A single injection of a cancer-fighting bug called myxoma virus killed malignant human brain tumors in mice and prolonged the animals’ lives, according to a Canadian study in the journal Cancer Research."We’re extremely encouraged by these results and the apparent cure seen in the mice treated with the active virus compared to untreated mice or those injected with inactivated virus,” study co-author Grant McFadden, a scientist at Robarts Research Institute in Ontario, said in a prepared statement.More than 130 days after the virus was injected into their tumors, more than 92 percent of the 13 mice were alive and apparently “cured,” the study said.