After demonstrating that JCPyV VLP could carry the GFP gene to express in the 22Rv1 orthotopic prostate tumors in mice and that FMT can determine the fluorescence intensity of 22Rv1-iRFP-GFP cells, we further examined the inhibitory capability of JCPyV VLP (carrying the tk suicide gene) on the growth of orthotopic prostate tumors in the presence of GCV. The gene discussed is TKT; the disease is prostate neoplasm.