WASHINGTON -- The viruses that cause measles, AIDS, Ebola and influenza may all be distantly related, perhaps descended from a common ancestor, researchers reported Friday.
Scientists who have imaged the viruses say they all use a very similar mechanism to enter the cells they infect."The structure of this molecule shows that a widely dissimilar virus, a virus that everybody thought was very different from the other group, ends up in fact having remarkable similarities," virologist Robert Lamb, a member of the team at the Howard Hughes Medical Institute at Northwestern University in Chicago that did the work, said in a statement.
"It suggests a common ancestor among all these viruses, where one would have thought them not to be related at all."
Writing in the journal Molecular Cell, the researchers said they used X-ray crystallography to look at the "fusion protein" of a paramyxovirus. The paramyxoviruses cause diseases such as measles, mumps, croup and viral pneumonia.
The fusion protein serves as a grappling hook that snags the infected cell, pulling it together with the virus. The virus can then inject its own genetic material into the cell, forcing it to pump out copy after copy of the virus.
The researchers were surprised to find their fusion proteins so closely resemble those of other viruses, such as HIV and Ebola.
Knowing just how this mechanism works can help scientists design defenses against it, crystallographer Theodore Jardetzky said.
"The fusion protein was of particular interest, because for HIV it's been shown that if you can inhibit the fusion protein, you can block viral entry," Jardetzky said.
An experimental new class of HIV drugs targets this protein.