Figure 1.

Schematic representation of the expression cassettes inserted in TK locus of the five WR vaccinia virus candidates constructed for this study. The insertion of cassettes disrupted the TK gene. The RR gene (not shown here) was also deleted in all the virus used in this study. For mAb and Fab each chain (heavy and light) is under the control of a different and independent promoter (namely p7.5K or pH5R) with their own strengths (i.e., level of protein expression). Mab corresponds to the whole molecule with two heavy and two light chains assembled to form a bivalent molecule 2 × (Light + Heavy). Fab corresponds to one light chain assembled with one heavy chain lacking their dimerization domains (i.e., hinge and Fc). Fab is a monovalent molecule. ScFv corresponds to the genetic fusion of VH to VL via a poly-GS linker. ScFv is monovalent molecule but a fraction of it can dimerize to form a divalent molecule. The variable and the constant domains of the light and heavy chains are represented with hatched and plain patterns, respectively.