In vitro neutralization and effector functions of SHIVIG against the challenge virus, SHIV-2873Nip. A. Neutralizing activity of SHIVIG in PBMC assays with or without NK cells. Serially diluted SHIVIG was assayed with unfractionated human PBMC (red) and PBMC depleted of NK cells (blue) in triplicates. VRC01 was used as a positive control and was analyzed with unfractionated human PBMC (solid grey line) and PBMC depleted of NK cells (dashed grey line) as described in Methods. B. ADCVI activity of SHIVIG and HIVIG (IgG from a pool of HIV-positive donors; positive control; squares) was assessed against SHIV-2873Nip as described in Methods. The graph shows the percentage of virus inhibition (y axis) by increasing concentrations of SHIVIG (red) or HIVIG (grey) normalized by values obtained for negative controls at the same concentrations. C. ADCC activity of serially diluted SHIVIG (red) and SHIVIG-derived Fab (grey) were tested in triplicates with CEM-NKr target cells coated with gp120 of HIV96ZM651 (clade C) and human PBMC as effector cells. The graph shows killing (in percentage) of target cells in the presence of increasing concentrations of SHIVIG or SHIVIG-Fab. Experiments were repeated in triplicate, and representative mean results are shown.