Reuters
In women, immune cells known as NK, or natural killer, cells have an extra copy of gene called UTX that boosts their virus-fighting capabilities. "While it is well-known that males have more NK cells compared to females, we did not understand why the increased number of NK cells was not more protective during viral infections," study coauthor Dr. Maureen Su, of the David Geffen School of Medicine at UCLA, said in a statement. "It turns out that females have more UTX in their NK cells than do males, which allows them to fight viral infections more efficiently."