A research team formed by researchers from the University of Barcelona (UB), the Bellvitge Biomedical Research Institute (IDIBELL) and the University of Munich has developed a new Vaccinia virus strain that represents a significant breakthrough in viral immunotherapy research and evidences its therapeutic potential to treat cancer patients. This new variant is able to replicate in tumor cells and, at the same time, maintains a high capacity to activate the patient’s immune defenses against tumors. The study, published in the scientific journal Molecular Therapy, has received support from the Spanish Cancer Association and the State Research Agency. The virus has been shown to be effective in mouse models against various types of cancer such as melanoma, colon and kidney cancer. This advance represents a remarkable step forward in the research of viral immunotherapy and offers new hopes in the treatment of cancer.