TKT and urinary bladder cancer: The growth of A549 lung cancer cells injected with tk-JCPyV VLP-SPBs combined with GCV group (Fig. 5A, left side of fourth and fifth panels) did not differ from that of tumors in the tk-JCPyV VLP-SPB/PBS control (Fig. 5A, left side of the third panel), demonstrating the high specificity of tk-JCPyV VLP-SPBs for bladder cancer.