Montana State University

MSU scientists publish findings on competition between viruses, see possibilities for new treatments

February 16, 2016 -- By Amanda Eggert for the MSU News Service

MSU professor Matt Taylor, left, and his team including Theresa Thornburg, Irina Kochetkova, Max DePartee, Alix Herr and Gabby Law (not pictured) recently published findings of their research on viruses in the Journal of Virology. MSU photo by Kelly Gorham.

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A Montana State University researcher and his colleagues have discovered several previously unknown pieces in the puzzle of how viruses spread using a model based on the common Herpes Simplex virus that causes cold sores.

Matt Taylor, MSU assistant professor of microbiology and immunology in the College of Letters and Science and College of Agriculture, and his colleagues published the findings of their research recently in the Journal of Virology. The journal’s editors also selected the paper for the publication’s spotlight section, which highlights research articles of significant interest.

“Viruses must hijack healthy cells for resources needed to reproduce themselves, growing to great numbers. But each cell that a virus attacks has a finite amount of material that can be used to create more viruses,” Taylor said.

This creates competition among viruses themselves as each virus wants to hoard the resources of the cells it has infected. As such, many viruses have developed ways to defend the resources in a cell from other competing viruses, Taylor said.

“We call this phenomenon superinfection exclusion, and we’ve learned some interesting things about how and when this happens,” Taylor said.  

Previously, scientists thought this process of superinfection exclusion was dependent upon the expression of a viral protein called glycoprotein D. Taylor has found that superinfection exclusion can occur independent of this protein, and in a much shorter timeframe than was previously thought.

To make this determination, Taylor and his lab assistants introduced two viruses – Herpes Simplex and a virus known as Psuedorabies – into host cells and timed how long it took for one to establish dominance. Before introducing the viruses into host cells, they created DNA constructs so they would express a blue or yellow fluorescent protein once they infected the host cell. This allowed researchers to determine which virus established dominance and how long it took.

They found that within two hours, the faster virus excluded the other from the host cell and its resources.

Taylor theorizes that superinfection exclusion also provides a fitness advantage, allowing only the best viruses to replicate to high amounts and spread between people.

The precise mechanism driving this process is still uncertain, but Taylor has already started a new round of experiments.

“We now have a very short list of about five viral genes that have the potential to be mediating this process,” Taylor said.

Taylor said his findings have implications for scientists’ understanding of viral transmission and therapies for cold sores and other viral infections.

“It is possible superinfection exclusion could be activated before the first virus infects the cell,” he said. “Therapies that activate exclusion could be used to prevent herpesvirus infection or cold sore formation.”

Taylor also expressed appreciation for wide-ranging support the researchers received.

“Much of this work wouldn’t have been possible without the research infrastructure provided by the university, the department, the CoBRE-funded Center for Zoonotic and Emerging Infectious Diseases, and the Murdock Cell and Molecular Fluorescence Imaging Facility,” he said.

The research leading to the Journal of Virology paper was initiated during the 2014 Hughes Summer Undergraduate Program, a 10-week program where students conducted lab research and presented their findings under the mentorship of MSU professors.

Like other summer undergraduate research programs offered at MSU, the Hughes Summer Undergraduate Program allowed students new to laboratory research to become immersed in the scientific process by conducting lab research and presenting their findings.

Taylor worked with AnneMarie Criddle, a microbiology major and genetics minor. After completing the summer program, Criddle continued her research through the academic year as a Hughes Scholar.

Taylor, Criddle and three other members of Taylor’s lab started focusing on publication once they amassed enough compelling data to share their findings.

“It’s common to stay involved,” said Martha Sellers, the associate director of Hughes Undergraduate Biology Program. “In AnneMarie’s situation, she didn’t just stay involved, she continued to increase her knowledge, her skills and her capacity to participate. I think all of that led to the opportunity to be published.”

Criddle, the paper’s lead author, has since started a yearlong medical laboratory science program in Spokane, Wash.

“[At MSU] I learned that research takes a lot of perseverance, thought and patience. I take that wherever I go now,” she said. “I have that perspective and respect for people who do research.”

Contact: Matt Taylor, (406) 994-7467 or