Fig. 1.

Design of the bifunctional adapter DE1scFv-pSia for tumor retargeting of antiadenoviral antibodies. a Illustration of the adenovirus capsid protein hexon generated by ExPASy software using the SWISS-Model tool^68,69 showing the exposed domains DE1, FG1 and FG2. The domain DE1 is highlighted by a dotted circle b The structure of the adapter molecule DE1scFv-pSia containing the DE1 domain (DE1) provided with a myc/his tag which was linked to an anti-PolySia scFv fragment via a glycine/serine stretch (Linker). c ELISA showing the recognition of purified, immobilized DE1scFv-pSia by IgG in serum of Ad5-naive, or in serum of Ad5-immunized mice pretreated with or without soluble DE1scFv-pSia as competitor (group: Ad5⁺ + DE1scFv-pSia) to inactivate DE1-specific IgG (n = 3). d Recognition of immobilized DE1scFv-pSia or Ad5-particles by IgG1 and IgG2a in serum of Ad5-naive (n = 3) and Ad5-immunized (Ad5⁺; n = 4) mice was measured by ELISA. e Binding of DE1scFv-pSia to the polySia-positive human cancer cell lines IMR32 and TE671 and the murine polySia-expressing cancer cells CMT-pSia, MC38-pSia, and B16F10-pSia was measured via flow cytometry. polySia-negative human Panc01 cells were used as negative control. Binding of DE1scFv-pSia to the cell surface was detected using an anti-myc-tag antibody. PolySia expression on the cell surface was measured using the specific antibody mAb735. Two-tailed unpaired t test was used to calculate statistics in c and d: *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001. Error bars refer to standard deviation (SD). Source data are provided as a source data file