A Recombinant Vaccinia Virus Expressing a Sodium/Iodide Symporter for Theranostics of Malignant Tumors Using Synchrotron Radiation

A recombinant strain of the vaccinia virus, VV-mNIS-dGF, has been constructed. The genome of this strain contains an insertion of the mouse sodium/iodide symporter transgene (mNIS). This insertion is located in the deleted region of the viral thymidine kinase gene (tk). In addition, the viral growth factor gene (vgf) was deleted, ensuring that the virus had an attenuated effect on normal cells without affecting its replication in cancer ones. The antitumor activity of the VV-mNIS-dGF strain in two mouse cancer models, melanoma B16-F10 and colorectal carcinoma CT-26, was studied. In both models, the strain exhibited high oncolytic activity, efficiently expressed the mNIS and accumulated iodide in tumor cells in both in vitro experiments and in vivo on mouse allografts. Quantification of the iodide content in tumors was performed by elemental analysis using X-ray Fluorescence Analysis with Synchrotron Radiation (XRF-SR). The results indicate the possibility of using the VV-mNIS-dGF strain for both therapy and diagnosis (theranostics) of malignant tumors.