The Viral Family Tree

New research suggests viruses that infect hosts in all three domains of life might have originated from a single ancestor.

Above is an electron micrograph image of an adenovirus, one sort that infects humans. Other virus infect other animals, plants and even bacteria. Only in recent years have scientists come to realize that that there are great structural similarities among seemingly unrelated viruses, says Roger Burnett of the Wistar Institute.

Burnett and colleagues previously determined the structure of a virus called PRD1 that infects bacteria. They found that it has remarkable structural similarities to human adenoviruses, which cause various diseases, including respiratory infections.

Now the researchers have created structural models that show similarities in viruses that infect eukarya (animals, plants, and other higher order organisms), bacteria and and archaea, a recently described group of microorganisms that differ from bacteria and are commonly found in extreme environments like geysers, and alkaline, acidic or salty waters.

These structural similarities suggest that the viruses, despite their genomic variations and differences in hosts, may have evolved from a common ancestor billions of years ago, the scientists said. The findings were published in the Dec. 3 issue of Molecular Cell.

-- LiveScience Staff

Photo Credit: CDC