Human adenovirus type 5 (Ad5) became the first oncolytic virus approved for commercial use in 2005 through intratumoral injection. However, problems still remain when the virus is injected systemically. In recent findings, when a dose of competent adenovirus was administered systemically, the virus was sequestered by the liver, causing complications rather than delivering therapeutics to the tumor. In order to cease accumulation in the liver, a modified adenovirus was designed by altering the hexon, which is a major component of the outer shell of the virus. This alteration inhibited the binding of blood factors that normally transport the virus to the liver. The goal of this study was to develop an adenovirus that would detarget the liver, but also retarget the virus to tumors. In order to retarget the virus, the knob domains of the trimeric fiber on the adenovirus were modified by insertion of small cell targeting peptides into the HI loop of the protein. To determine if the peptides disrupted fiber function, the proteins were expressed in mammalian cells and assayed for their ability to trimerize by western blot. Trimeric fiber constructs were then recombined into plasmid 823, which contains most of the viral genome. The final step involved recombining plasmid 823 with plasmid 855, which contains the E1 region of the viral genome, thus completing the viral genome and creating a virus. The virus would then be used to infect cancer cells as a precursor to infecting in vivo through systemic injection. Successful creation of the virus would show detargeting of the liver and retargeting of specific tumor cells.
Erin Witek, ’10 Chicago, IL
Majors: Biochemistry and Molecular Biology, Psychology
Dr. Michael Barry
Mayo Clinic Immunology
Sponsor: Craig Tepper