Fig. 5

Viral oncolytic treatment in CSCs. Viruses can be delivered to the tumor site through direct injection or systemic administration. Viral alterations, such as virulence gene deletion or nonhuman host range, render normal cells non-permissive to viral infection. However, it has been observed that CSCs may be susceptible to viral infection. To facilitate viral entry, surface antigens specific to CSCs may be selected. During the progression of viral replication, foreign gene products such as cytokines (e.g., IL-12), enzymes (e.g., chondroitin), and other proteins (e.g., angiostatin) are synthesized. The release of foreign products following host-cell lysis may activate an immune response towards cancer stem cell (CSC) antigens by cytokines, leading to the activation of T cells, NK cells, and macrophages (MΦ) in uninfected cells. Enzymes or inhibitory proteins have the potential to disrupt the microenvironment of the CSC. Viruses can propagate to adjacent tumor cells [81]