A schematic representation of the chimeric Ad5 fiber. Notes: (A)
Incorporation of T4-phage fibritin–HGF/NK2 (251 amino acids) into the Ad fiber
knob. (B) Since the Ad5 fiber knob initiates and maintains the trimerization of the entire
fiber, it was replaced by the bacteriophage T4 fibritin protein containing a foldon domain
to maintain trimerization of the fiber protein. The HGF/NK2 is used as the targeting
ligand. Abbreviations: HGF, hepatocyte growth factor; aa, amino acids; Ad5,
adenovirus serotype 5; NK2, a secreted truncated splicing variant that extends through the
second kringle domain.