Fig. 8. Enhanced in vivo antibacterial efficacy of DAR18 TXC. One day after i.v. infection with S. aureus USA300, mice were treated with a single i.v. dose of αWTA/XTEN₁₄₄-dmDNA31₁₈ (DAR18 TXC, blue), αWTA/dmDNA31₂ (DAR2 TDC, black), or free mAb (purple). Four days after infection, bacterial burden in kidneys was determined by CFU determination. (A) When treated with an equimolar dose of either 23 nmoles mAb per kg (i.e., nmoles conjugate per kg) or 210 nmoles of mAb per kg, DAR18 TXC showed significantly higher kidney CFU reduction compared to DAR2 TDC. (B) When doses were compared by matching payload molarity side-by-side, efficacy of DAR18 TXC and DAR2 TDC was similar, indicating that the enhancement in efficacy in (A) was approximately proportional to the 9-fold increase in DAR. Bars, geometric means; lower dashed line, lower limit of detection; upper dashed line, i.v. infection inoculum. P values indicate difference between DAR18 TXC and DAR2 TDC, as determined by Mann–Whitney test; n.s., not significant.