Figure 1

HIV binding to cell-surface expressed α4β7. a Direct binding of SF162 (left panel) and CAP88 (right panel) viruses to α4β7 expressed on 293T cells measured by p24-FITC staining. For SF162, both the IEC and IMC (solid and dashed black lines respectively) bound α4β7 at similar levels which were higher than the untransfected α4β7⁻ 293T cells (grey line). The IEC of CAP88 T/F (solid black line) bound better than CAP88 12M (dashed black line). This is representative of 3 independent experiments. b Competition assay where CAP88 T/F (black dashed) bound to the integrin is measured as a decrease in α4-PE antibody binding relative to unbound α4β7 transfected 293T cells (black solid). HP2/1 and Act-1 binding in the absence of virus were used as positive controls (red and blue respectively) while the negative control was untransfected cells incubated with virus. Results are representative of four independent experiments. The CAP88 T/F virus bound significantly better to the α4β7 integrin compared to the 12 month IEC in the competition binding assay as shown in the bar graph (p = 0.018; paired t test). Bars represent the mean binding percentage of three independent experiments and the error bars represent the SEM.