACS Calibur) by measuring the fraction of GFP⁺ cells, which appeared as off-the-diagonal dots in a plot of PE (background fluorescence) versus FITC (GFP signal).^7,25,26 The data represent the mean ± SD for quintuplicate wells from a single experiment and were normalized to 100% for the infection level in the absence of cellulose sulfate. (B) Data from CONRAD presented at the 2007 Annual meeting of the Alliance for Microbicide Development (http://www.microbicide.org/microbicideinfo/reference/Gabelnick.AMD10.pdf). This experiment also examined infection of PBMC by an R5 virus and normalized the data to a value of 100% in the absence of compound.