From MSNBC:
Researchers have deciphered the structure of a harpoonlike protein some viruses use to enter cells and begin infection. The protein is known as fusion (F) protein and is found on the outer surface of parainfluenza virus 5, a so-called “enveloped” virus that fuses its membrane with the membrane of its host cell before infection. Once the membranes are fused, the virus dumps its genetic content into the healthy human cell’s interior, hijacking the cell’s replication machinery to clone itself. The research, led by Hsien-Sheng Yin of Northwestern University, is detailed in Thursday’s issue of the journal Nature.
More here.