Viruses from Yellowstone National Park and Elsewhere Travel Far, Independently

Viruses found in the acidic hot springs of Yellowstone National Park might be well adapted to their harsh environments, but they can also travel surprising distances to very different locales, according to new research from the National Science Foundation (NSF).

The Yellowstone viruses live on host microbes in the hot springs, where temperatures and pH levels make the environment similar to boiling battery acid. However, researchers from Montana State University and Idaho National Laboratory found the viruses can travel independently of their hosts, making their way to other hot springs in the area that are miles away. The researchers also found evidence indicating the Yellowstone viruses might be able to make their way to an even more exotic destination: the Sargasso Sea, located near Bermuda.

The discovery is noteworthy because it adds to a growing body of evidence showing viruses can move independently of their host organisms.

"(It's) helping to blow out of the water the concept that viruses always have an intimate relationship with their hosts," said Lita Proctor, a program director with the NSF.

The scientists tracking the Yellowstone viruses spent two years sampling the hot springs' geochemistry, microbe populations and population mixes of two different virus families. They studied three hot springs in the national park, taking new samples every 30 days.

"Because each hot spring acts like a geographically isolated island, we could study how the populations of viruses in these hot springs changed over time," said Mark Young, a member of the research team from Montana State.

What they found was that, while the chemistry and microbial makeup of the hot springs stayed about the same throughout, the virus populations in each spring changed "in a very random way," Young said. After analyzing the DNA sequences of the different viral populations, the researchers concluded the changes were caused by migration between springs rather than by genetic mutations in individual virus populations that stayed put.

The researchers believe the viruses might travel from place to place by hitching a ride on droplets of steam rising from the hot springs. However, they add it's also possible some viruses might have migrated via underground streams.

After reviewing earlier research showing the presence of Yellowstone hot spring viruses on microbial hosts in the Sargasso Sea, the researchers concluded those viruses were also likely to have traveled there independently, becoming temporary rather than reproducing residents. That's because, as of now, the Yellowstone viruses are known to replicate only in microbes that live in the extreme conditions of the hot springs.

New insights into how viruses travel are important for understanding evolution and ecology. Viruses are the most common biological entity on Earth as well as the planet's largest storehouse of genetic material, and only one one-thousandth to one-tenth of a percent of all viruses have yet been identified.

"There is a huge pool of viruses out there that can move in and out of an environment," Young said.

National Science Foundation, "Mobile Microbes: Viruses Living in Yellowstone's Hot Springs Travel Near and Far." URL: (http://nsf.gov/news/news_summ.jsp?cntn_id=110663)