Researchers developed an improved version of a plant virus particle called potato virus X (PVX) by coating it with polyethylene glycol (PEG) to use as a cancer treatment. When injected directly into tumors, these PVX-PEG particles stimulate the body’s immune system to attack cancer cells. The PEG coating makes the treatment more stable, longer-lasting in tumors, and less likely to be rejected by antibodies from prior exposure to plant viruses, while maintaining its cancer-fighting effectiveness.