Newly discovered ocean virus could be present in humans

Researchers have discovered a new virus family that may be critical in killing marine bacteria and maintaining the balance of the underwater environment. There is also evidence to suggest that these types of viruses are present in the human gut.

Study co-author Dr. Libusha Kelly is an assistant professor in Microbiology & Immunology at the Albert Einstein College of Medicine.

“Bacteria are key components at the bottom of the ocean’s food chain, meaning that viruses–which can infect and kill bacteria–are also vital for understanding the ocean’s health and function,” said Dr. Kelly. She pointed out that viruses also kill bacteria in humans.

“By expanding what’s known about the kinds of viruses that infect bacteria, this study allows us to look at other ecosystems like the human gut, to detect previously unknown viruses and to learn how they might be influencing bacterial populations that are vital for health or that contribute to disease,” said Dr. Kelly.

The most abundant viruses on the planet are double-stranded DNA (dsDNA) viruses. The “tailed” variety of dsDNA viruses have been studied in much more detail than the “non-tailed” dsDNA viruses. This is primarily due to the fact that the non-tailed dsDNA are not as easy to culture and analyze.

“Our collaborator Martin Polz at MIT developed a model system that overcomes these limitations, making it possible to study the role of viruses in complex microbial communities in the lab,” explained Dr. Kelly.

The research team collected water samples from off the coast of Massachusetts for three months. All of the viruses detected in the samples were incubated for two weeks in cultures of Vibrionaceae bacteria, which is a common marine bacteria.

By the end of the incubation period, over 200 viruses that had infected the bacteria were selected at random for genome sequencing. A previously unknown family of non-tailed dsDNA viruses were identified from the genetic material of eighteen specimens.

The researchers tested the new family of viruses, which they named Autolykiviridae, in more than 300 strains of Vibrionaceae bacteria. The experimentation revealed that these non-tailed viruses were capable of wiping out many more strains of bacteria than the tailed viruses found in the water samples.

“We showed that viruses related to the Autolykiviridae are infecting many diverse groups of ocean bacteria as well as other bacterial groups that we cannot currently identify,” said Dr. Kelly.

According to the researchers, these viruses most likely exist outside of the ocean as well.

“We’ve found related viral sequences in the gut microbiome, but we don’t yet know how they influence microbial communities in the gut or how important they are for health,” said Dr. Kelly.

The study was published online in the journal Nature.

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By Chrissy Sexton, Earth.com Staff Writer