MADISON, Wis. A study of the full genetic code of a common human virus offers a dramatic confirmation of the "out-of-Africa" pattern of human migration, which had previously been documented by anthropologists and studies of the human genome.
The virus under study, herpes simplex virus type 1 (HSV-1), usually causes nothing more severe than cold sores around the mouth, says Curtis Brandt, a professor of medical microbiology and ophthalmology at the University of Wisconsin-Madison. Brandt is senior author of the study, now online in the journal PLOS ONE.
When Brandt and co-authors Aaron Kolb and Ccile An compared 31 strains of HSV-1 collected in North America, Europe, Africa and Asia, "the result was fairly stunning," says Brandt.
"The viral strains sort exactly as you would predict based on sequencing of human genomes. We found that all of the African isolates cluster together, all the virus from the Far East, Korea, Japan, China clustered together, all the viruses in Europe and America, with one exception, clustered together," he says.
"What we found follows exactly what the anthropologists have told us, and the molecular geneticists who have analyzed the human genome have told us, about where humans originated and how they spread across the planet."
Geneticists explore how organisms are related by studying changes in the sequence of bases, or "letters" on their genes. From knowledge of how quickly a particular genome changes, they can construct a "family tree" that shows when particular variants had their last common ancestor.
Studies of human genomes have shown that our ancestors emerged from Africa roughly 150,000 to 200,000 years ago, and then spread eastward toward Asia, and westward toward Europe.
Scientists have previously studied herpes simplex virus type 1 by looking at a single gene, or a small cluster of genes, but Brandt notes that this approach can be misleading. "Scientis
|Contact: Curtis Brandt|
University of Wisconsin-Madison