Oncolytic adenoviruses (Ads) have been shown to be safe and have great potential for the treatment of solid tumors. However, the therapeutic efficacy of Ads is antagonized by limited spread within solid tumors. To develop Ads with enhanced spread, viral particles of an E1-wildtype Ad5 dl309 was repeatedly treated with UV type C irradiation and selected for the efficient replication and release from cancer cells. After 72 cycles of treatment and cancer selection, AdUV was isolated. This vector has displayed many favorable characteristics for oncolytic therapy. AdUV was shown to lyse cancer cells more effectively than both E1-deleted and E1-wildtype Ads. This enhanced cancer cell lysis appeared to be related to increased AdUV replication in and release from infected cancer cells. AdUV-treated A549 cells displayed greater expression of the autophagy marker LC3-II during oncolysis and formed larger viral plaques upon cancer cell monolayers, indicating increased virus spread among cancer cells. This study indicates the potential of this approach of irradiation of entire viral particles for the development of oncolytic viruses with designated therapeutic properties.

Adenoviruses (Ads) have been extensively manipulated for the development of cancer selective replication, leading to cancer cell death or oncolysis. Clinical studies using E1-modified oncolytic Ads have shown that this therapeutic platform was safe, but with limited efficacy, indicating the necessity of targeting other viral genes for manipulation. To improve the therapeutic efficacy of oncolytic Ads, we treated the entire Ad genome repeatedly with UV-light and have isolated AdUV which efficiently lyses cancer cells as reported previously (Wechman, S. L. et al. Development of an Oncolytic Adenovirus with Enhanced Spread Ability through Repeated UV Irradiation and Cancer Selection. Viruses 2016, 8, 6). In this report, we show that no mutations were observed in the early genes (E1 or E4) of AdUV while several mutations were observed within the Ad late genes which have structural or viral DNA packaging functions. This study also reported the increased release of AdUV from cancer cells. In this study, we found that AdUV inhibits tumor growth following intratumoral injection. These results indicate the potentially significant role of the viral late genes, in particular the DNA packaging genes, to enhance Ad oncolysis.

Adenoviruses (Ads) have been extensively manipulated for the development of cancer selective replication, leading to cancer cell death or oncolysis. Clinical studies using E1-modified oncolytic Ads have shown that this therapeutic platform was safe, but with limited efficacy, indicating the necessity of targeting other viral genes for manipulation. To improve the therapeutic efficacy of oncolytic Ads, we treated the entire Ad genome repeatedly with UV-light and have isolated AdUV which efficiently lyses cancer cells as reported previously [1]. In this report, we show that no mutations were observed in the early genes (E1 or E4) of AdUV while several mutations were observed within the Ad late genes which have structural or viral DNA packaging functions. This study also reported the increased release of AdUV from cancer cells. In this study, we found that AdUV inhibits tumor growth following intratumoral injection. These results indicate the potentially significant role of the viral late genes, in particular the DNA packaging genes, to enhance Ad oncolysis.