Figure 2.

Sal4 mAbs agglutinate live STm cells by flow cytometry. Mid log phase cultures of AR05 were washed in PBS and incubated with 2, 20, or 200 μg/mL Sal4 SIgA or IgG or isotype control antibodies for 1 h at 37 °C. 10 000 events per sample were analyzed on a BD FACSCalibur (BD Biosciences, San Jose, CA) by forward scatter (FSC) and side scatter (SSC) to visualize aggregate size and granularity. Gating was set on untreated AR05 cells, and agglutination was defined by SSC-positive FSC-positive cells (Q2 + Q4), similar to that previously described.³⁸ (A) Diagram demonstrating the antibody-to-bacterium ratio for each of the concentrations examined. (B, C) Representative flow cytometry plots showing FSC and SSC for (B) Sal4 SIgA and (C) Sal4 IgG and isotype control groups. STm cells treated with isotype control antibodies resulted in Q2 + Q4 values <1%. Results represent data from three separate biological experiments.