GALVESTON, Texas -- The most common cause of infant hospitalization in the United States, respiratory syncytial virus, infects virtually all children by age two. Along with the influenza virus, RSV is a major contributor to the approximately two million infant deaths worldwide caused every year by respiratory infections, according to the World Health Organization. Worse yet, theres no safe and effective RSV vaccine available to prevent severe respiratory infections, and no specific antiviral therapy to treat them.
Normally RSV results only in a cold-like upper respiratory infection. But in some babies, it spreads deep into the lungs, where it prompts coughing, wheezing and extreme difficulty in breathing, a clinical syndrome known as bronchiolitis. In these cases, the childs survival may require immediate medical attention.
For the past four decades, medical science thought it knew how this dangerous condition arose from such a common virus. Scientists blamed an overreaction in the lungs by specific immune-system cells, T lymphocytes (also known as "T cells"), for the most severe symptoms of infection.
But now, researchers at the University of Texas Medical Branch at Galveston (UTMB), the State University of New York at Buffalo, the University of Chile, the Hospital Roberto del Rio in Santiago, Chile, the University of Texas Southwestern Medical Center, Dallas, and MedImmune Inc. of Gaithersburg, Md., have turned that dogma on its head.
Instead of being caused by too strong an immune response, theyve shown that severe RSV infections in the lower respiratory tract actually are associated with an inadequate immune reaction a characteristic they share with fatal influenza infections, which were also studied by the group. Their findings have major implications for efforts to develop therapies for RSV and perhaps other viral respiratory infections during infancy.