2G9-Salmonella specifically invades and rejects CD20-positive tumors in vivo, increasing mouse survival duration. (A) Quantification of in vivo intracellular 2G9-Salmonella vs GSTb1-Salmonella within CD20⁺ and CD20⁻ MCA203 tumors, 24 hours after intravenous delivery (n = 4 per group). (B) In vivo, intracellular organ biodistribution (liver, spleen, and tumor) of unmodified AT-Salmonella vs 2G9-Salmonella 24 hours after intratumoral delivery as assessed by gentamicin protection assay. n.d.= not detectable. (C-D) Tracking of acute-phase tumor growth after a single intratumoral injection of the indicated bacteria into mice bearing both CD20⁺ and CD20⁻ MCA203 tumors in opposite flanks (n = 5 mice per group [PBS and empty vector-AT-Salmonella] or 8 mice per group [2G9-AT]). (E) Kaplan-Meier curves of mice bearing either CD20⁺ or CD20⁻ MCA203 tumors injected twice with 2G9-Salmonella or empty vector-Salmonella (n = 6 mice per group). (F) Actual cfus injected as determined after injection by limiting dilution assay of the injected bacterial solution, bars 1 and 2 corresponding to the data presented in (A) and bars 3 and 4 corresponding to the data shown in (C) and (D). All data shown are from representative experiments, which were repeated 3 times, yielding similar results.