Trick that aids viral infection is identified

January 30, 2014

Scientists have identified a way some viruses protect themselves from the immune system's efforts to stop infections, a finding that may make new approaches to treating viral infections possible.

Viruses have well-known strategies for slipping past the immune system. These include faking or stealing a molecular identification badge that prevents a cell from recognizing a virus.

Scientists at Washington University School of Medicine in St. Louis and elsewhere have found some viruses have another trick. They can block the protein that checks for the identification badge.

The blocking structure is called a stem-loop, found at the beginning of the virus's . This is the first time scientists have found an immune-fighting mechanism built directly into the genetic material of a virus. They are looking for ways to disable it and searching for similar mechanisms that may be built into the genetic material of other disease-causing microorganisms.

"When the stem-loop is in place and stable, it blocks a host cell immune protein that otherwise would bind to the virus and stop the infectious process," said senior author Michael Diamond, MD, PhD, professor of medicine. "We found that changing a single letter of the virus's genetic code can disable the stem-loop's protective effects and allow the virus to be recognized by the host immune protein. We hope to find ways to weaken the stem-loop structure with drugs or other treatments, restoring the natural virus-fighting capabilities of the cell and stopping or slowing some ."

Most life forms encode their genes in DNA. To use the instructions contained in DNA, though, cells have to translate them into a related genetic material, RNA, that can be read by a cell's protein-making machinery.

Some viruses encode their genes directly in RNA. Examples include West Nile virus and influenza virus, and the viruses that cause sudden acute respiratory syndrome (SARS), yellow fever and polio.

When a virus infects a cell, it co-opts the cell's protein-making machinery to make viral proteins. These proteins allow the virus to replicate. Copies of the break into other cells, repeat the process, and the infection spreads.

The researchers studied alphaviruses, a group of RNA viruses that cause fever, encephalitis and infectious arthritis. They showed that a single-letter change in the RNA of an alphavirus strengthened the stem-loop. When the structure was stable, a key called Ifit1 was blocked from binding to the viral RNA and the infection continued unchecked. But when the stem-loop was unstable, Ifit1 would bind to the viral RNA and disable it, stopping the infectious process.

"Knowing about this built-in viral defense mechanism gives us a new opportunity to improve treatment of infection," Diamond said. "To control emergent infections, we must continue to look for ways that have antagonized our natural defense mechanisms and discover how to disable them."

Explore further: Some brain cells are better virus fighters

More information: Hyde JL, Gardner CL, Kimura T, White JP, Liu G, Trobaugh DW, Huang C, Tonelli M, Paessler S, Takeda K, Klimstra WB, Amarasinghe GK, Diamond MS. A viral RNA structural element alters host recognition of non-self RNA. Science Express, Jan. 31, 2014.

Related Stories

Some brain cells are better virus fighters

March 7, 2013

(Medical Xpress)—Viruses often spread through the brain in patchwork patterns, infecting some cells but missing others. New research at Washington University School of Medicine in St. Louis helps explain why. The scientists ...

New findings reveal protein structure in rubella virus

December 10, 2013

(Medical Xpress)—Researchers have determined the structure of the rubella virus capsid protein, which is central to the virus's ability to assemble into an infectious particle and to infect humans.

Researchers find new rhinovirus infection insights

December 31, 2013

(Medical Xpress)—On average, each of us catches a cold two to three times a year. However, how the common cold virus actually infects us is only partly understood. Researchers from the Max F. Perutz Laboratories of the ...

Recommended for you

Researchers grow retinal nerve cells in the lab

November 30, 2015

Johns Hopkins researchers have developed a method to efficiently turn human stem cells into retinal ganglion cells, the type of nerve cells located within the retina that transmit visual signals from the eye to the brain. ...

Shining light on microbial growth and death inside our guts

November 30, 2015

For the first time, scientists can accurately measure population growth rates of the microbes that live inside mammalian gastrointestinal tracts, according to a new method reported in Nature Communications by a team at the ...

Functional human liver cells grown in the lab

November 26, 2015

In new research appearing in the prestigious journal Nature Biotechnology, an international research team led by The Hebrew University of Jerusalem describes a new technique for growing human hepatocytes in the laboratory. ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.