Adenovirus (Ad) is a potent gene-delivery vehicle and has frequently been used for designing oncolytic viruses. However, lack of selectivity on infection has hampered the achievement of sufficient in vivo efficiency. Here, we developed a novel oncolytic virus system, infectivity-selective oncolytic adenovirus (ISOAd), via direct high-throughput screening of a high-diversity targeting-ligand library in adenoviral format. Through our newly designed rescue virus system, the high-diversity Ad library carrying the random seven amino acid sequences ligand-library in the AB-loop of its fiber-knob region (5 × 10 9 diversity) was successfully generated. During the screening of this library with the cells expressing the target molecule (mesothelin, MSLN), the AB-loop sequence of the virus clones converged to one dominant sequence and a novel MSLN-targeting sequence was isolated. The virus with the isolated motif showed selective infectivity to MSLN-positive cells in vitro. In vivo, it exhibited a selective and potent antitumor effect resulted from the viral replication in MSLN-positive xenografts. The ISOAd is a novel class of oncolytic Ad, which has selectivity at the step of transduction. The selectivity at the stage of infection can open new perspectives in oncolytic Ad therapy for various diseases.
Bibliographical noteFunding Information:
We thank Glen Nemerow (Scripps Research Institute, La Jolla, CA) for providing us with the 644 cells and pDV69, and Philip Ng (Baylor College of Medicine, Houston, TX) for the 116 cells. This work was supported by the National Institute of Health (R01CA94084 and R01CA168448 to M.Y. and P50CA101955 to S.M.V., J.D., and M.Y.). This work was done in Minneapolis, Minnesota, USA. The authors declared no conflict of interest.