Around half of all babies develop a respiratory syncytial virus infection within the first year of life, and almost all have had at least one infection with the virus by the age of three; most children recover from the infection within about a week, but 3–10% of these infants develop severe bronchitis and require hospital treatment. Researchers at the University of Texas Southwestern Medical Center in Dallas wanted to discover whether respiratory syncytial virus persists in the lungs after infection.

To do this they infected mice with a live virus or a heat-inactivated version of the virus then monitored them for 42 days, checking their respiratory function at set intervals. At the end of the 42 days they found evidence of the virus in every mouse infected with live version, but not in any mouse infected with the heat-inactivated virus. Mice infected with the live virus also showed significantly greater levels of airway inflammation, had poorer lung function and wheezed more often than the other mice. Furthermore, the amount of virus detected in the lungs of the mice directly related to the severity of airway ‘hyper-reactivity – the main airway-narrowing characteristic of asthma attacks in humans.

The researchers suggest that a potential new mechanism for asthma related to viral infections in children that could be associated with respiratory syncytial virus.

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More research on the infant allergy/intolerance

First Published in December 2008

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