Scientists are making progress in understanding the rhinovirus – the virus most often responsible for common colds and other upper respiratory tract infections.
Dr Stephen Liggett of the University of Maryland, Baltimore, USA, and colleagues have constructed a "family tree" of rhinovirus strains. This will help drug manufacturers develop an effective treatment or vaccine by highlighting which strains to target, the experts believe.
They say that 99 strains of rhinovirus have been identified to date. Efforts to find a drug treatment have generally failed because they worked on people infected with certain strains, but not others.
The researchers aimed to clearly outline the different strains by completing the genome sequences for all known rhinoviruses, plus some new strains. Findings are published in the February 13 issue of Science. The rhinovirus family tree was created by comparing the genome sequences and physical features of each virus, to find which were the most similar.
The authors say they identified new branches on the tree, in addition to the two known major groups known as HRV-A and HRV-B. Findings demonstrate that "distantly-related viruses can recombine and produce new strains", they explain.
The research also suggests that one specific piece of the rhinovirus genome sequence is particularly variable and "may influence the microbe’s virulence", because the corresponding sequence in the poliovirus is known to play this role.
"These findings should lay the groundwork for researchers to investigate rhinovirus evolution, diversity and drug-resistance," the authors conclude.
Developing effective treatments for human rhinovirus infection is crucial, they add, as it can exacerbate pre-existing illnesses and lead to serious complications.
Palmenberg, A.C. et al. Sequencing and Analyses of All Known Human Rhinovirus Genomes Reveals Structure and Evolution. Science, February 13, 2009.
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