An experimental treatment made from a plant virus is effective at protecting against a broad range of metastatic cancers in mice, shows a new study. The treatment, composed of nanoparticles fashioned from the cowpea mosaic virus — a virus that infects black-eyed pea plants — showed remarkable success in improving survival rates and suppressing the growth of metastatic tumors across various cancer models, including colon, ovarian, melanoma and breast cancer.