Many of these viral agents may be detrimental to humans

Oct 6, 2011 09:44 GMT  ·  By
Thousands of previously-unknown viruses were detected in sewage from Europe, Africa and North America
   Thousands of previously-unknown viruses were detected in sewage from Europe, Africa and North America

Sewers are apparently a fertile breeding ground for viruses. In a new investigation, an international team of scientists managed to discover thousands of previously-unknown microorganisms, of which many could have negative impacts on human health.

The work was carried out by experts with the Washington University in St. Louis (WUSL), the University of Pittsburgh and the University of Barcelona, in Spain. Details of the study were published in this week's online issue of the journal mBio.

Determining the exact number of viruses that infect all living species – plants, animals and other microorganisms alike – is impossible. Thus far, science has only been able to identify and catalog about 3,000 viral agents, but countless more remain to be discovered.

This exquisite level of biodiversity ensures that genetic material can be shuffled around, spawning new breeds of viruses over very short time frames. The research team wanted to discover more types of such pathogens, by looking in unique places where such investigations are not usually led.

James Pipas, Distinguished professor of biological sciences Roger Hendrix, and assistant professor Michael Grabe lead the team of scientists that carried out the effort. All of them are based at the Pitt School of Arts and Sciences Department of Biological Sciences (DBS).

WUSL experts David Wang and Guoyan Zhao were the coauthors on the new study, as was University of Barcelona scientist Rosina Firones. Together, the investigators analyzed raw sewage collected from Africa, Europe and North America.

Genetic analysis revealed the presence of 234 known viruses from 26 different families. “What was surprising was that the vast majority of viruses we found were viruses that had not been detected or described before,” Hendrix explains.

Viral agents that preyed on bacteria were the most common, since sewage is known to contain vast colonies of bacteria that feed on organic matter. Massive numbers of planet viruses were also discovered, which did not really surprise scientists.

“First you have to see the forest before you can pick out a particular tree to work on. If gene exchange is occurring among viruses, then we want to know where those genes are coming from, and if we only know about a small percentage of the viruses that exist, then we’re missing most of the forest,” Pipas explains.

At this point, the team intends to conduct a study on the origins of new viruses. The scientists already have some theories about this aspect, but they don't yet have sufficient data to confirm or infirm either of them.