Cell barrier shows why bird flu not so easily spread among humans

Writing in the journal Nature, a team of scientists led by UW-Madison virologist Yoshihiro Kawaoka reports differences in the receptors on cells in the lower and upper parts of the human respiratory system that avian flu viruses use to gain access to cells. The work shows why the avian influenza virus does not yet transmit easily from human to human. Illustration: Jeff Jerred /University of Wisconsin