Viral Infections in Infancy Linked to Asthma

Researchers have outlined a mechanism at the cellular level that may explain how severe respiratory infections in infancy are linked to the later development of asthma.

Investigators from the Washington University School of Medicine (St. Louis, MO, USA) created a mouse model by injecting a population of mice selected for asthma susceptibility with sendai virus. Active virus infection triggered the sorts of changes in the cellular mucosa that line airway passages that are typical for asthma. However, after viral clearance they found that the mice no longer developed mucous cell metaplasia, the change from one type of cell to another generally caused by some sort of abnormal stimulus.

Results published in the October 29, 2007, issue of the Journal of Experimental Medicine also revealed that during the active phase of the infection, the mice produced antibodies and immune signals similar to those produced during an allergic response, instead of those typically made in response to infection.

"A severe respiratory infection in infancy greatly increases the risk of developing asthma,” said first author Dr. Mitchell Grayson, assistant professor of medicine at Washington University School of Medicine. "We think genetically predisposed individuals will tend to have this kind of immune reaction to a severe respiratory viral infection. In those people, an allergic-type response could be part of their antiviral immune response. That sets them up to make antibodies against a lot of environmental substances, like pet dander or pollen, and they can go on to develop allergies or asthma. It may be possible to prevent many cases of asthma and other chronic inflammatory airway diseases by stopping allergic-type antibody production after a severe viral infection in infants.”


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Washington University School of Medicine