Genetic incorporation of a herpes simplex virus type 1 thymidine kinase and firefly luciferase fusion into the adenovirus protein IX for functional display on the virion.

An advantage of the adenoviral vector is its molecular flexibility, which allows for vector tropism modifications for the purpose of cell targeting. In addition to targeting ligands, the capacity to incorporate heterologous peptides has allowed capsid incorporation of other functionalities. We have defined the minor capsid protein IX (pIX) as a locus capable of presenting incorporated ligands on the virion surface. Thus, we sought to exploit the possibility of incorporating functional proteins at pIX. In our current study, we sought to expand the potential utility of our capsid labeling strategy by developing simultaneous imaging capacity for dedicated small animal positron emission tomography and bioluminescence imaging on a single adenoviral vector. Therefore, we constructed an adenovirus that incorporates a fusion protein of herpes simplex virus type 1 thymidine kinase and firefly luciferase (Luc) (TK-Luc) into adenovirus capsid pIX. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional TK-Luc as a component of their capsid surface. Most importantly, Ad-pIX-TK-Luc retained dual enzymatic functions in vitro and in vivo. This dual-modality approach will allow dynamic or real-time imaging analysis of adenovirus-based interventions with maximized analytic flexibility and enhanced resolution potential.