CHICAGO (Reuters) – U.S. researchers have discovered antiviral proteins in cells that naturally fight off influenza infections, a finding that may lead to better ways to make vaccines and protect people against the flu. They said a family of genes act as cell sentries that guard cells from an invading influenza virus, the team reported on Thursday in the journal Cell. "This prevents the virus from even getting into the cell," said Stephen Elledge of Harvard Medical School and a Howard Hughes Investigator at Brigham & Women's Hospital. "It is out there fighting the flu all of the time," Elledge...