By deleting certain viral genes, scientists can make viruses that can replicate effectively in tumor cells but not in normal cells. Tumor-selective viral replication can cause tumor cells to lyse, or burst open (oncolysis). The virus can also be modified to produce human signaling proteins that summon immune cells to the site of the lysed tumors, where they encounter tumor antigens. The aim is to generate a broad immunotherapeutic response that can help cytotoxic T cells to recognize and attack distant tumor metastases in the body.
Viruses can be harnessed as vectors for oncolytic immunotherapy. The virus can be modified by inserting, deleting, and/or inactivating various genes in order to achieve desired effects, including:
- A virus that will replicate selectively in tumor cells but not healthy cells.
- The ability to lyse, or burst, tumor cells to expose tumor antigens to the immune system.
- A virus that can produce human signally proteins to summon immune cells to the site of the tumor and teach them to recognize and target tumors with similar antigen profiles.