Tiniest Catch: UA Scientists' Fishing Expedition Reveals Viral Diversity in the Sea

Li Deng, co-first author on the Nature paper, stands on the deck of the research vessel. (Photo: Sullivan lab)
Li Deng, co-first author on the Nature paper, stands on the deck of the research vessel. (Photo: Sullivan lab)

A fishing expedition of microscopic proportions led by University of Arizona ecologists revealed that the lines between virus types in nature are less blurred than previously thought.

Using lab-cultured bacteria as "bait," a team of scientists led by Matthew Sullivan has sequenced complete and partial genomes of about 10 million viruses from an ocean water sample in a single experiment.

The study, published online Monday by the journal Nature, revealed that the genomes of viruses in natural ecosystems fall into more distinct categories than previously thought. This enables scientists to recognize actual populations of viruses in nature for the first time.

"You could count the number of viruses from a soil or water sample in a microscope, but you would have no idea what hosts they infect or what their genomes were like," said Sullivan, an associate professor in the UA's Department of Ecology and Evolutionary Biology, an assistant professor in the Department of Soil, Water and Environmental Science in the College of Agriculture and Life Sciences and member of the UA's BIO5 Institute. "Our new approach for the first time links those same viruses to their host cells. In doing so, we gain access to viral genomes in a way that opens up a window into the roles these viruses play in nature."

Sullivan's team developed a new approach called viral tagging, which uses cultivated bacterial hosts as "bait" to fish for viruses that infect that host. The scientists then isolate the DNA of those viruses and decipher their sequence.

"Instead of a continuum, we found at least 17 distinct types of viruses in a single sample of Pacific Ocean seawater, including several that are new to science – all associated with the single 'bait' host used in the experiment," Sullivan said.

The research lays the groundwork for a genome-based system of identifying virus populations, which is fundamental for studying the ecology and evolution of viruses in nature.

Read the rest of this July 14, 2014 UANews article at the link below.

Date released: 
Jul 29 2014