Cures for the common cold could be a step closer to reality with the development of a virus "family tree", it has been claimed.
A study from the University of Maryland Medical Centre in the USA managed to link up all known strains of the human rhinovirus, which causes the common cold, by piecing together elements of their genetic code.
The research, published in the journal Science, found that the viruses are organised into about 15 distinct groups descended from distant ancestors and may explain why previous attempts to develop a single treatment for all the strains have failed to work.
By studying the viral genealogy, scientists say they may be able to discover weak spots that could be targeted with specific treatments.
Study leader, Professor Stephen Liggett, said: "There has been no success in developing effective drugs to cure the common cold, which we believe is due to incomplete information about the genetic composition of all these strains.
"We generally think of colds as a nuisance, but they can be debilitating in the very young and in older individuals, and can trigger asthma attacks at any age."