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New Research on RNA Silencing

UCR Scientists Discover a Novel Adaptive Antiviral Defense Mechanism in Animals

(May 16, 2002)

Scientists at the University of California, Riverside have bagged the cover of the May 17 issue of Science, one of the world's premier scientific journals, with research about "RNA silencing," a novel adaptive antiviral defense in the animal kingdom. Shou-Wei Ding, assistant professor of plant pathology, discovered that when animal cells are attacked by a virus, the cells use RNA silencing to protect themselves from the virus. The discovery could lead to new gene therapies and vaccine designs.

RNA or ribonucleic acid is similar to a single strand of DNA or deoxyribonucleic acid (two strands of DNA typically make up a cell's chromosome), but with a small chemical difference in the structure of the chemical units called nucleotides. Some viruses use RNA as their chromosomes, but a universal role for RNA is as the messenger RNA (mRNA), to convert the genetic information in DNA into functional proteins.

RNA silencing was first discovered in transgenic plants in 1990 and only recently in animals, where it is also known as 'RNA interference.' RNA silencing regulates gene expression by a specific degradation of its mRNA and, after its initial triggering, the RNA silencing mechanism has 'memory,' knowing which RNA to destroy, by virtue of the sequence of the four building blocks (nucleotides) of RNA.

"In our experiments, we infected fruit fly cells with an RNA virus," said Ding. "This triggered strong silencing of the viral RNAs in the fly cells. We further demonstrate that the same virus also directs expression of a protein that suppresses RNA silencing in the fly cells, thus ensuring successful infections."

It is well known that in plants, RNA silencing serves as an antiviral defense. Ding and two postdoctoral researchers working in his laboratory show for the first time that animal cells have used RNA silencing to defend against viral infections. Because the animal viral suppressor identified also blocks RNA silencing in plants, their results provide the first experimental evidence for a highly conserved antiviral pathway in the animal and plant kingdoms.

In addition to having potential applications in gene therapy and vaccine design, the new findings may result in new treatments for recalcitrant human and animal viral diseases being developed based on the RNA silencing adaptive defense, which is distinct to the known adaptive immunity that targets protein antigens of viruses. "For example, blocking the action of viral silencing suppressors should lead to rapid virus elimination by the cell's own antiviral defense," said Ding.

The University of California, Riverside ( is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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