Many lethal viruses are believed to have originated with, or been transmitted through, different species of bats, and that has raised scientific interest in whether or not there's something about the creatures that encourages viruses that are likely to jump species barriers to evolve inside them. One recent study, co-authored by postdoctoral fellow Cara Brook, suggests a possible reason. Some bats have unusual immune systems, with an antiviral process called the interferon pathway that is always active, not just triggered by an infection. Through a series of experiments on bat cells that do and do not have this pathway, as well as on monkey cells that were used as a control, the researchers concluded that always-on interferon pathways likely speed viral evolution, making bats more abundant sources of virulent new viruses than other groups of mammals. For more on this, see our press release at Berkeley News.