A virus can cause illness and even death if you become infected with the wrong one. However, a virus has no malicious intentions; it’s simply a bundle of genetic code programmed to make copies of itself. Researchers have been exploring ways to hijack the functionality of a virus to deliver new beneficial genes to cells. A team from the University of Basel and the University of Geneva has used this approach to create a virus that puts the immune system into cancer-fighting overdrive.
Most attempts to fight cancer with the body’s natural defenses are based on “disinhibiting” your immune system. However, stimulating the immune system to specifically fight the cancer is much more challenging. That’s what the Swiss team is trying to do, though. They created an artificial version of lymphocytic choriomeningitis virus (LCMV, see above), which is known to stimulate a type of immune cell called a cytotoxic T cell or “killer T cell.” They also added a dash of cancer to the recipe, which is not as crazy as it sounds.
In your body right now, there are probably cells that would be described as pre-cancerous. Your killer T cells patrol the body, looking for cells that express certain markers that indicate they may be damaged, infected with a virus, or potentially cancerous. When that happens, the cytotoxic T cell links up with the cell and sends a signal that causes it to self-destruct, which is known as apoptosis. This is fine for the occasional abnormal cell. But there aren’t enough cytotoxic T cells to deal with an aggressive tumor, at least not without some outside intervention like the virus developed by the Swiss team.
The LCMV designed for this study can infect both humans and rodents (which were used for the study), but the infection is self-limiting and not dangerous to the host organism. In addition the LCMV’s natural ability to stimulate cytotoxic T cell production, the team introduced genes found only in cancers. When a virus infects a cell, it uses the internal machinery to process its own genetic code. In this case, the infected cells are making viruses and proteins from cancer cells.
So, the infected cells increase killer T cell activity, and at the same time express cancer cell proteins. This is what helps the immune system recognize and target the cancer. The result in the study was an army of immune cells gunning for both the tumor and the modified virus.
The study shows promising data in a rodent model, but the same can be said of many attempts to battle cancer over the years. More research and analysis will be need to determine efficacy in humans, as well as any potential side effects.