A virus that causes liver diseases in people may have infected birds that shared the planet with dinosaurs.
More than 82 million years ago, a hepatitis B virus infected an ancient bird and got stuck in its genome, a molecular version of a tar pit, researchers report April 30 in Nature Communications. Using fragments of DNA found in modern-day zebra finches, evolutionary biologist Alexander Suh and colleagues at the University of Münster in Germany pieced together a complete genome of the ancient virus. Their analysis suggests that hepatitis B is some 63 million years older than previously thought and that it probably originated in birds and jumped into mammals later.
The discovery is the latest find for paleovirologists, scientists who dig into the DNA of living organisms to find viruses that, at some point in the past, inserted themselves into their host’s genome and stayed there, essentially providing a genetic fossil record. Hepatitis B doesn’t normally insert itself into the genome of an infected person or animal. But in 2010, Cedric Feschotte of the University of Utah found traces of hepatitis B lurking in the zebra finch genome. Using viral DNA fragments, Feschotte calculated the virus’s age as about 20 million years old.