Pitt biologists find 'surprising' number of unknown viruses in sewage

October 05, 2011

Though viruses are the most abundant life form on Earth, our knowledge of the viral universe is limited to a tiny fraction of the viruses that likely exist. In a paper published this week in the online journal mBio, researchers from the University of Pittsburgh, Washington University in St. Louis, and the University of Barcelona found that raw sewage is home to thousands of novel, undiscovered viruses, some of which could relate to human health.

There are roughly 1.8 million species of organisms on our planet, and each one is host to untold numbers of unique viruses, but only about 3,000 have been identified to date. To explore this diversity and to better characterize the unknown viruses, Professor James Pipas, Distinguished Professor of Biological Sciences Roger Hendrix, and Assistant Professor Michael Grabe, all of the Department of Biological Sciences in Pitt's Kenneth P. Dietrich School of Arts and Sciences, are developing new techniques to look for novel viruses in unique places around the world.

With coauthors David Wang and Guoyan Zhao of Washington University in St. Louis and Rosina Girones of the University of Barcelona, the team searched for the genetic signatures of viruses present in raw sewage from North America, Europe, and Africa.

In the paper, titled "Raw Sewage Harbors Diverse Viral Populations," the researchers report detecting signatures from 234 known viruses that represent 26 different families of viruses. This makes raw sewage home to the most diverse array of viruses yet found.

"What was surprising was that the vast majority of viruses we found were viruses that had not been detected or described before," says Hendrix.

The viruses that were already known included human pathogens like Human papillomavirus and norovirus, which causes diarrhea. Also present were several viruses belonging to those familiar denizens of sewers everywhere: rodents and cockroaches. Bacteria are also present in sewage, so it was not surprising that the viruses that prey on bacteria dominated the known genetic signatures. Finally, a large number of the known viruses found in raw sewage came from plants, probably owing to the fact that humans eat plants, and plant viruses outnumber other types of viruses in human stool.

This study was also the first attempt to look at all the viruses in the population. Other studies have focused on bacteria, or certain types of viruses. The researchers also developed new computational tools to analyze this data. This approach, called metagenomics, had been done before, but not with raw sewage.

The main application of this new technology, says Hendrix, will be to discover new viruses and to study gene exchange among viruses. "The big question we're interested in is, 'Where do emerging viruses come from?'" he says. The team's hypothesis is that new viruses emerge, in large part, through gene exchange. But before research on gene exchange can begin in earnest, large numbers of viruses must be studied, the researchers say.

"First you have to see the forest before you can pick out a particular tree to work on," says Pipas. "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."
-end-


University of Pittsburgh

Related Viruses Articles from Brightsurf:

Sorting out viruses with machine learning
Researchers at Osaka University created a machine-learning system to identify single viral particles that cause respiratory diseases, including coronavirus, using silicon nanopores.

The rafts used by viruses
The study may suggest new strategies to limit virus attacks and prevent or combat diseases like Sars and Covid-19 based on biomedical and engineering principles.

Animals keep viruses in the sea in balance
A variety of sea animals can take up virus particles while filtering seawater for oxygen and food.

Hundreds of novel viruses discovered in insects
New viruses which cause diseases often come from animals. Well-known examples of this are the Zika virus transmitted by mosquitoes, bird flu viruses, as well as the MERS virus which is associated with camels.

First video of viruses assembling
For the first time, researchers have captured images of the formation of individual viruses, offering a real-time view into the kinetics of viral assembly.

Plant viruses may be reshaping our world
A new review article appearing in the journal Nature Reviews Microbiology highlights the evolution and ecology of plant viruses.

Checkmate for hepatitis B viruses in the liver
Researchers at Helmholtz Zentrum M√ľnchen and the Technical University of Munich, working in collaboration with researchers at the University Medical Center Hamburg-Eppendorf and the University Hospital Heidelberg, have for the first time succeeded in conquering a chronic infection with the hepatitis B virus in a mouse model.

How viruses outsmart their host cells
Viruses depend on host cells for replication, but how does a virus induce its host to transcribe its own genetic information alongside that of the virus, thus producing daughter viruses?

Mobile, instant diagnosis of viruses
In a first for plant virology, a team from CIRAD recently used nanopore technology to sequence the entire genomes of two yam RNA viruses.

How ancient viruses got cannabis high
THC and CBD, bioactive substances produced by cannabis and sought by medical patients and recreational users, sprung to life thanks to ancient colonization of the plant's genome by viruses, U of T researchers have found.

Read More: Viruses News and Viruses Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.