By AMY DOCKSER MARCUS, APRIL 12, 2011, wsj.com:
The human genome is littered with the genetic remains of ancient viruses that once infected people but now lie dormant. Until recently, scientists didn't believe they played a role in modern disease.
New research is causing many scientists to think again. Recent studies suggest these old virus shards may play a role in Hodgkin's lymphoma, multiple sclerosis, rheumatoid arthritis and other diseases.
The ancient viruses scientists are most interested in date from waves of infections that took place as recently as 100,000 to 200,000 years ago. In modern humans, the genes were most likely inherited from a common ancestor infected with retroviruses, probably from rodents.
Unlike other kinds of viruses, retroviruses copy their own genes into a host's DNA. Some of the retroviruses are believed to have infected sperm cells and eggs, ensuring the virus would be passed from generation to generation in the genome. Read more>>