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Cure for the cold stymied by variety of virus strains

Hunting for the elusive cure for the common cold, scientists have decoded the genomes of all known strains of the human rhinovirus, the main cause of the malady that makes millions miserable each year.

But don’t toss out the chicken soup yet. There is so much diversity among the strains that hopes for a vaccine or a treatment that would prevent or cure every cold are slim, according to the study, published online Thursday in the journal Science.

The 138 samples – collected from human noses around the world – offer new insight into how the viruses are constructed and how they have evolved, scientists said. They eventually might lead to better drugs for fighting it.

A key finding from the study is that rhinoviruses can swap genetic material among themselves. That means two cold strains infecting the same person might recombine to form a new strain with new properties, complicating the quest for a medicine or vaccine that would remain effective.

But researchers also found that some of the strains were closely matched in certain regions of the genome. These regions could make good targets for therapies, the authors said.

“We may have to have four or five drugs, and you’d need a test at your doctor’s office to know which drug will work,” said Dr. Stephen B. Liggett, director of cardiopulmonary genomics at the University of Maryland School of Medicine and the study’s senior author.

Rhinoviruses – “rhinos” is Greek for “nose” – cause about half of all colds. (Other culprits include coronaviruses, respiratory syncytial viruses and adenoviruses.) Viruses survive by hijacking other cells to serve as hosts, and, in the case of rhinoviruses, the cells they invade line the nose.

Liggett said he became involved in the rhinovirus genome project out of frustration over a lack of progress in treating asthma, his main focus of research. Rhinoviruses exacerbate asthma attacks and in very young children can even program the immune system to develop the disorder, he said.

“From a medical standpoint, a suffering standpoint and a cost standpoint, it touches all the bases as something we should take care of,” Liggett said. “But it gets short-shrifted.”

Over the next three years, the researchers plan to sequence another 1,000 rhinovirus genomes to determine which strains aggravate asthma and cause other serious infections.

Those, and not the strains that cause mere head colds, are likely to be candidates for treatment.

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