Fig. 1.

Schematic representation shows measles virus–sodium-iodide symporter (MV-NIS) genome and its function. Virus-infected tumor cells release new viral progeny and are able to fuse readily with their uninfected neighboring cells to form multinucleated syncytia that eventually die. Infection with MV-NIS also leads to membrane expression of NIS, which is intrinsic transmembrane protein normally expressed on basolateral surface of thyroid follicular cell that allows transport of one iodide ion and two sodium ions into cell. Significant intracellular iodide accumulation allows noninvasive imaging with radionuclide techniques and potential for targeted radiation therapy. N = nucleoprotein gene; P/C/V = phosphoprotein, C, and V genes; M = matrix protein gene; F = fusion protein gene; H = hemagglutinin gene; L = polymerase gene; Na⁺ = sodium ion; I⁻ = iodide ion.