Cold Viruses Changing Shape, Research Finds

Posted: July 12, 2013 at 5:00 am, Last Updated: July 16, 2013 at 2:15 pm

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By Michele McDonald

Don Seto. Creative Services photo

Don Seto. Creative Services photo

Dubbed the “uncommon cold virus,” highly contagious adenoviruses are doing more than just making people feel miserable — they’re causing severe eye infections. And there’s evidence the viruses are jumping from animals to humans.

Don Seto, a professor of the bioinformatics and computational biology program in the School of Systems Biology at George Mason University, is a well-known expert in the field of adenoviruses. He’s working on predicting the next human adenovirus pathogen and recently helped pinpoint a new eye virus that can cause blindness.

First discovered in 1953, adenoviruses typically are more of a nuisance than a fight for life. They sweep through such close groups as military training camps, schools, youth camps, nursing homes and the like. Respiratory illness, “pink eye” and gastrointestinal distress are the usual hallmarks. A respiratory outbreak last year in China was thought to be SARS, but turned out to be an adenovirus.

Adenoviruses also may cause blindness and even death when they attack the eyes or affect HIV patients and transplant recipients with low immune systems.

Seto spent his sabbatical this spring in the labs at the Massachusetts Eye and Ear Infirmary, associated with Harvard Medical School, to work with colleagues.

He dove into the problem of diagnosing an eye infection that at first appeared as a respiratory bug. It’s a tricky puzzle to unravel viruses that look like one virus but later reveal themselves to be quite another. Diagnosing is the first step to creating drugs to prevent these pathogens.

For example, a child in Canada had what first appeared to be a normal respiratory virus. A closer look at the virus’genome revealed it to be a combination of respiratory microbes and microbes related to pink-eye, and is a potential eye pathogen, Seto says.

That particular type of virus appeared in Japan and Germany some 20 years ago but researchers didn’t have the tools to determine what it was. Again, due to the novel recombination of genomes, it became a potent and highly contagious eye pathogen.

Seto is hard at work changing that situation. He’s remaking how adenoviruses are studied and classified, says James Chodosh, the David G. Cogan Professor of Ophthalmology in the field of Cornea and External Disease at Harvard Medical School and a Seto colleague. In the past, and sometimes still today, researchers look at only a small part of the virus to identify it. That’s simply not enough, Seto says.

“Genomics is a very good way to determine what virus you have exactly and correctly,” he says. To that end, he is chairing a National Institutes of Health-sponsored committee, the Human Adenovirus Working Group, which determines, using genomics and bioinformatics, whether a newly discovered adenovirus is a new type.

Seto, Chodosh and other researchers are sequencing the genes of adenoviruses as part of a project funded by NIH. Studying the gene itself may help researchers figure out what the next virus could be. Sometimes two different adenoviruses combine to make a new one.

Human and non-human, specifically primate, adenoviruses have a lot in common, which can lead to a little too much sharing. For one persistent human adenovirus, for example, the genomic sequence is 98 percent identical to a chimpanzee virus, Seto says.

“These viruses are very similar and can jump from humans to chimps and gorillas very easily, and vice versa,” Seto says.

Seto’s approach puts him at odds with some long-held beliefs. “The field currently believes very strongly that there are human adenoviruses and non-human primate adenoviruses,” he says. “But the data shows otherwise. You can’t just ignore the data.”

Last year, a SARS-like respiratory virus popped up in the Middle East. Researchers now think it may have originated as a bat or camel virus before moving to humans, Seto says. SARS itself is thought to be either a bat or civet virus that jumped into humans, causing a pandemic with a high mortality rate.

As a result, researchers need to look at the “non-human” population for the next wave of viruses, Seto says.

Write to Michele McDonald at mmcdon15@gmu.edu

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