FIG. 4.

Anionic polymers inhibit SEVI-mediated enhancement of viral fusion. (A) BlaM-Vpr-containing NL4-3 virions were incubated with SEVI and different concentrations of the indicated polyanionic compounds. The virions were then diluted fivefold to a final concentration of 50 ng/ml and added to CD14⁻ CD4⁺ T cells. The level of viral fusion in the absence of SEVI is indicated by the bottom dotted line, whereas the level of viral fusion in the presence of SEVI is indicated by the top dotted line. At concentrations greater than 8 μg/ml, heparin, oversulfated heparin, dextran sulfate, and oversulfated chondroitin sulfate inhibited SEVI activity. Desulfated heparin and chondroitin sulfate had minimal inhibitory effect at all of the concentrations tested. Results are representative of data from five separate experiments. (B) CD14⁻ CD4⁺ T cells were incubated with SEVI and different concentrations of the indicated anionic polymers. The cells were then washed and infected with BlaM-Vpr-containing NL4-3 and analyzed by flow cytometry for virion fusion. The level of viral fusion in the absence of SEVI is indicated by the bottom line, whereas the level of viral fusion in the presence of SEVI is indicated by the top dotted line. At concentrations greater than 8 μg/ml, heparin, oversulfated heparin, dextran sulfate, and oversulfated chondroitin sulfate inhibited SEVI activity. Desulfated heparin and chondroitin sulfate had minimal inhibitory effect at all of the concentrations tested. Results are representative of data from five separate experiments.