TKT and glioblastoma: The results show that relative to phosphate-buffered saline (PBS), VLPs, or GCV only treatment and control VLP/GCV combination, tk-VLPs plus GCV reduced the viability of the cells significantly (Fig. 2), indicating that JCPyV VLPs delivered thymidine kinase suicide gene into human glioblastoma cells and induced cytotoxicity in combination with GCV.