Researchers at Columbia Engineering have developed a new way to treat cancer by making bacteria and viruses work together. They created a system called CAPPSID, which stands for coordinated activity of prokaryote and picornavirus for safe intracellular delivery. Prokaryotes are simple single-celled organisms like bacteria, and picornaviruses are a family of small viruses that can infect cells. In this approach, bacteria that naturally seek out tumors hide a virus inside them, sneak past the body's immune system and release the virus directly into cancer cells to kill them.
The virus used is an oncolytic virus, meaning it targets and destroys cancer cells while sparing healthy ones. The researchers tested this in mice and published the results in Nature Biomedical Engineering. The system aims to improve bacterial cancer therapy, where bacteria attack tumors, by adding a virus for better effect, all while keeping it safe.
Sneaking past defenses and targeting tumors
A major issue with oncolytic virus therapy is that the immune system can destroy the virus before it reaches the tumor, especially if the person has antibodies (proteins that fight specific threats) from past exposures. To fix this, the researchers use Salmonella typhimurium bacteria, which naturally move to low-oxygen tumor areas rich in nutrients. These bacteria act like a Trojan horse, invading cancer cells and then bursting open, or lysing, to release the virus's genetic material, called RNA, inside.
The virus then spreads among cancer cells. To prevent it from infecting healthy tissue, the researchers added a safeguard: the virus needs a protease, a molecule that cuts proteins, provided only by the bacteria. Since bacteria stay in the tumor, the virus can't mature elsewhere.
This marks the first engineered cooperation between bacteria and viruses for cancer treatment. The researchers have filed a patent and are testing it on more cancer types, using various viruses and bacteria strains safe for clinical trials. They hope to build a toolkit for therapies that sense cell conditions, paving the way for clinical use in humans.