In-vivo-targeted gene delivery using adenovirus-antibody site-specific covalent conjugates

Safe and efficient nucleic acid delivery to targeted cell populations remains a challenge in the fields of cell and gene therapy. Toward this end, we attempted to utilize the "DogTag-DogCatcher" system to target adenoviral vectors. "DogTag" is a short peptide that forms a spontaneous isopeptide bond upon mixing with its partner protein, "DogCatcher." We genetically incorporated the DogTag peptide into the protein responsible for initial binding of the virus to its target cell, the fiber. This allowed permanent linking of DogCatcher-fused single-domain or single-chain antibodies at the fiber. This modification allowed simple, effective, and exclusive targeting of the vector to cells bound by the linked antibody. This enhanced gene transfer into primary B and T cells by up to 60-fold in vitro and 2- to 3-fold in vivo in mice without other alterations to vector tropism. Although the system's in vivo performance is currently suboptimal and additional engineering is needed prior to further use, these studies form the basis of a novel method for targeting adenovirus that can be combined with additional well-characterized adenovirus modifications toward applications in cell engineering, gene therapy, vaccines, oncolytics, and others.