"We've discovered what appears to be a basic mechanism of resistance—to heat, to desiccation, to ultraviolet radiation," says Edward H. Egelman. "And knowing that, then, we can go in many different directions, including developing ways to package DNA for gene therapy." (Credit: Jeffery Simpson/Flickr)

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Acid-loving virus shows how to clad DNA in armor

A virus that can survive in nearly boiling acid may offer a blueprint for cladding DNA in armor-like packaging to battle a variety of diseases.

“What’s interesting and unusual is being able to see how proteins and DNA can be put together in a way that’s absolutely stable under the harshest conditions imaginable,” says Edward H. Egelman of the biochemistry and molecular genetics department at University of Virginia.

“We’ve discovered what appears to be a basic mechanism of resistance—to heat, to desiccation, to ultraviolet radiation. And knowing that, then, we can go in many different directions, including developing ways to package DNA for gene therapy.”

Strange virus

Finding effective packaging for DNA delivery is important because the human body has many ways to degrade and remove foreign DNA; that’s how it combats harmful viruses.

But that protective mechanism becomes a major obstacle for doctors seeking to use genes to battle disease. Creating an impenetrable packaging would overcome that problem. Scientists say this strange virus offers a promising template.

The virus, SIRV2, infects a microscopic organism known as Sulfolobus islandicus that lives in “extremely unusual” conditions: acidic hot springs where temperatures top 175 degrees Fahrenheit.

A new study, published in the journal Science, identifies surprising similarities between the SIRV2 virus and the spores bacteria form to survive in inhospitable environments.

“Some of these spores are responsible for very, very horrific diseases that are hard to treat, like anthrax,” Egeleman says. “So we show in this paper that this virus actually functions in a similar way to some of the proteins present in bacterial spores.”

Spore destruction

Spores are also formed by C. difficile, which now accounts for approximately 30,000 deaths each year in the United States and has been classified by the Centers for Disease Control and Prevention as having a threat level of “urgent.”

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“Understanding how these bacterial spores work gives us potentially new abilities to destroy them,” Egelman says. “Having this basic scientific research leads in many, many directions, most of which are impossible to predict, in terms of what the implications are going to be.”

So how does the virus survive such inhospitable conditions? SIRV2, it turns out, forces its DNA into what is called A-form, a structural state identified by pioneering DNA researcher Rosalind Franklin more than a half-century ago.

“This is, I think, going to highlight once again the contributions she made, because many people have felt that this A-form of DNA is only found in the laboratory under very non-biological conditions, when DNA is dehydrated or dry,” Egelman says. “Instead, it appears to be a general mechanism in biology for protecting DNA.”

Source: University of Virginia

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