2G9-Salmonella efficiently interacts with and invades CD20-expressing cells. (A) Representative immunofluorescence images of CD20-expressing CT26 cells infected with control AT-Salmonella (left panel), 2G9-Salmonella (middle panel), or GSTb1-Salmonella (right panel) at MOI 10, showing extracellular bacteria (Cy5-positive [blue]), intracellular bacteria (Cy3-Cy5-double positive [red]), and cytoplasm/phalloidin (FITC [green]) staining. Images shown are representative of 3 separate immunofluorescence infection experiments comprising at least 5 randomly selected fields of view per infection. (B) Quantification of total number of bound per infection (extracellular + intracellular), determined from at least 4 immunofluorescence images per infection, normalized per the cell count in field of view. (C) Quantification of invasiveness of bound bacteria (intracellular/[intracellular + extracellular]). (D) Total number of bacterial cfus used in (A) and (B), as determined by limiting dilution assay of the bacteria used for infection. All images shown were taken with a 40× objective.